Posts Under Tag: Great Scientists

Heinrich Daniel Ruhmkorff

Heinrich D. Ruhmkorff was a mechanic and electrical researcher who invented the Ruhmkorff’s coil, a type of induction coil that could produce sparks more than 1 foot (30 centimetres) in length. This coil was used in the first radio transmitters and some other primitive electrical and electronic devices.

The electrical researcher Heinrich D. Ruhmkorff was born on January 15, 1803, in Hannover, Germany. After apprenticeship to a German mechanic, Ruhmkorff worked in England with Joseph Brahmah, inventor of the hydraulic press. In 1855 he opened his own shop in Paris, which became widely known for the production of high-quality electrical apparatus. There he built a number of improved induction coils, including one in 1851 that was awarded a 50,000-franc prize in 1858 by Emperor Napoleon III as the most imporant discovery in the application of electricity.

He was able to improve Callan’s two-winding induction spark-coils, on the basis of the research conducted in Paris by Masson and Breguet in 1842, in such a way that since then these devices bear his name. Ruhmkorff’s coil could produce sparks more than 1 foot (30 centimetres) in length. Ruhmkorff’s coils, which produced high-voltage current within a secondary armature winding, were used for the operation of Geissler and Crookes tubes as well as for detonating devices.

Ruhmkorff’s induction coil (ca. 1910)

The first patents date back to 1851 and follow one another introducing a few fundamental novelties. The iron core is still rectilinear and the primary winding, close to the iron, and the secondary winding, are arranged on it. The primary winding is fed by a storage battery, through a switch operated by the magnetized core. The current in the primary winding is pulsed, and the voltage on the secondary is alternating. First of all, Ruhmkorff took particular care of the secondary insulation, using for the winding a lacquered copper wire, then inserting between one layer and the other a sheet of paper or varnished silk and finally separating the primary winding from the secondary one by a glass pipe.

Afterwards, by using an invention of the English E. and C. Bright, he divided the secondary winding into compartments, each one wound and insulated from the others; all were then connected in series. In this way the spots between which the highest difference in potential was to be found were at the greatest possible distance. The secondary wire could reach even tens of kilometers of total length. Later Ruhmkorff improved the mercury switch by covering the mercury with alcohol to extinguish the spark and avoid oxidation. Finally, applying fizeau’s device, he connected a capacitor between the terminals of the primary interruption bow, in order to increase the induced voltage. The frontal pawn is used to invert the primary current.

Ruhmkorff coil was popular for energizing discharge tubes and in particular for generating X-rays (which were discovered in 1895 by Roentgen).

Ruhmkorff’s induction coils were used in many physical experiments when generation of high voltages was needed. This picture shows a very large Ruhmkorff’s induction coil. Ruhmkorff’s doubly wound induction coil later evolved into the alternating-current transformer. He also invented a thermo-electric battery in 1844.

Heinrich D. Ruhmkorff died on December 20, 1877, in Paris.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Sir Charles Wheatstone

Sir Charles Wheatstone was an English physicist and inventor whose work was instrumental in the development of the telegraph in Great Britain. His work in acoustics won him (1834) a professorship of experimental physics at King’s College, London, where his pioneering experiments in electricity included measuring the speed of electricity, devising an improved dynamo, and inventing two new devices to measure and regulate electrical resistance and current: the Rheostat and the Wheatstone bridge named after Wheatstone, as he was the first to put it to extensive and significant use.

Charles Wheatstone was born on 6 February 1802, at Barnwood Manor House, Barnwood, near Gloucester. His father was a music-seller in the town, who, four years later, moved to 128, Pall Mall, London, and became a teacher of the flute. He used to say, with not a little pride, that he had been engaged in assisting at the musical education of the Princess Charlotte.

Charles, the second son, went to a village school, near Gloucester, and afterwards to several institutions in London. One of them was in Kennington, and kept by a Mrs. Castlemaine, who was astonished at his rapid progress. From another he ran away, but was captured at Windsor, not far from the theatre of his practical telegraph.

As a boy he was very shy and sensitive, liking well to retire into an attic, without any other company than his own thoughts. When he was about fourteen years old he was apprenticed to his uncle and namesake, a maker and seller of musical instruments, at 436, Strand, London. However, he showed little taste for handicraft or business, and loved better to study books. His father encouraged him in this, and finally took him out of the uncle’s charge.

At the age of fifteen, Wheatstone translated French poetry, and wrote two songs, one of which was given to his uncle, who published it without knowing it as his nephew’s composition. Some lines of his on the lyre became the motto of an engraving by Bartolozzi. Small for his age, but with a fine brow, and intelligent blue eyes, he often visited an old book-stall in the vicinity of Pall Mall, which was then a dilapidated and unpaved thoroughfare. In 1818, when aged just sixteen, Charles Wheatstone produced his first known new musical instrument, the ‘flute harmonique’, a keyed flute of some kind.

Most of his pocket-money was spent in purchasing the books which had taken his fancy, whether fairy tales, history, or science. One day, to the surprise of the bookseller, he coveted a volume on the discoveries of Volta in electricity, but not having the price, he saved his pennies and secured the volume. It was written in French, and so he was obliged to save again, till he could buy a dictionary.

Then he began to read the volume, and, with the help of his elder brother, William, to repeat the experiments described in it, with a home-made battery, in the scullery behind his father’s house. In constructing the battery the boy philosophers ran short of money to procure the requisite copper-plates. They had only a few copper coins left. A happy thought occurred to Charles, who was the leading spirit in these researches, ‘We must use the pennies themselves,’ said he, and the battery was soon complete.

In September, 1821, Wheatstone brought himself into public notice by exhibiting the ‘Enchanted Lyre,’ or ‘Aconcryptophone,’ at a father-William’s music-shop at Pall Mall and in the Adelaide Gallery. This acoustical trick featured anornate lyre suspended via a thin steel wire from the soundboardsof pianos and other instruments in the room above, and which appearedto play ‘of itself’ by sound conduction and sympathetic resonanceof its strings.

Charles Wheatstone even purported to ‘wind-up’ the Lyre when presenting the show! He speculated publicly at this time on the future transmission of music across London and of it being ‘laid on to one’s house, like gas’. Later, in 1824, he published ‘The Harmonic Diagram’, a musical theory teaching aid.

This illustration shows a demonstration of Wheatstone’s “Enhanced Lyre”, ca. 1821. Musicians played on a piano or harp in the room above the lyre, and the vibrations passed down a brass wire made the lyre appear to play by itself.

At this period Wheatstone made numerous experiments on sound and its transmission. Some of his results are preserved in Thomson’s ANNALS OF PHILOSOPHY for 1823. He recognised that sound is propagated by waves or oscillations of the atmosphere, as light by undulations of the luminiferous ether. Water, and solid bodies, such as glass, or metal, or sonorous wood, convey the modulations with high velocity, and he conceived the plan of transmitting sound-signals, music, or speech to long distances by this means.

He estimated that sound would travel 200 miles a second through solid rods, and proposed to telegraph from London to Edinburgh in this way. He even called his arrangement a ‘telephone.’ Besides transmitting sounds to a distance, Wheatstone devised a simple instrument for augmenting feeble sounds, to which he gave the name of ‘Microphone.’ It consisted of two slender rods, which conveyed the mechanical vibrations to both ears, and is quite different from the electrical microphone of Professor Hughes.

Charles and his brother William took over their uncle Charles’s musical instrument business on his death in autumn 1823, when Charles was 21 and William about 18 years of age. By 1829, Charles and his brother William had moved their business to new premises at 20 Conduit Street, near Bond Street, Regent Street and Hanover Square. Charles Wheatstone and William appear to have maintained their father and uncle’s trade in woodwind and of general musical instrument sales and manufacture.

Charles had no great liking for the commercial part, but his ingenuity found a vent in making improvements on the existing instruments, and in devising philosophical toys. At the end of six years he retired from the undertaking.

In 1827, Wheatstone introduced his ‘kaleidoscope,’ a device for rendering the vibrations of a sounding body apparent to the eye. It consists of a metal rod, carrying at its end a silvered bead, which reflects a ‘spot’ of light. As the rod vibrates the spot is seen to describe complicated figures in the air, like a spark whirled about in the darkness. His photometer was probably suggested by this appliance. It enables two lights to be compared by the relative brightness of their reflections in a silvered bead, which describes a narrow ellipse, so as to draw the spots into parallel lines.

In 1828, Wheatstone improved the German wind instrument, called the MUND HARMONICA, till it became the popular concertina, patented on June 19, 1829 The portable harmonium is another of his inventions, which gained a prize medal at the Great Exhibition of 1851.

Wheatstone’s Concertina

The concertina belongs to a class of instruments known as Free Reed instruments, which also includes accordions and harmonicas. It was developed in 1829 and 1830 by Sir Charles Wheatstone after several years of building prototypes, a few of which still exist (in 1829 he patented its direct predecessor, the Symphonium, but he did not actually patent the concertina itself until 1844). He founded the firm of Wheatstone & Co to manufacture concertinas, each one expensively hand-made by highly skilled craftsmen, and at first the concertina was very much an instrument of the middle and upper class drawing room.

Its fully chromatic range was suited to classical pieces, with its fast action lending it to “party pieces” such as The Flight of the Bumble Bee. In due course other firms such as Lachenal and Jeffries were founded (several by ex-Wheatstone employees) the cost of concertinas lowered, and the instrument moved out of the drawing room and into the world of popular music. Shown on the left is the original concertina as invented by Wheatstone. You can recognise one by the 4 parallel rows of buttons and by the supports for thumb and little finger on each end. The larger baritone and bass English concertinas frequently have wrist straps as well, to help with the greater weight of the instrument.

In the 20th Century the instrument gradually fell out of favour, and one by one the makers closed or went out of business. Wheatstone’s themselves (by this time owned by Boosey & Hawkes) closed in 1968. What saved the instrument from gradually dwindling away into obscurity, as far as the UK was concerned, was the Folk Revival from the ’60s onward. Performers looking for a different sound from the ubiquitous guitar were drawn to the concertina for all its old virtues of versatility and flexibility combined with portability. In addition the concertina permitted song accompaniments that were free of the rhythmic straitjacket that the guitar in unskilled hands tends to impose upon everything. For folk and morris dance the anglo concertina and its accordion cousin the melodeon proved ideal. People started making concertinas again, many of a quality to equal anything made by the old companies.

He also improved the speaking machine of De Kempelen, and endorsed the opinion of Sir David Brewster, that before the end of this century a singing and talking apparatus would be among the conquests of science.

Charles Wheatsone’s refinements of Von Kempelen’s talking machine, late 1800’s

Wheatstone’s construction of von Kempelen’s speaking machine

In 1791 Wolfgang von Kempelen built a device for generating speech utterances. An improved version of the machine was built from von Kempelen’s description by Sir Charles Wheatstone. Briefly, the device was operated in the following manner. The right arm rested on the main bellows and expelled air though a vibrating reed to produce voiced sounds.” (This is illustrated in the lower half of the figure).

“The fingers of the right hand controlled the air passages for the fricatives /sh/ and /s/, as well as the ‘nostril’ openings and the reed on-off control. For vowel sounds, all the passages were closed and the reed turned on. Control of vowel resonances was effected with the left hand by suitably deforming the leather resonator at the front of the device. Unvoiced sounds were produced with the reed off, and by a turbulent flow through a suitable passage. In the original work, von Kempelen claimed that approximately 19 consonant sounds could be made passably well.

In 1834, Wheatstone, who had won a name for himself, was appointed to the Chair of Experimental Physics in King’s College, London, But his first course of lectures on sound were a complete failure, owing to an invincible repugnance to public speaking, and a distrust of his powers in that direction. In the rostrum he was tongue-tied and incapable, sometimes turning his back on the audience and mumbling to the diagrams on the wall. In the laboratory he felt himself at home, and ever after confined his duties mostly to demonstration. Wheatstone had a lifelong friendship with the scientist Michael Faraday (1791-1867), and due to Wheatstone’s intense shyness, Faraday usually delivered Charles’s lectures for him at the Royal Institution.

He achieved renown by a great experiment – the measurement of the velocity of electricity in a wire. His method was beautiful and ingenious. He cut the wire at the middle, to form a gap which a spark might leap across, and connected its ends to the poles of a Leyden jar filled with electricity. Three sparks were thus produced, one at either end of the wire, and another at the middle.

He mounted a tiny mirror on the works of a watch, so that it revolved at a high velocity, and observed the reflections of his three sparks in it. The points of the wire were so arranged that if the sparks were instantaneous, their reflections would appear in one straight line; but the middle one was seen to lag behind the others, because it was an instant later. The electricity had taken a certain time to travel from the ends of the wire to the middle. This time was found by measuring the amount of lag, and comparing it with the known velocity of the mirror. Having got the time, he had only to compare that with the length of half the wire, and he found that the velocity of electricity was 288,000 miles a second.

He also conducted experiments in order to calculate the speed of light and produced a figure of almost 250,000 miles per second – by far the most accurate estimate of that time. Wheatstone’s device of the revolving mirror was afterwards employed by Foucault and Fizeau to measure the velocity of light. Till then, many people had considered the electric discharge to be instantaneous; but it was afterwards found that its velocity depended on the nature of the conductor, its resistance, and its electrostatic capacity. Faraday showed, for example, that its velocity in a submarine wire, coated with insulator and surrounded with water, is only 144,000 miles a second, or still less.

In 1835 Sir Charles Wheatstone read a paper on the ‘Prismatic Analysis of Electric Light’ before the British Association meeting at Dublin. He demonstrated the fact that the spectrum of the electric spark from different metals presented more or less numerous rays of definite refrangibility, producing a series of lines differing in position and colour from each other and that thus the presence of a very minute portion of any given metal might be determined. ‘We have here’, he said, ‘a mode of discriminating metallic bodies more readily than by chemical examination, and which may hereafter be employed for useful purposes’. This remark is very typical of his farsightedness into the practical utility of any known scientific fact. This suggestion has been of great service in spectrum analysis, and as applied by Bunsen, Kirchoff, and others, has led to the discovery of several new elements, such as rubidium and thallium, as well as increasing our knowledge of the heavenly bodies.

Two years later, he called attention to the value of thermo-electricity as a mode of generating a current by means of heat, and since then a variety of thermo-piles have been invented, some of which have proved of considerable advantage.

Electric Telegraph

Wheatstone abandoned his idea of transmitting intelligence by the mechanical vibration of rods, and took up the electric telegraph. In 1835 he lectured on the system of Baron Schilling, and declared that the means were already known by which an electric telegraph could be made of great service to the world. He made experiments with a plan of his own, and not only proposed to lay an experimental line across the Thames, but to establish it on the London and Birmingham Railway.

Sir Charles Wheatstone was not the ‘inventor’ of the telegraph – indeed no-one can really claim that title. The telegraph was advanced by several people starting with Stephen Gray in 1727. However, Sir Charles Wheatstone was the first person with William Cooke to develop a viable system which was made available to the public. Cooke saw the possibilities of a telegraphic system linking the major towns in the country.

But he was unknown to investors. So to get commercial support for his scheme he turned to Professor Charles Wheatstone as partner. It was in 1837 that Cooke & Wheatstone devised the first practical telegraph, which was known as the five needle system. This was an alphabetical system with five needles, controlled by five separate wires. The needles pointed to to the desired letter. It only remained for the receiving operator to note down the letters in order as received.

The five-needle telegraph, which was mainly, if not entirely, due to Wheatstone, was similar to that of Schilling, and based on the principle enunciated by Ampere – that is to say, the current was sent into the line by completing the circuit of the battery with a make and break key, and at the other end it passed through a coil of wire surrounding a magnetic needle free to turn round its centre.

According as one pole of the battery or the other was applied to the line by means of the key, the current deflected the needle to one side or the other. There were five separate circuits actuating five different needles. The latter were pivoted in rows across the middle of a dial shaped like a diamond, and having the letters of the alphabet arranged upon it in such a way that a letter was literally pointed out by the current deflecting two of the needles towards it.

To transmit a letter of the alphabet two switches were pressed which caused two needles to move and point to the appropriate letter. By pressing different combinations of switches any one of twenty letters could be transmitted. Unfortunately J, C, Q, U, X and Z had to be omitted making it difficult to send some words. Alternative methods were adopted to spell words such as “queen”, “quiz” or “axe”. Despite its shortcomings, the advantage of their equipment was that it could be used by unskilled operators.

An experimental line, with a sixth return wire, was run between the Euston terminus and Camden Town station of the London and North Western Railway on July 25, 1837. The actual distance was only one and a half mile, but spare wire had been inserted in the circuit to increase its length.

It was late in the evening before the trial took place. Mr. Cooke was in charge at Camden Town, while Mr. Robert Stephenson and other gentlemen looked on; and Wheatstone sat at his instrument in a dingy little room, lit by a tallow candle, near the booking-office at Euston. Wheatstone sent the first message, to which Cooke replied, and ‘never,’ said Wheatstone, ‘did I feel such a tumultuous sensation before, as when, all alone in the still room, I heard the needles click, and as I spelled the words, I felt all the magnitude of the invention pronounced to be practicable beyond cavil or dispute.’

In spite of this trial, however, the directors of the railway treated the ‘new-fangled’ invention with indifference, and requested its removal. In July, 1839, however, it was favoured by the Great Western Railway, and a line erected from the Paddington terminus to West Drayton station, a distance of thirteen miles. Part of the wire was laid underground at first, but subsequently all of it was raised on posts along the line. Their circuit was eventually extended to Slough in 1841, and was publicly exhibited at Paddington as a marvel of science, which could transmit fifty signals a distance of 280,000 miles in a minute. The price of admission was a shilling.

In 1840 Wheatstone had patented an alphabetical telegraph, or, ‘Wheatstone A B C instrument,’ which moved with a step-by-step motion, and showed the letters of the message upon a dial. The same principle was utilised in his type-printing telegraph, patented in 1841. This was the first apparatus which printed a telegram in type. It was worked by two circuits, and as the type revolved a hammer, actuated by the current, pressed the required letter on the paper. There is a hand generator on the front, a dial with 30 keys round the edge and a pointer. The whole thing was known as a communicator.

A separate receiver also had a single pointer. To work it one pressed the key for the letter wanted and wound the generator. The pointer would go round until it reached the key pressed and then it disconnected the generator. Pressing another key then allowed the pointer to rotate to the next letter and so on. The generator sent alternating half cycles of current to the line and the receiving pointer moved round a letter at a time, like a stepper motor, till it reached the letter being sent. It was pretty simple, robust, and needed little skill to operate. Speeds were up to about 15 words per minute.

Cooke and Wheatstone ABC Telegraph Transmitter

A rare and important ABC Telegraph Transmitter, this fine instrument is from the laboratory of one of the inventors, Professor Charles Wheatstone’s, Kings College Laboratory on the Strand England. “KCL” is stamped on the top of the base and “KCL WB” is stenciled on the bottom.. The wood screws securing the base cover are pre-1856 technology. This instrument has a 7 1/2″ diameter mahogany base supporting a spoked brass wheel on which the alphabet is printed in black lettering on its perimeter.

To operate the instrument, the sender simply rotates the wheel until the desired letter is displayed under the index arm. During rotation the instrument sends out the proper number of electric pulses to an electromagnetically controlled pointer on a remote synchronized slave receiver with a similarly lettered wheel which moves to the sender’s letter. Electric telegraphs of the 1840-50’s are of special historic importance as the earliest practical application of serial binary coded digital communication. They are one of the first bricks in the technology that led to the digital electronic “information highway” evolving today.

Advertisement for a telegraph demonstration, 1839

There were problems in insulating the iron wires which carried the signal. The wires were covered with cotton and buried in iron pipes beside the railway line. While the wires remained dry there was no problem but if they became wet the insulation failed. Nevertheless, the equipment clearly impressed the Directors of the Great Western Railway who allowed a trial to take place between Paddington and West Drayton. The trial was a partial success. The company did not accede to Cooke’s request to extend it to Bristol, but did agree an extension as far as Slough, provided railway messages were carried free of charge.

Cooke overcame the insulation problems by suspending the wires from iron posts using glass insulators. This extension was paid for by Cooke and Wheatstone and to recover some of the expense they offered the public the opportunity to send messages at a shilling (5 p) a time. Although the five needle telegraph was easy to operate it required six wires. It was soon replaced by a single needle instrument. Each letter of the alphabet was given a code of right and left needle movements, and in this way messages could be transmitted. However, this required skilled operators.

Not with standing its success, the public did not readily patronise the new invention until its utility was noised abroad by the clever capture of the murderer Tawell. Between six and seven o’clock one morning a woman named Sarah Hart was found dead in her home at Salt Hill, and a man had been observed to leave her house some time before. The police knew that she was visited from time to time by a Mr. John Tawell, from Berkhampstead, where he was much respected, and on inquiring and arriving at Slough, they found that a person answering his description had booked by a slow train for London, and entered a first-class carriage. The police telegraphed at once to Paddington, giving the particulars, and desiring his capture.

‘He is in the garb of a Quaker,’ ran the message, ‘with a brown coat on, which reaches nearly to his feet.’ There was no ‘Q’ in the alphabet of the five-needle instrument, and the clerk at Slough began to spell the word ‘Quaker’ with a ‘kwa’; but when he had got so far he was interrupted by the clerk at Paddington, who asked him to ‘repent.’ The repetition fared no better, until a boy at Paddington suggested that Slough should be allowed to finish the word. ‘Kwaker’ was understood, and as soon as Tawell stepped out on the platform at Paddington he was ‘shadowed’ by a detective, who followed him into a New Road omnibus, and arrested him in a coffee tavern.

Tawell was tried for the murder of the woman, and astounding revelations were made as to his character. Transported in 1820 for the crime of forgery, he obtained a ticket-of-leave, and started as a chemist in Sydney, where he flourished, and after fifteen years left it a rich man. Returning to England, he married a Quaker lady as his second wife. He confessed to the murder of Sarah Hart, by prussic acid, his motive being a dread of their relations becoming known. Tawell was executed, and the notoriety of the case brought the telegraph into repute. Its advantages as a rapid means of conveying intelligence and detecting criminals had been signally demonstrated, and it was soon adopted on a more extensive scale.

In 1845 Wheatstone introduced two improved forms of the apparatus, namely, the ‘single’ and the ‘double’ needle instruments, in which the signals were made by the successive deflections of the needles. Of these, the single-needle instrument, requiring only one wire, is still in use.

In 1841 a difference arose between Cooke and Wheatstone as to the shareof each in the honour of inventing the telegraph. The question was submitted to the arbitration of the famous engineer, Marc Isambard Brunel, on behalf of Cooke, and Professor Daniell, of King’s College, the inventor of the Daniell battery, on the part of Wheatstone. They awarded to Cooke the credit of having introduced the telegraph as a useful undertaking which promised to be of national importance, and to Wheatstone that of having by his researches prepared the public to receive it. They concluded with the words: ‘It is to the united labours of two gentlemen so well qualified for mutual assistance that we must attribute the rapid progress which this important invention has made during five years since they have been associated.’ The decision, however vague, pronounces the needle telegraph a joint production.

If it was mainly invented by Wheatstone, it was chiefly introduced by Cooke. Their respective shares in the undertaking might be compared to that of an author and his publisher, but for the fact that Cooke himself had a share in the actual work of invention. The introduction of the telegraph had so far advanced that, on September 2, 1845, the Electric Telegraph Company was registered, and Wheatstone, by his deed of partnership with Cooke, received a sum of L33,000 for the use of their joint inventions.

From 1836-1837 Wheatstone had thought a good deal about submarine telegraphs, and in 1840 he gave evidence before the Railway Committee of the House of Commons on the feasibility of the proposed line from Dover to Calais. He had even designed the machinery for making and laying the cable.

In the autumn of 1844, with the assistance of Mr. J. D. Llewellyn, he submerged a length of insulated wire in Swansea Bay, and signalled through it from a boat to the Mumbles Lighthouse. Next year he suggested the use of gutta-percha for the coating of the intended wire across the Channel.

Though silent and reserved in public, Wheatstone was a clear and voluble talker in private, if taken on his favourite studies, and his small but active person, his plain but intelligent countenance, was full of animation. Sir Henry Taylor tells us that he once observed Wheatstone at an evening party in Oxford earnestly holding forth to Lord Palmerston on the capabilities of his telegraph. ‘You don’t say so!’ exclaimed the statesman. ‘I must get you to tell that to the Lord Chancellor.’ And so saying, he fastened the electrician on Lord Westbury, and effected his escape.

A reminiscence of this interview may have prompted Palmerston to remark that a time was coming when a minister might be asked in Parliament if war had broken out in India, and would reply, ‘Wait a minute; I’ll just telegraph to the Governor-General, and let you know.’

In 1840 Wheatstone also brought out his magneto-electrical machine for generating continuous currents, and his chronoscope, for measuring minute intervals of time, which was used in determining the speed of a bullet or the passage of a star.

The same year he was awarded the Royal Medal of the Royal Society for his explanation of binocular vision, a research which led him to construct the stereoscope. He showed that our impression of solidity is gained by the combination in the mind of two separate pictures of an object taken by both of our eyes from different points of view. Thus, in the stereoscope, an arrangement of lenses and mirrors, two photographs of the same object taken from different points are so combined as to make the object stand out with a solid aspect.

The ‘pseudoscope’ (Wheatstone was partial to exotic forms of speech) was introduced by its professor in 1850, and is in some sort the reverse of the stereoscope, since it causes a solid object to seem hollow, and a nearer one to be farther off; thus, a bust appears to be a mask, and a tree growing outside of a window looks as if it were growing inside the room. It was eleven years later before Sir David Brewster described a binocular camera, and the first stereoscopic photographs began to be produced.

We’ve all enjoyed 3D movies and stared at 3D pictures (stereograms) on walls – well, the first real stereographer was Sir Charles Wheatstone, who made geometric 3-D drawings and a device to view them called a reflecting mirror stereoscrope in 1838. This proved that stereo perception was a result of binocular vision. Wheatstone’s actual stereoscope is preserved at the Science Museum in London.

On November 26, 1840, he exhibited his electromagnetic clock in the library of the Royal Society, and propounded a plan for distributing the correct time from a standard clock to a number of local timepieces. The circuits of these were to be electrified by a key or contact-maker actuated by the arbour of the standard, and their hands corrected by electro-magnetism.

The following January Alexander Bain took out a patent for an electromagnetic clock, and he subsequently charged Wheatstone with appropriating his ideas. It appears that Bain worked as a mechanist to Wheatstone from August to December, 1840, and he asserted that he had communicated the idea of an electric clock to Wheatstone during that period; but Wheatstone maintained that he had experimented in that direction during May. Bain further accused Wheatstone of stealing his idea of the electromagnetic printing telegraph; but Wheatstone showed that the instrument was only a modification of his own electromagnetic telegraph.

In 1843 Wheatstone communicated an important paper to the Royal Society, entitled ‘An Account of Several New Processes for Determining the Constants of a Voltaic Circuit.’ It contained an exposition of the well- known balance for measuring the electrical resistance of a conductor, which still goes by the name of Wheatstone’s Bridge or balance.

Wheatstone Bridge

The Wheatstone bridge is an electrical circuit for the precise comparison of resistances. Sir Charles Wheatstone is most famous for this device but never claimed to have invented it – however, he did more than anyone else to invent uses for it, when he “found” the description of the device in 1843. The first description of the bridge was by Samuel Hunter Christie (1784-1865), of the Royal Military Academy, who published it in the PHILOSOPHICAL TRANSACTIONS for 1833.

The Wheatstone bridge is an electrical bridge circuit used to measure resistance. It consists of a common source of electrical current (such as a battery) and a galvanometer that connects two parallel branches, conta ining four resistors, three of which are known. One parallel branch contains one known resistance and an unknown (R4 in the left example); the other parallel branch contains resistors of known resistances. In order to determine the resistance of the unknown resistor, the resistances of the other three are adjusted and balanced until the current passing through the galvanometer decreases to zero.

The method was neglected until Wheatstone brought it into notice. His paper abounds with simple and practical formula: for the calculation of currents and resistances by the law of Ohm. He introduced a unit of resistance, namely, a foot of copper wire weighing one hundred grains, and showed how it might be applied to measure the length of wire by its resistance.

He was awarded a medal for his paper by the Society. The same year he invented an apparatus which enabled the reading of a thermometer or a barometer to be registered at a distance by means of an electric contact made by the mercury.

One of Wheatstone’s most ingenious devices was the ‘Polar clock,’ exhibited at the meeting of the British Association in 1848. It is based on the fact discovered by Sir David Brewster, that the light of the sky is polarised in a plane at an angle of ninety degrees from the position of the sun. It follows that by discovering that plane of polarisation, and measuring its azimuth with respect to the north, the position of the sun, although beneath the horizon, could be determined, and the apparent solar time obtained.

The clock consisted of a spy-glass, having a nichol or double-image prism for an eye-piece, and a thin plate of selenite for an object-glass. When the tube was directed to the North Pole–that is, parallel to the earth’s axis–and the prism of the eye-piece turned until no colour was seen, the angle of turning, as shown by an index moving with the prism over a graduated limb, gave the hour of day. The device is of little service in a country where watches are reliable; but it formed part of the equipment of the North Polar expedition commanded by Captain Nares.

Wheatstone’s remarkable ingenuity was displayed in the invention of cyphers which have never been unravelled, and interpreting cypher manuscripts in the British Museum which had defied the experts. He devised a cryptograph or machine for turning a message into cypher which could only be interpreted by putting the cypher into a corresponding machine adjusted to reproduce it.

The Playfair Cipher

The Playfair cipher is a substitution cipher bearing the name of the man who popularized but not created it. This method was invented by Sir Charles Wheatstone, in around 1854, however he named his invention after his goodfriend, Lyon Playfair, the first Baron Playfair St. Andrews. Wheatstone named this method after his friend, because he was more well known to the public. Playfair was a scientist and a public figure of Victorian England. He also was “at one time or another deputy speaker of the House of Commons, Postmaster General, and President of the British Association for theAdvancement of Science”. Playfair demonstrated what he called “Wheatstone’s newly discovered symmetrical cipher”, at a dinner in January of 1854, to associates in the British Aristocracy as well as in the Foreign office. The Playfair cipher was developed for telegraph secrecy and it was the first literal digraph substitution cipher.

It was used by Britians forces in the Boer War and World War I and also by the islands of Coastwatching in Australia during World War II. This method is quite easy to understand and learn, but not that easy to break, because you would need to know the “keyword” to decipher the code. The system functions on how the letters are positioned in relationship to a 5×5 alphabet matrix. A “KEYWORD” sets the pattern of letters with the other letters entered in the cells of the matrix in alphabetical order (i and j are usually combined in one cell). For instance, suppose we use the keyword “charles” then the matrix would look like this:

Now supposing the message to be enciphered here is “the scheme really works”.

First of all the plaintext is divided into two-letter groups. If there are double letters occuring, in the message, either an ‘x’ will be used to seperate the double letters or an ‘x’ will be added to make a two-letter group combination. In our example, the phrase beomes:

Each of the above two letter combinations will have 3 possible relationships with eachother in the matrix: they can be in the same column, same row, or neither. The following rules for replacement should be used:

If the two letters are in the sme column of the matrix, use the letter below it as the cipher text (columns are cyclical).

If the two letters are in the same row of the matrix, use the letter to the right as the cipher text (rows are cyclical).

If neither the same column or row, than each are exchanged with the letter at the intersection of its own row and the other column.

For deciphering, the rules are the exact opposite.

The rapid development of the telegraph in Europe may be gathered from the fact that in 1855, the death of the Emperor Nicholas at St. Petersburg, about one o’clock in the afternoon, was announced in the House of Lords a few hours later; and as a striking proof of its further progress, it may be mentioned that the result of the Oaks of 1890 was received in New York fifteen seconds after the horses passed the winning-post.

Wheatstone’s next great invention was the automatic transmitter, in which the signals of the message are first punched out on a strip of paper, which is then passed through the sending-key, and controls the signal currents. By substituting a mechanism for the hand in sending the message, he was able to telegraph about 100 words a minute, or five times the ordinary rate. In the Postal Telegraph service this apparatus is employed for sending Press telegrams, and it has recently been so much improved, that messages are now sent from London to Bristol at a speed of 600 words a minute, and even of 400 words a minute between London and Aberdeen. On the night of April 8, 1886, when Mr. Gladstone introduced his Bill for Home Rule in Ireland, no fewer than 1,500,000 words were despatched from the central station at St. Martin’s-le-Grand by 100 Wheatstone transmitters.

Wheatstone’s Paper Tape to Store Data

In 1837, the American inventor Samuel Morse developed the first American electric telegraph, which was based on simple patterns of “dots” and “dashes” called Morse Code being transmitted over a single wire. The telegraph quickly proliferated thanks to the relative simplicity of Morse’s system. However, a problem soon arose in that operators could only transmit around ten words a minute, which meant that they couldn’t keep up with the public’s seemingly insatiable desire to send messages to each other. This was a classic example of a communications bottleneck.

Thus, in 1857, only twenty years after the invention of the telegraph, Sir Charles Wheatstone introduced the first application of paper tapes as a medium for the preparation, storage, and transmission of data. Sir Charles’ paper tape used two rows of holes to represent Morse’s dots and dashes. Outgoing messages could be prepared off-line on paper tape and transmitted later. By 1858, a Morse paper tape transmitter could operate at 100 words a minute. Unsuspectingly, Sir Charles had also provided the American public with a way to honor their heroes and generally have a jolly good time, because used paper tapes were to eventually become a key feature of so-called ticker-tape parades.

In a similar manner to Sir Charles’ telegraph tape, the designers of the early computers realized that they could record their data on a paper tape by punching rows of holes across the width of the tape. The pattern of the holes in each data row represented a single data value or character. The individual hole positions forming the data rows were referred to as “channels” or “tracks,” and the number of different characters that could be represented by each row depended on the number of channels forming the rows.

In 1859 Wheatstone was appointed by the Board of Trade to report on the subject of the Atlantic cables, and in 1864 he was one of the experts who advised the Atlantic Telegraph Company on the construction of the successful lines of 1865 and 1866.

On February 4, 1867, he published the principle of reaction in the dynamo-electric machine by a paper to the Royal Society; but Mr. C. W. Siemens had communicated the identical discovery ten days earlier, and both papers were read on the same day.

It afterwards appeared that Herr Werner Siemens, Mr. Samuel Alfred Varley, and Professor Wheatstone had independently arrived at the principle within a few months of each other. Varley patented it on December 24, 1866; Siemens called attention to it on January 17, 1867; and Wheatstone exhibited it in action at the Royal Society on the above date. But it will be seen from our life of William Siemens that Soren Hjorth, a Danish inventor, had forestalled them.

In 1870 the electric telegraph lines of the United Kingdom, worked by different companies, were transferred to the Post Office, and placed under Government control.

At Christchurch, Marylebone, on February 12, 1847, Wheatstone was married. His wife, Emma, was the daughter of J. West, a Taunton tradesman. She died in 1866, leaving a family of five young children to his care. His domestic life was quiet and uneventful.

Wheatstone was knighted 30 Jan. 1868 1868, after his completion of the automatic telegraph. He had previously (1855) been made a Chevalier of the Legion of Honour. Some thirty-four distinctions and diplomas of home or foreign societies bore witness to his scientific reputation. Since 1836 he had been a Fellow of the Royal Society, and in 1873 he was appointed a Foreign Associate of the French Academy of Sciences. The same year he was awarded the Ampere Medal by the French Society for the Encouragement of National Industry. In 1875 he was created an honorary member of the Institution of Civil Engineers. On 2 July 1862 he was created D.C.L. by the university of Oxford, and in l864 L.L.D. by the University of Cambridge.

While on a visit to Paris during the autumn of 1875, and engaged in perfecting his receiving instrument for submarine cables, he caught a cold, which produced inflammation of the lungs, an illness from which he died in Paris, on October 19, 1875, aged 73. A memorial service was held in the Anglican Chapel, Paris, and attended by a deputation of the Academy. His remains were taken to his home in Park Crescent, London, and buried in the cemetery at Kensal Green.

He left his collection of books and instruments by will to King’s College, London where they are preserved in the Wheatstone Laboratory. Wheatstone contributed to numerous scientific journals and publications. All his published papers were collected in one volume and published in 1879 by the Physical Society of London.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Thomas Davenport

Thomas Davenport was an American blacksmith and inventor who invented the first DC electrical motor in 1834 and made a small model of electrical railway in 1835. He patented a device for “Improvements in propelling machinery by magnetism and electromagnetism” in 1837 (his electric railway). Davenport used his DC electrical motor to power shop machinery, it was the first practical application for the electric motor. Davenport later started a workshop in New York City and published a journal on electromagnetism.

Thomas Davenport from a daguerreotype of about 1850 reprinted from Franklin Leonard Pope, “The Inventors of the Electric Motor”, The Electrical Engineer 11 (7 January 1891) 3.

Thomas Davenport was born in 1802 in Vermont on a farm outside Williamstown, Vt., the eighth of 12 children. His father died when Thomas was 10. Schooling opportunities were minimal, and at the age of 14 Thomas was indentured for seven years to a blacksmith. His room and board and six weeks per year of rural schooling were provided in return for service in his master’s shop. The work was hard, but the boy was later remembered for his curiosity, his interest in musical instruments, and his passion for books.

Once he was liberated in 1823, Davenport traveled over the Green Mountains to Forestdale, a hamlet in the town of Brandon, Vt., where there was an iron industry. He set up his own marginally successful shop, married Emily, a daughter of Rufus Goss, a local merchant, and started a family.

His only means of learning was self-education. When the news from the ironworks piqued his curiosity, he acquired books and journals, and started reading about the experiments and discoveries that were beginning to unlock some of the mysteries of electricity and magnetism.

In the spring of 1833 Thomas Davenport heard some curious news. This news, as it turned out, would not only change his life but would eventually change the life of almost everyone on earth. The momentous news that roused the blacksmith’s curiosity was that the Penfield and Hammond Iron Works, on the other side of Lake Champlain in the Crown Point hamlet of Ironville in New York state, was using a new method for separating crushed ore.

The process used magnetized spikes mounted on a rotating wooden drum that attracted the millings with the highest iron content. Higher-purity feedstock could be fed to the furnaces, improving their productivity and the quality of the iron they produced. This was important, since the recent introduction and expected rapid expansion of railroads were dramatically increasing the demand for quality iron.

This process had been developed by Joseph Henry of Albany, N.Y. It used an electromagnet that he had designed to magnetize the spikes; in fact, Henry’s electromagnet was said to be powerful enough to lift a blacksmith’s anvil. Its use in the iron ore separation process was the first time that electricity had been used for commercial purposes, thus beginning the electric industry. Thomas Davenport had no prior knowledge of discoveries in magnetism and electricity when this new process stimulated his interest.

Soon after he learned of the Henry magnet, Davenport traveled the 25 miles to Crown Point on a horse to witness the wonders of magnetic lifting power. The amazing sight further inflamed his interest. He decided to travel another 80 miles south, to Albany, to meet Henry, only to find out that he had moved down to Princeton. Returning home out of money, Davenport called upon his brother, a peddler, to join him with his cart for another trip to Crown Point. Once there, they auctioned the brother’s products and traded a good horse for an inferior one to obtain money to buy the magnet. When they got home, the brother suggested trying to recover the cost by exhibiting the magnet for a fee.

Thomas Davenport had other plans. He unwound and dismantled the magnet as his wife, Emily, took notes on its method of construction. He then started his own experiments and built two more magnets of his own design. Insulated wire was required, but only bare wire was available. Emily Davenport cut up her wedding dress into strips of silk to provide the necessary insulation that allowed for the maximum number of windings.

The electricity source for the magnets was a galvanic battery of the type developed by Volta. It used a bucket of a weak acid for an electrolyte. The bucket contained concentric cylinders of different metals for electrodes; these were wired to provide external electric current to the magnet.

Davenport mounted one magnet on a wheel; the other magnet was fixed to a stationary frame. The interaction between the two magnets caused the rotor to turn half a revolution. He learned that by reversing the wires to one of the magnets he could get the rotor to complete another half-turn. Davenport then devised what we now call a brush and commutator. Fixed wires from the frame supplied current to a segmented conductor that supplied current to the rotor-mounted electromagnet. This provided an automatic reversal of the polarity of the rotor-mounted magnet twice per rotation, resulting in continuous rotation.

The motor had the potential to drive some of the equipment in Davenport’s shop, but he had even bigger ideas. The era of the steam locomotive and railroads was just beginning, but already boiler failures and explosions were becoming frequent, tragic occurrences. Davenport’s solution was the electric locomotive. He built a model electric train that operated on a circular track 4 feet in diameter; power was supplied from a stationary battery to the moving electric locomotive using the rails as conductors to transmit the electricity.

When Davenport traveled to Washington to obtain a patent, however, his application was rejected: There were no prior patents on electric equipment. He started a tour of colleges to meet professors of natural philosophy who might examine his invention and provide letters of support to the patent office. His travels took him to the new Rensselaer Institute in Troy, N.Y., recently founded (in 1824) as the nation’s first engineering school by Stephen Van Rensselaer.

This Patent Office model of Davenport’s motor now sits in The Smithsonian Institution in Washington.

The last of eight generations of land-owning patroons, Van Rensselaer had been a commissioner overseeing the construction of the Erie and Champlain canals, opened in 1825. The school had been charged with a mission to qualify teachers for instructing the sons and daughters of farmers and mechanics in developing methods of applying science to the common purposes of life.

Davenport met Rensselaer’s founding president, Amos Eaton, a distinguished lawyer, botanist, geologist, chemist, educator, and innovator, who was amazed by the motor and by the self-educated blacksmith who had built it. Eaton arranged an additional exhibit for the citizens of Troy, and Stephen Van Rensselaer himself bought Davenport’s motor for the school. The nation’s first engineering school now possessed the world’s first electric motor.

After refining the machine, Davenport and Smalley (Davenport’s friend and assistant) demonstrated their “electromagnetic engine” to Professor Turner of Middlebury College at Middlebury, Vermont, in December of 1834. In a handwritten note of January 5, 1835, Professor Turner described “Davenport and Smalley’s Specification of their Invention of an Electro-Magnetic Machine.” His description of the invention was illustrated with the drawing shown here.

With the sale of his motor, Davenport was able to buy a quantity of already insulated wire, and he returned home to build another motor. He traveled to Princeton to meet Joseph Henry and then to the University of Pennsylvania to meet Professor Benjamin Franklin Bache, Benjamin Franklin’s grandson and an outstanding scientist.

The self-educated blacksmith, having now impressed the most prominent men of learning in the country, returned to the patent office with letters and a working model. His troubles were not yet over, however. The model was destroyed by fire before it was examined. He built another and tried again. At last, the first patent on any electric machine was issued to Thomas Davenport for his electric motor on February 25, 1837.

A page with the drawings from the Davenport’ patent of February 25, 1837.

The scientific community and the media responded with great excitement and high expectations. Benjamin Silliman, the founder of Silliman’s Journal of Science, wrote an extended article and concluded that a power of great but unknown energy had unexpectedly been placed in mankind’s hands. The New York Herald proclaimed a revolution of philosophy, science, art, and civilization: “The occult and mysterious principle of magnetism is being displayed in all of its magnificence and energy as Mr. Davenport runs his wheel.”

Davenport set up a laboratory and workshop near Wall Street in hopes of attracting investors. Samuel Morse, who in 1844 would commercialize the telegraph, came to observe. To further advertise his motor, Davenport established his own newspaper, “The Electro-Magnet and Mechanics Intelligencer”, and used his electric motor to drive his rotary printing press.

The motor was a spectacular technological success, but it was becoming a commercial failure. No one knew how to predict the amount of energy in chemical batteries, and a battery-powered motor could not compete with a steam engine. Funds were promised but not delivered. Bankrupt and distressed, Davenport returned to Vermont and started writing a book describing his work and his vision for his electric motor. He died in 1851 just three days before his 49th birthday, leaving only a prospectus.

What Davenport could not anticipate, and what no one else would describe for another 20 years, was that his motor would be turned by water or steam power and would operate in reverse, as an electric generator. Within 40 years of his death, electric-powered trains and trolleys had become common, with Davenport’s machine creating electricity at the power station and his motor then converting this electricity back to mechanical power to move the cars. In 1882, his Pearl Street station in lower Manhattan used steam engines to drive shunt-wound brush and commutator dc generators of the type that Thomas Davenport had invented 45 years earlier. Recognizing that expanding demand would require a massive new manufacturing and service industry, Edison started a manufacturing facility in Schenectady that would become the General Electric Co. The company’s first products were motors and generators that copied the design and principles of Thomas Davenport’s motor.

Davenport the blacksmith was a bridge between the age of muscle power and the new era of electrical machinery. Not only were his inventions significant, but he was among the first to recognize that electricity would change everything. He deserves to be remembered as one of the great leaders of modern technology.

Interest in the achievements of Thomas Davenport grew during the late 1890s and early 1900s as the significance of the electric motor finally became generally recognized. The Vermont Electrical Association and the National Electric Light Association observed “Davenport Day” on September 28, 1910, in conjunction with the Vermont Historical Association. A large marble block with a bronze plaque commemorating Thomas Davenport was unveiled at the celebration.

Thomas Davenport died on July 6, 1851 , Salisbury, Vt., U.S.A.

In 1929, Rev. Walter Rice Davenport, nephew of Thomas Davenport, wrote the Biography of Thomas Davenport, “The Brandon Blacksmith, Inventor of the Electric Motor”, which was published by the Vermont Historical Society. The book presents a sentimental account of Thomas Davenport’s life, based largely on an autobiographical manuscript written by Thomas Davenport in 1849.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Moritz Hermann Jacobi

Moritz Hermann Jacobi was a German physicist and engineer, but he worked mainly in Russia. His works on galvanoplastics, electric motors, and wire telegraphy were of great applied significance. Moritz Hermann Jacobi was a German physicist and engineer. He was born om September 21, 1801, in Potsdam, Germany. Jacobi graduated from the Getingen University and in 1834 he moved to Kenigsberg where he worked as an architect.

In 1835 Jacobi received professorship at the Derpt University, but two years later, in 1937, he decided to move to St. Petersburg. Jacobi worked as a leading researcher at the Academy of Sciences in St. Petersburg alongside others such as the chemist Mendeliev. Jacobi was one of a rising number of physicists working on the practical applications of electricity, and engaged in a number of studies of great interest in the fast developing subject.

Jacobi’s first electro-motor

In his first work, reported to the St Petersburg Academy, he described his investigation of the power of an electromagnet in relation to the design of motors and generators, and discussed his efforts to construct the first full-scale practical motor in May 1834. He carried out a number of tests on the motor for instance measuring its output by determining the amount of zinc consumed by the battery.

In 1838 Jacobi discovered galvanoplastics (also called electrotyping) and through his success and the presentations he gave, he promoted this specialist field and the application of galvanoplastics and electroplating in Europe. This medal is memorizing Jacobi’s contribution to the development of galvanoplastics.

Electrotyping is electroforming process for making duplicate plates for relief, or letterpress, printing. The process was first announced in 1838 by M.H. von Jacobi, a German working in St. Petersburg, Russia. Thomas Spencer and C.J. Jordan of England and Joseph A. Adams of the United States produced similar results the following year.

An electrotype, or electro, is made by electroplating a thin shell of copper or other metal onto a mold, usually wax, of the original cut or type form and then removing the mold and backing the shell with metal. More durable than type and cuts, electros are used instead of the original for long press runs, to avoid wear and damage to expensive type and halftones or linecuts. Electrotypes also can duplicate and replace linoleum cuts, woodcuts, and wood engravings.

Portraits of Moritz Hermann Jacobi

In 1839 Jacobi, with the financial assistance of Czar Nicholas, constructed a 28-ft boat propelled by an electric motor with a large number of battery cells. It carried 14 passengers on the Neva River at a speed of three miles per hour. His hopes of covering the Neva with a fleet of magnetic boats were doomed from the beginning, however, by the cost of battery-powered operation and by the fumes that such batteries emitted.

In the course of these experiments, he considered how much power he could get out of a battery. A battery can be represented as an electromotive force E in series with an internal resistance R which are about constant and do not depend much on the current that is drawn. If the external load is a resistance R’, then the current is I = E / (R + R’). The power dissipated in the load is I2R’, while the power dissipated in the battery is I2R. If R’ = 0, there is no external power. If R’ is infinitely large there is also no power, since I = 0.

Therefore, for some intermediate value of R’ there must be a maximum power. Calculus gives the result easily, but a little reasoning also shows that maximum power is attained when R’ = R (imagine interchanging R and R’). Hence the theorem: Maximum power is transferred when the internal resistance of the source equals the resistance of the load. We should carefully note the condition that is seldom added: When the external resistance can be varied, and the internal resistance is constant.

Jacobi quite correctly concluded that electric motors were uneconomic, considering the high price of zinc and the 50% loss of energy. The concept of energy was as yet somewhat hazy, and the fact that mechanical work out was equal to the electrical work done against a counter-emf was unknown, at the time. However, it was adopted as a maxim that the internal resistance equaled the load resistance for maximum power.

Jacobi was influenced by the earlier theoretical discoveries of Georg Ohm, and the work of his contemporaries Michael Faraday and Emil Lenz, and in turn his work influence James Joule. Jacobi’s discovery of the counter-induction effect which set a limit to the efficiency of electromagnetic engines led Joule to calculate to his dismay that the efficiency of the electromagnetic engines that he could build would be much lower that of the existing steam engine.

Jacobi’s publications include: “Benutzung der Naturkrafte zu menschichen Arbeiten” (1834); “Ueber die Construction schief liegender Raderwerke” (“Crelle’s Journal der Math.”, 1827); “Ueber den Einfluss der Chausseen, Eisenbahnen und Wasserverbindungen auf den Nationalreichtum” (ib.); “Memoire sur une machine magnetiqne”. “Comptes Rendus”, 1874); “Memoire sur l’application de l’Electromagnetisme au Mouvement des machines” (1835); “Eine Methode die Constanten der Voltschen Ketten zu bestimmen” (“Bull. de l’Acad.”, 1842); “Beschreibung eines verbesserten Voltagometers” (ib.); “Ueber die Entwickelung der Galvanoplastik” (ib., 1843); “Ueber die galvanische Vergoldung” (ib.); “Einige Notizen uber galvanische Leitungen” (ib.); “Ueber die Gesetze der Electromagnete” (mit Lenz), (ib., 1844); “Notice preliminaire sur telegraph electromagnetique entre St.-Petersburg und Tsarskoie-Selo” (ib.); “Ueber galvanische Messing-Reduction” (ib.); “Galvanische und electromagnetische Versuche” (ib., 1845 – 47, 1848 – 50); “Vorlaufige Notiz uber galvanoplastische Reduction mittelst einer magneto-electrischen Maschine” (ib., 1847); “Ueber eine Vereinfachung der Uhrwerke, welche zur Hervorbrin gung einer gleichformigen Bewegung bestimmt ist” (ib., 1848); “Sur les telegraches electriques” (ib., 1849); “Sur la theorie des machines electromagnetiques” (ib., 1851); “Die galvanische Pendeluhr” (ib.); “Sur la necessite d’exprimer la force des courants electriques et la resistance des circoits en unites unanimement et generalement adoptees” (ib., 1858); “Sur quelques experiences concernant la mesure des resistances” (ib., 1859); “Note sur la production de depots de fer galvanique” (ib., 1869); “Confection d’etalons prototypes, destines a generaliser le systeme metriques” (“Comptes Rendus”, 1869); “Notice sur l’absortion de l’hydrogene par le fer galvanique” (“Bul. de l’Acad.”, 1870); “Application des batteries secundaires ou de polarisation aux moteurs electromagnetiques” (ib., 1871); “Sur la fabrication des etalons de longeur la galvanoplastie” (ib., 1872); “Une reduction du fer par l’action d’un puissant solenoide electromagnetique” (ib., 1873); “Courants d’induction dans les bobines d’un electro-aimant, entre les poles duquel un disque metallique est mis en mouvement” (“Comptes Rendus”, 1872). He also published some books in Russian.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Auguste-Arthur de La Rive

Auguste-Arthur De La Rive was a Swiss physicist, one of the founders of the electrochemical theory of batteries. He explained the rotatory movements observed at the time of the aurorae boreales by the influence of the terrestrial magnetism. Auguste-Arthur De La Rive was a Swiss physicist, one of the founders of the electrochemical theory of batteries. Father of Auguste De La Rive was the fervent freedom fighter Charles Gaspard De La Rive (1770-1834) which fled sentenced to death to Scotland, returned later, however, to Geneva and prepared there a modern lab.

Auguste De La Rive got to know the chemist Michael Faraday (1791-1867), during visit with his father, at the age of 13 years. A deep lifelong friendship arose in run of the time from this acquaintance. Guest of his father was also an Andre Marie Ampere (1775 – 1836), so Auguste De La Rive knew the famous scientific researches of his time already in his childhood.

De La Rive began experimenting with the voltaic cell (1836) and supported the idea of Michael Faraday that the electricity was the result of chemical reactions in the cell. During his scientific career he designed an electrochemical condenser (1843); studied electricity and magnetism, presented a double current theory; opposed the contact theory of electricity (contact by 2 dissimilar metals) because he insisted that the only source of electrification was chemical; studied electricity passing through gases, and demonstrated that ozone is formed by electrical sparks in pure oxygen. He invented a prize-winning electroplating method to apply gold onto brass and silver.

He determined the specific heat of various gases and examined the temperature of the Earth’s crust. De La Rive was a contemporary of Faraday, Ampere and Oersted, with whom he exchanged correspondance on electricity. He spent his life in England, France, and Switzerland. De La Rive was editor of science journals, and member of English and French scientific organizations. De La Rive also wrote a three-volume treatise on electricity, titled: “A Treatise on Electricity: In Theory and Practice”, which was translated into the English language. De La Rive taught from 1823 to 1836 as a professor of physics in colleges in Geneva, London and Paris. Later he gave up his professorship and devoted himself to politics and was also active as a scientific writer.

The first attempt to make a practicable incandescent lamp was probably made by Arthur de la Rive in 1820. He used a platinum filament in a partial vacuum.

As a demonstration to explain the rotatory movements observed at the time of the aurorae boreales by the influence of the terrestrial magnetism, De La Rive assembled an apparatus using an egg-shaped evacuated glass chamber on an electromagnet. The instrument is powered by a Ruhmkorff coil and connected to a pneumatic pump, and demonstrates the rotatory effect of a magnetic field on an electric discharge in a rarefied gas. De La Rive’s electric theory stated that the aurora, being influenced by the earth’s magnetic field, would take place in the polar regions through processes of discharge between the positive electricity concentrated in the upper regions of the atmosphere and the negative electricity of the Earth. De la Rive’s theoretical hypothesis was more credible due to the observation, in that period, of a kind of rotational movement of the aurora borealis.

The instrument rests upon a solid circular mahogany base and vertically supports a magnet and an egg-shaped glass ball. In the upper part, the ball is a pair of brass taps: the one that is placed higher produces a first vacuum with a pneumatic machine; the other is used to introduce some drops of ether or of turpentine oil into the ball and then, with the pneumatic machine, to achieve an extremely rarefied vapour.

A soft iron rod is contained in the air-tight glass egg for 3/4 of its height and is connected to a polar expansion iron electromagnet at the base of the glass egg. Except for its extremities, the iron rod is entirely covered by a glass tube that is insulated by a layer of shellac. The part of the glass tube that is inside the egg is wrapped by a copper ring on the bottom and enclosed by an iron lid on top. A pair of brass rheofores, positioned halfway up the device, electrically connect the copper ring with the iron lid. A second pair of brass rheofores, on the mahogany base of the instrument, provides for the energy supply to the electro-magnet.

A beam of light is produced within the glass egg by supplying only the copper ring and the cylinder’s iron lid protecting the rod. The beam is more or less regular and is spread all around the rod, as was the case in the experiment of the electric egg. By supplying the electro-magnet as well, the phenomenon changes, and the dispersed light concentrates in only one beam of light that starts rotating slowly around the poles of the magnetised cylinder, alternating the direction of its rotation according to the direction of the induced current, is manually reversible through a Ruhmkorff commutator on the base of the instrument.

An electron discharge starts at a wire at the top of the tube and trails down to a ring at the bottom. When a cylindrical bar magnet at the center of the tube is activated by a 5-volt power supply the discharge precesses around the magnet. This demonstates the rotation of a vacuum discharge streamer under the influence of a magnetic field.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Carl August von Steinheil

Carl August von Steinheil was a Swiss physicist who is known for his electric clock, telegraph device and optical instruments, particularly telescopes with silver covered mirrors.

Steinheil’s telegraph

In 1836 Steinheil devised a recording telegraph, in which the movable needles indicated the message by marking dots and dashes with printer’s ink on a ribbon of travelling paper, according to an artificial code in which the fewest signs were given to the commonest letters in the German language. With this apparatus the message was registered at the rate of six words a minute.

In 1839, the first electric clock is built by physicist Carl August Steinheil.

Steinheil was one of the first two (simultaneously with but independently of Foucault) to apply silvering to astronomical mirrors, in 1856.

Carl August Steinheil developed numerous physical instruments including spectroscopes. This picture shows a spectroscope constructed by Steinheil in ca. 1895.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Joseph Saxton

Joseph Saxton was a notable American inventor of the first half of the nineteenth century. He had built one of the first magnetoelectrical machines capable of producing electrical sparks.

Joseph Saxton was born in Huntington, PA, March 22, 1799; son of James and Hannah (nee Ashbaugh) Saxton. He attended elementary school until he was 12 years of age at which time he began working in his father’s nail factory. Saxton did not like factory work so apprenticed locally for two years in clockmaking and silversmithing. At this time he constructed a printing-press, and published a small newspaper at irregular intervals.

He moved to Philadelphia in 1818 to receive further training in horology and engraving. While working for the machinist Isaiah Lukens in Philadelphia, Saxton built a pyrometer with an optical lever for measuring the thermal expansion of metal that’s principle he would apply in several other designs, including the reflecting length comparator that he designed and built later working at the Office of Weight and Measures (OWM). Saxton worked in Philadelphia for two different shops before establishing his own engraving and watch making business. During this time he invented a machine for cutting the teeth of wheels, the outlines of which were true epicycloidal curves.

After 11 years of instrument making with distinction in Philadelphia where he received awards for his skill in clockmaking. With Isaiah Lukens he constructed an ingenious clock which gave the movements of the planets, and he also made the town clock placed in the belfry of Independence Hall, Philadelphia (shown left).

In his ambition to obtain knowledge he became a member of the Franklin institute, and acquired reputation among its members for his ingenuity. About 1828 he went to London to design, build, and market innovative instruments. There he became associated with the Adelaide Gallery of Practical Science, for which he constructed several mechanical toys. He there met Telford, Brunel, Whitwell, Hawkins and Faraday, through whose influence he was admitted to the meetings of the Royal institution.

In December 1832, he conceived the idea and committed his design to paper for a magnetoelectrical device. In June of 1833, he had built his first magnetoelectrical machine capable of producing painful sparks and shocks to his tongue. In June, 1833, he demonstrated before the British Association for the Advancement of Science in Cambridge, the workings of his magnetoelectric machine, capable of decomposing water and of producing brilliant electrical sparks and steady light by bringing charcoal points near together.

He then improved on this version of his magnetoelectrical machine by using a strong horseshoe magnet mounted horizontally with three fixed coils to a shaft rotating around a horizontal axis. Like Pixii, Saxton turned the shaft of his machine by a handle attached to a wheel. His machine was the first rotating coil machine to generate electricity of alternating current. By 1835, he had redesigned and built a magnetoelectrical machine that produced unidirectional (galvanic) pulsed current, strong shocks, and decomposed water.

During his residence in England Saxton invented a locomotive differential pulley, an apparatus for measuring the velocity of vessels; an air-gun with metallic cartridge; an apparatus for obtaining an electrical spark from the magnetism of the earth; another for measuring the velocity of electricity, and several useful articles. He also invented an automatic machine for measuring the height of the tides; he patented an ever-pointed pencil. He perfected the medal-ruling machine, invented by Gobercht of the U.S. mint.

Vernier calipers probably made by Joseph Saxton, ca. 1843-1873

Joseph Saxton was tendered the office of director of the printing machinery of the Bank of England, but declined this place in order to accept, in 1837, that of constructor and curator of the standard weighing apparatus of the United States mint in Philadelphia.

During his connection with the mint he constructed the large standard balances that are used in the annual inspection of the assays and the verification of standard weights. In 1843 he was given charge of the construction of the standard balances, weights, and measures to be presented to each of the states for insuring uniformity of measures in all parts of the country under the auspices of the Office of Weight and Measures (OWM) for United States coast survey (now the National Bureau of Standards). He invented an automatic instrument for recording the height of the tides, and applied the reflecting pyrometer that had been previously invented to the construction of measuring rods that would retain their length while subjected to different temperatures. A deep-sea thermometer and an immersed hydrometer were among his later inventions.

This instrument was built at the Office of Weights and Measures (OWM) from Joseph Saxton’s design. It was probably used first for comparing the yard end-standard that was part of the standard yard apparatus distributed by OWM to the states and custom-houses and, after 1866, for comparing meter end-standards. Saxton’s comparator could measure differences of 1 micrometer (1 millionth of a meter). It used a sensitive indicating mechanism, which was based on the rotation of a small mirror, to detect differences between the standard and the measuring rod being calibrated.

The mirror was mounted on a shaft which was coupled to a spring-loaded slide that rested against the end of the standard. Very small differences in rod length caused the mirror to rotate a small amount. These small rotations of the mirror were greatly amplified by sighting through a telescope where the image of a graduated scale was reflected into the telescope by the mirror. The instrument was used by first adjusting the rotating mirror so that the scale read zero when the standard was in place and then reading the difference, in micrometers, when the rod to be measured was replaced by the standard.

This dividing engine was built at the Office of Weights and Measures (OWM) from the design of Joseph Saxton. It was probably used to divide the two scales of the matrix that was part of the standard yard apparatus distributed by OWM to the states and custom-houses. This apparatus consisted of a brass yard end-standard, which fit between the jaws of a matrix consisting of two scales: a scale of 3 feet, with the first foot divided into inches and the first inch divided into tenths of an inch and a scale of tenths of a yard with the first tenth divided into hundredths of a yard.

Drawing of Standard Yard Distributed to States by Saxton.

Joseph Saxton made very early photos (daguerreotypes) in the U.S.A. The earliest surviving American daguerreotype is probably a view of Central High School in Philadelphia from the window of the US Mint in what is now Penn Square, taken by Joseph Saxton; sometimes dated September 25, 1839.

He was married in 1850 to Mary H. Abercrombie of Philadelphia, Pa.

Christian Schussele’s Men of Progress was described in 1862 as a painting of “the most distinguished inventors of this country, whose improvements … have changed the aspect of modern society, and caused the present age to be designated as an age of progress.” The nineteen men in the painting were brought together only in the artist’s imagination. They are (left to right): Dr. William Thomas Green Morton (surgical anesthesia), James Bogardus (cast-iron construction), Samuel Colt (revolving pistol), Cyrus Hall McCormick (mechanical reaper), Joseph Saxton (5th from left) (magnetoelectrical machines), Charles Goodyear (vulcanization of rubber), Peter Cooper (railway locomotive), Jordan Lawrence Mott (railway locomotive), Joseph Henry (electromagnet design), Eliphalet Nott (efficient heat conduction for stoves and steam engines), John Ericsson (armored turret warship), Frederick Sickels (steam-engine gear and steering device for ships), Samuel Finley Breese Morse (electric telegraph), Henry Burden (horseshoe manufacturing machine), Richard March Hoe (rotary press), Erastus Bigelow (power loom for carpets), Isaiah Jennings (threshing machine, repeating gun, friction match), Thomas Blanchard (irregular turning lathe), and Elias Howe (sewing machine). In the background appears a portrait of Benjamin Franklin, the patron saint of American science and invention.

Saxton made and patented many inventions during his life. Mr. Saxton received from the Franklin institute in 1834 the Scott legacy medal for his reflecting pyrometer. He was awarded a gold medal at the Crystal Palace fair, London, in 1851, for a nearly precise balance. In 1837 he was elected a member of the American philosophical society, mid in 1863 became a charter member of the National academy of sciences. A sketch of his life was contributed by Joseph Henry to the first volume of the “Biographical Memoirs” of the latter body (Washington, 1877).

He died in Washington, D.C., Oct. 26, 1873.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Nicholas Joseph Callan

Nicholas Joseph Callan, Irish priest, scientist, and inventor, was a pioneer in the development of electrical science; inventor of the induction coil, which led to the modern transformer. He constructed a giant battery of 577 cells, producing enormous currents of electricity, to the delight, astonishment and danger of his students. Like Cavendish before him, he made an independent discovery of Ohm’s Law.

In applied science he devised several types of galvanic battery and influenced the study of high-voltage electricity. He also constructed one of the first DC electro-motors and wrote a patent on the protection of iron from rusting. Unfortunately, his name was forgotten and his inventions were attributed to other scientists. Nicholas Joseph Callan was born on December 22, 1799, the fifth child in a family of six or seven, at Darver, between Drogheda and Dundalk, Ireland.

His initial education was at an academy in Dundalk, run by a Presbyterian clergyman, William Nelson. His local parish priest, Father Andrew Levins, took him in hand as an altar boy and Mass server, and saw him start the priesthood at Navan seminary. He entered St Patrick’s College Maynooth (near Dublin, Ireland) in 1816. In his third year at Maynooth, Callan studied natural and experimental philosophy under Dr. Cornelius Denvir, who was later to become Bishop of Down and Connor.

Denvir introduced the experimental method into his teaching, and had an interest in electricity and magnetism. After ordination as priest in 1823, Callan went to Rome, where he studied at the Sapienza University, obtaining a doctorate in divinity in 1826. While in Rome he became acquainted with the work which had been carried out by Luigi Galvani (1737-1798), and by Alessandro Volta (1745-1827), pioneers in the study of electricity. On the resignation of Dr. Denvir, Callan was appointed to the chair of natural philosophy in Maynooth in 1826, and he remained in that post until his death in 1864.

During his life in Maynooth, with funding from friends and family, Callan began working with electricity. Electricity was still something of a toy, but he realised that with powerful batteries it could be put to practical and commercial use. The small priest must have seemed like an Irish Frankenstein – experimenting with electricity in his basement laboratory at Maynooth college, dishing out almighty electric shocks to unsuspecting volunteers, and electrocuting turkeys. Yet Reverend Nicholas Callan was one of Ireland’s great inventors. He invented the induction coil, built the most powerful batteries and electromagnets of his time.

Callan’s major claim to fame is as the inventor of the induction coil. Callan was influenced by the work of his friend William Sturgeon (1783-1850) who in 1825 invented the first electromagnet, and by the work of Michael Faraday and Joseph Henry with the induction coil. Working since 1834 on the idea of the induction coil, Callan developed his first induction coil in 1836.

He took a horseshoe shaped iron bar and wound it with thin insulated wire and then wound thick insulated wire over the windings of the thinner wire. He discovered that, when a current sent by battery through a “primary” coil (a small number of turns of thick copper wire around a soft-iron core) was interrupted, a high voltage current was produced in an unconnected “secondary” coil (a large number of turns of fine wire). Callan’s autotransformer was similar to that of Page’s except that he used wires of different sizes in the windings.

Callan’s induction coil also used an interrupter that consisted of a rocking wire that repeatedly dipped into a small cup of mercury (similar to Page). Because of the action of the interrupter, which could make and break the current going into the coil, he called his device the “repeater.”

Actually, this device was the world’s first transformer. Callan had induced a high voltage in the second wire, starting with a low voltage in the adjacent first wire. And the faster he interrupted the current, the bigger the spark. In 1837 he produced his giant induction machine: using a mechanism from a clock to interrupt the current 20 times a second, it generated 15-inch sparks, an estimated 600,000 volts and the largest artificial bolt of electricity then seen.

At the left is the device which Callan built to make and break the primary circuit of the coil. He called it a Repeater, a usage not followed later in the century.

Callan redesigned his induction coil in 1837 by separating the coils and making only the secondary coil deliver electrical shocks. Callan sent one of his induction coils to Sturgeon in 1837 who then exhibited it at the meeting of the Electrical Society of London in August 1837. Sturgeon then built his own autotransformer but wound thick copper wire as a primary coil. He next wound thin wire as a secondary coil over a wooden core (bobbin), and then connected the two coils by wire. In building his coil Sturgeon in 1837 introduced a manual interrupter to control the current.

The induction coil added a sense of theatre to a great many nineteenth century scientific laboratories, not as a prop but as a principal performer. For example, without the induction coil neither radio waves, x-rays, nor the electron would have been discovered and exploited as they were. The first induction coils were developed by a now forgotten Natural Philosopher, Nicholas Callan of St. Patrick’s College in Maynooth, Eire. Some impressive remains of his ventures can still be seen in Maynooth. Ruhmkorff received the pioneering credit for later work.

In view of the great importance of Callan’s invention of the induction coil, one might wonder why he was forgotten, and his invention attributed to a German-born Parisian instrument maker, Heinrich Ruhmkorff (1803-1877). The answer is simple. Maynooth was a theological university where science was the Cinderella of the Curricula. Callan’s colleagues often told him that he was wasting his time. In such an atmosphere Callan’s pioneering work was simply forgotten after his death. Like all instrument makers, Ruhmkorff put his name on every instrument he made.

“Ruhmkorff Coil” got into the textbooks. It was never challenged until Professor McLaughlin published his researches on Callan’s publications in 1936, which incontrovertibly proved that the inventor of the induction coil was Nicholas Callan of Maynooth. The first acknowledgement of Callan as its inventor was in the 1953 edition of Gregory and Hadley’s Textbook of Physics, revised by George Lodge, Senior Science Master at St. Columba’s College, Rathfarnham.

In 1838 this intrepid priest stumbled on the principle of the self-exciting dynamo. Simply by moving his electromagnet in Earth’s magnetic field, he found he could produce electricity without a battery. In his words, he found that “by moving with the hand some of the electromagnets, sparks are obtained from the wires coiled around them, even when the engine is no way connected to the voltaic battery”. The effect was feeble so he never pursued it, and the discovery is generally credited to Werner Siemens in 1866.

With the need to produce reliable batteries for his researches in electromagnetism, Callan carried out important work in this area, inventing the “Maynooth” battery in 1854, and a single fluid cell in 1855. Previous batteries had used expensive platinum, or unsatisfactory carbon, for one of their plates, and zinc for the other. Callan found that he could use inexpensive cast-iron instead of platinum or carbon. In the Maynooth battery, the outer casing was of suitably treated cast iron, and the zinc plate was immersed in a porous pot in the centre.

This required two different fluids, on the inside and outside of the porous pot. But he found also that he could make a simple and useful battery by dispensing with the porous pot and the two fluids, using a single solution. Callan would connect large numbers of these battery cells, and once joined 577 together, using 30 gallons of acid, to make what was then the world’s largest battery. Since there were no instruments yet to measure current or voltage, Callan assessed his batteries by the weight they could lift when connected to an electromagnet. His best effort lifted two tons. When Callan reported it in the Annals of Electricity, a London professor came over to witness the spectacle, and was said to be incredulous.

Callan’s ingenuity knew no bounds and in 1853 he patented an early form of galvanisation using a lead-tin mix to protect iron from rusting, something he discovered when he was experimenting with various battery designs. His 1853 patent document, complete with an enormous royal seal from Queen Victoria, is displayed at Maynooth’s new museum.

He also constructed electric motors. Callan probably also had one of the world’s first electric vehicles, because in 1837 he was using a primitive electric motor to drive a small trolley around his lab. He even proposed using batteries instead of steam locomotives on the new-fangled railways. Callan later realised his batteries were not powerful enough, and indeed, it took another hundred years before battery-powered trains invented by another Irishman, James Drumm, were used on Dublin railways. With great foresight he also predicted electric lighting, at a time when oil was still widely used and gas was the next new thing.

He was a contemporary of Charles Parsons’ father, the Third Earl of Rosse, who had a position on the Board of Visitors to Maynooth College. A student yarn relates how Callan called to Birr to see the telescopes, but for some reason was not admitted.

When the Third Earl later visited Maynooth to see the induction coil, Callan sent his respects, but suggested that the noble lord should return to Birr to view the coil through his giant telescope! He was an eccentric character who was said to have used his students in his experiments to test the strength of electric voltage. Fortunately, there were no fatalities but he did manage to render a future Archbishop of Dublin unconscious. After this mishap he experimented with chickens. Maynooth College has a museum dedicated to the work and life of this priest scientist.

Nicholas Callan was a notable writer and translator of theological and ascetical works, he wrote about twenty religious books, one of which influenced the conversion of Newman. Nicholas Callan, holy priest and scientist died from natural causes at Maynooth on January 10th 1864.

As part of the Millenium celebrations An Post launched the ‘Discovery’ series of stamps to celebrate major scientific achievements in the second millenium. Included in the series is a stamp commemorating Reverend Nicholas Callan. Others featured in the series include Gallileo, Einstein, Marie Curie, and Thomas Edison.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Joseph Henry

Joseph Henry, the leading American scientist after Benjamin Franklin until Willard Gibbs, was a professor at Princeton from 1832 to 1846. His chief scientific contributions were in the field of electromagnetism, where he discovered the phenomenon of self-inductance.

The unit of inductance, called “the henry”, immortalizes his name. Henry is also remembered as the first Secretary of the Smithsonian Institution, where he made extraordinary contributions to the organization and development of American science.

Joseph Henry was born to Scottish immigrants in Albany, New York in the 1799. Henry’s father,William Henry (1764-1811), a day-labore, died when Joseph was eight and financial circumstances forced his mother, Ann Alexander Henry (1760-1835), to send Henry to live with his grandmother in Galway, New York, a village about 40 miles from Albany. There he worked in a general store after school hours and at the age of thirteen was apprenticed to a watchmaker.

As a young man he became interested in the theater and was offered employment as a professional actor, but in 1819 several well-positioned Albany friends persuaded him instead to attend the Albany Academy, where free tuition was provided. At fourteen he moved back to Albany to work a day job and attend night school at the Albany Academy, a boys’ school. His friends there considered him an actor, playwright, showman and orator. Slowly, however, his interests shifted and he began reading textbooks on mathematics, philosophy, astronomy and chemistry, most of which were authored by English scientists and philosophers. He read novels after gaining access to the church library through a hole in the floor. The book that most impressed him in life, however, was not fiction but George Gregory’s Popular Lectures on Experimental Philosophy, Astronomy, and Chemistry. Years later, giving a copy of the book to his only son, Henry wrote on the fly-leaf, “This… opened to me a new world of thought and enjoyment; fixed my attention upon the study of nature, and caused me to resolve at the time of reading it that I would immediately devote myself to the acquisition of knowledge.” Henry found himself in the awkward position of having access to the understandings developed by the world’s top researchers, but lacking the materials to recreate or further their experiments. However, as Henry’s career progressed, these limitations would spur him to make new discoveries.

He supported himself for a time as a kind of circuit-riding grammarian and schoolteacher, earning $8 a week by tutoring the children of well-to-do families. He taught the elder Henry James, religious writer and the father of William James, the philosopher, and Henry James, the novelist. Henry’s early career also included surveying. One summer, he headed a party assigned to establish the route of the proposed Great Road in New York State. Ironically, he was denied an appointment with the Corps of Topographical Engineers of the United States Army, a unit that would someday well serve the purposes of his Smithsonian.

Stained glass window in Albany’s First Presbyterian Church memoralizing site of Joseph Henry’s baptism. The window’s ennobling iconography – a beatific Henry instructing twelve disciples at the Albany Academy – is reinforced by captions at bottom of left and right panels: Master Scientist and Devout Christian. First Presbyterian Church.

After graduating from Albany Academy, Henry spent several years working as a district schoolteacher and as a private tutor, then a canal surveyor, and eventually as an engineer for canal construction. In 1826, when Albany Academy offered him the chair of Mathematics and Natural Philosophy, he accepted without question.

Here, in spite of a teaching schedule that occupied him seven hours a day, he did his most important scientific experiments. Henry had become interested in terrestrial magnetism, which was then, as today, an important scientific topic. This led him to experiment with electromagnetism. His apprenticeship as a watchmaker stood him in good stead in the construction of batteries and other apparatus.

Shortly before he began his new position at the academy Henry went to New York, where he first saw an electromagnet made by William Sturgeon. Back at Albany Academy, Henry wanted to build his own magnet but his lecture schedule and a lack of laboratory equipment made it impossible. Experimental work had to wait until summer vacations, and then could be performed only on a very limited budget.

In this regard, the single greatest limitation for Henry was the large, expensive galvanic batteries needed for the electrical experiments. The batteries required large zinc and copper plates, which were rare and very costly, especially in a city as remote as Albany. Working with a much smaller battery than his European counterparts, Henry insulated the copper wire with silk ribbon and wound 540 feet in nine coils of 60 feet each. He then let the current run through the various lengths of wire and recorded the amount of weight the battery could hold.

Shortly before he began his new position at the academy Henry went to New York, where he first saw an electromagnet made by William Sturgeon. Back at Albany Academy, Henry wanted to build his own magnet but his lecture schedule and a lack of laboratory equipment made it impossible.

Experimental work had to wait until summer vacations, and then could be performed only on a very limited budget. In this regard, the single greatest limitation for Henry was the large, expensive galvanic batteries needed for the electrical experiments. The batteries required large zinc and copper plates, which were rare and very costly, especially in a city as remote as Albany. Working with a much smaller battery than his European counterparts, Henry insulated the copper wire with silk ribbon and wound 540 feet in nine coils of 60 feet each. He then let the current run through the various lengths of wire and recorded the amount of weight the battery could hold.

Before he left Albany, he built one for Yale that would lift 2,300 pounds, the largest in the world at that time. In experimenting with such magnets, Henry observed the large spark that was generated when the circuit was broken, and he deduced the property known as self-inductance, the inertial characteristic of an electric circuit. The self-inductance of a circuit tends to prevent the current from changing; if a current is flowing, self-inductance tends to keep it flowing, or if an electromotive force is applied self-inductance tends to keep it from building up. Henry found that the self-inductance is greatly affected by the configuration of the circuit, especially the coiling of the wire. He also discovered how to make non-inductive windings by folding the wire back on itself. While Henry was doing these experiments, Michael Faraday did similar work in England. Henry was always slow in publishing his results, and he was unaware of Faraday’s work. Today Faraday is recognized as the discoverer of mutual inductance (the basis of transformers), while Henry is credited with the discovery of self-inductance.

This picture shows some of Henry’s experimental apparatus, including magnets, a battery, relay switches, and insulated coils.

In the summer of 1831 Henry described the first of these applications in a short paper, “On a Reciprocating Motion Produced by Magnetic Attraction and Repulsion.” It was a simple device whose moving part was a straight electromagnet rocking on a horizontal axis. Its polarity was reversed automatically by its motion as two pairs of wires projecting from its ends made connections alternately with two electrochemical cells. Two vertical permanent magnets alternately attracted and repelled the ends of the electromagnet, making it rock back and forth at 75 vibrations per minute.

Henry at this time considered his little machine merely a “philosophical toy,” but nevertheless believed it was important as the first demonstration of continuous motion produced by magnetic attraction and repulsion. Furthermore, “in the progress of discovery and invention, it is not impossible that the same principle, or some modification of it on a more extended scale, may hereafter be applied to some useful purpose.” Indeed, one authority has stated, “Henry’s apparatus was the first clear-cut instance of a motor capable of further mechanical development. It had the essentials of a modern DC motor: a magnet to provide the field, an electromagnet as armature, and a commutator to apply the mechanical forces at the right time.” Other inventors did later develop motors of various designs based on similar reciprocating actions, but it is not clear whether these inventors knew of Henry’s device, or created theirs independently. In any case, reciprocating motors never became commercially successful; continuous rotary motion proved to be a more efficient and useful principle.

Today, the commercial applications for Henry’s electromagnetic experiments seem obvious. Eventually, inventors would use the electro-magnet as the basis for the telegraph, the electric motor, and the dynamo. Henry claimed that he did not pursue practical applications for the electro-magnet because:

“I freely renounced all right to the invention as I consider the machine in the present state of the science a philosophical toy.”

Later in his life, when asked why he didn’t patent the electromagnet, Henry replied:

“I did not then consider it compatible with the dignity of science to confine the benefits which might be derived from it to the exclusive use of any individual.”

These claims have long been heralded by biographers as the mantra of a “pure scientist.” However, more recent biographies have pointed out that Henry had actively pursued a relationship with entrepreneurs regarding a way to use the electro-magnet to extract iron from crushed ore. As Albert Moyer pointed out, “To be sure, [Henry] did not share the common belief that natural philosophy was above payment and patents.”

JOSEPH HENRY Educator

In 1832, when Henry was 35, Yale’s distinguished geologist Benjamin Silliman was consulted regarding the possible appointment of Henry to Princeton. Silliman replied, “As a physical philosopher he has no superior in our country; certainly not among the young men.” Henry, always modest, had responded to tentative inquiries, “Are you aware of the fact that I am not a graduate of any college and that I am principally self-educated?”

In the early 1830s Princeton University offered Henry the chair of natural philosophy, which Henry accepted. The Princeton professorship offered a much lighter teaching assignment and a slightly better financial arrangement than he had in Albany, plus the prestige of one of America’s premier universities. For over 15 years, Henry continued to pursue research in natural philosophy at Princeton.

Henry was both a leading researcher and an experienced teacher, having taught at the Albany Academy in New York for six years and at the College of New Jersey (now Princeton University) for almost 14 years. About half of the 1,000 or so students taught by Henry became doctors, lawyers, ministers, college professors, or senior government officials. Among the rest were businessmen, teachers, and mid-level government workers.

Henry’s initial salary at Princeton was $1,000 per annum plus a house. The Trustees also provided $100 for the purchase of a new electrical machine. At that point the College was near bankruptcy and Maclean was trying to institute reforms and build up the faculty. Henry was a notable acquisition, and he found the lighter teaching schedule and the intellectual companionship at Princeton congenial, especially when his brother-in-law Stephen Alexander joined the faculty to teach astronomy.

Henry worked with Alexander in the observation of sunspots and continued his own work on magnets, building for Princeton an even larger magnet than he had built for Yale, one that would lift 3,500 pounds. He also rigged two long wires, one in front of Nassau Hall and one behind, so that he was able to send a signal by induction through the building. Another wire from his laboratory in Philosophical Hall to his home on the campus was used to send signals to his wife; this signal system used a remote electromagnet to close a switch for a stronger local circuit, and constituted in effect the invention of the magnetic relay.

A similar arrangement was used by S.F.B. Morse in the invention of the telegraph; Morse had consulted Henry and had used one of his scientific papers. Later, Henry was called to testify in a patent suit involving the telegraph, Morse vs. O’Reilly. Although Henry had encouraged and helped Morse in his project, his testimony that the principle of the telegraph had been known to himself and to Professor Wheatstone in England undermined Morse’s claim to originality. This led to much unpleasantness and controversy, but Henry’s reputation emerged unscathed.

In addition to natural philosophy (physics), Henry taught chemistry, geology, mineralogy, astronomy, and architecture — in the words of Frederick Seitz, Ph.D. ’34, former president of the National Academy of Sciences, he was “a very large economy package.” A rather reserved and quiet man, he was nevertheless a popular teacher. The College gave Henry an opportunity, then unusual, to travel abroad on leave at full salary. In 1837 he met Faraday, Wheatstone, and other British scientists, to whom he explained his idea of “quantity” and “intensity” circuits (low and high impedance, in modern terms). He returned to Princeton with a variety of scientific equipment purchased abroad.

By all accounts, whether in contemporary letters and diaries or in later reminiscences, Henry was an outstanding teacher, beloved and respected by his students for his knowledge, sense of humor, and willingness to discuss issues outside the curriculum. A former student wrote to Henry: “Until I came under your direction I cannot recollect of ever having possessed an idea– This is no exaggeration, but my serious opinion – I mean that I had never once thought for myself on any one subject.

” Henry had, in the words of Asa Gray, a botanist at Harvard and Henry’s contemporary, “a genius for education.” Henry often said he did not want to teach his students “the mere facts of natural philosophy.” What he wanted his students to take away with them when they graduated was a way of thinking and learning that would be applicable in the wider world. They had to be able to distinguish between mere knowledge – “the acquiantance [sic] with facts” – and wisdom, which was “the application of principles.”

“A knowledge of general principles gives a man an immense advantage over his less perfectly educated neighbour or competitor,” Henry asserted. He reminded his students this was true in “Theology Law or Medicine or in any subject to which you may turn your attention.”

Reflecting on his own experience in integrating research and teaching, Henry insisted that the best college professors were researchers. He argued that when selecting professors, a college should give “the preference to a person who has made some advance in the way of original research.” Henry was well aware of the shortage of researchers in the United States around 1846. By supporting research, the Smithsonian was also upgrading the quality of college science teaching.

Henry supported educational reform in other ways. He served as first president of the Columbian Association of Teachers, which was organized at the Smithsonian in December 1849 at his suggestion. This local society aimed “to elevate the character of [the teaching] profession, and secure…that rank in society to which…[teachers] were entitled.”

Henry was elected first vice president of the Friends of Public Education in 1850. Two years later, he was elected president of the American Association for the Advancement of Education, which was a successor to the Friends of Public Education. The association mainly appealed to public school administrators, who were interested in such questions as school districting, school architecture, teacher qualifications, grade levels, methods of instruction, and taxation policies. The overt purpose of the association, a precursor of the National Education Association, was to formulate national standards for public education.

Henry took advantage of the forums provided by this national education reform movement to argue for the importance of using researchers as educators. In 1854, in addressing the annual meeting of the American Association for the Advancement of Education, he argued that researchers made the best textbook writers, whatever the level of instruction:

But few persons can devote themselves so exclusively to abstract science as fully to master its higher generalizations, and it is only such persons who are properly qualified to prepare the necessary books for the instruction of the many. I cannot for a moment subscribe to the opinion which is sometimes advanced that superficial men are best calculated to prepare popular works on any branch of knowledge.

It is true that some persons have apparently the art of simplifying scientific principles; but in the great majority of cases this simplification consists in omitting all that is difficult of comprehension. There is no task more responsible than that of the preparation of an elementary book for the instruction of the community. Henry went on to assert that “it should be our object to bring more into repute profound learning and to counteract the tendency to the exclusive diffusion of popular and mere superficial knowledge.”

In Henry’s world view, support of basic research resulted in superior teaching, superior textbooks, and superior popular expositions of science. In turn, this served to better equip young men and women to pursue their life’s work, whether in law, medicine, the ministry, or any other field of endeavor. Henry believed that by serving the research community, the Smithsonian served a larger public.

The scene at left is from a mural painted by Gifford Beal (Princeton class of 1900) in 1946, for the bicentennial of Princeton’s founding. The mural, located in the lobby of the John C. Green School of Engineering, depicts Henry demonstrating electrical phenomena. The backdrop is Princeton’s Philosophical Hall, where Henry taught and performed many electrical experiments, including telegraphic ones.

During his remaining years in Princeton Henry continued his electrical investigations, but also branched out into the study of phosphorescence, sound, capillary action, and ballistics. In 1844 he was a member of a committee to investigate the explosion of a gun during a demonstration on the new U.S.S. Princeton; the Secretaries of State and Navy and several congressmen were among the spectators killed. His experiments on gun castings on this committee led him into the subject of the molecular cohesion of matter.

Joseph Henry was important to the history of the telegraph in two ways. First, he was responsible for major discoveries in electromagnetism, most significantly the means of constructing electromagnets that were powerful enough to transform electrical energy into useful mechanical work at a distance. Much of Morse’s telegraph did indeed rest upon Henry’s discovery of the principles underlying the operation of such electromagnets. Secondly, Henry became an unwilling participant in the protracted litigation over the scope and validity of Morse’s patents.

Between 1849 and 1852 the defendants in three infringement suits subpoenaed Henry in the hopes that his statements would weaken or invalidate Morse’s claims, and his testimony proved crucial to the Supreme Court’s 1854 split decision that struck down Morse’s broadest claim.4 Because of Henry’s involvement in these suits, the two men engaged in a bitter dispute over issues of scientific and technological priority, a conflict that continued until their deaths in the 1870s. As petty and mean-spirited as this conflict was, it nevertheless revealed much about their differing attitudes concerning the relative importance of the work of scientists and inventors in the middle third of the nineteenth century.

The first Smithsonian Secretary

In 1846, having received from an Englishman, James Smithson, a large bequest for the founding of an institution “for the increase and diffusion of knowledge among men,” the U.S. Congress established the Smithsonian Institution. A distinguished board was appointed, with instructions to find the best possible man to head the new Institution as secretary, and the invitation was soon extended to Henry. He was reluctant to leave Princeton and the opportunity to do his own scientific investigations.

“If I go,” he said to a friend, “I shall probably exchange permanent fame for transient reputation.” But he finally accepted and threw his enormous energy and knowledge and experience into the development of the Smithsonian, which became the first great driving force in the organization and direction of American science.

When Joseph Henry accepted the position as Secretary of the Smithsonian on December 7, 1846, he was the foremost experimental physicist in the United States. The responsibilities of his new post, however, would require a great personal sacrifice. Never again would Henry have enough time to pursue his own research agenda.

Although Henry never ceased thinking of himself as a research scientist and educator, after becoming Secretary his chief roles were those of science administrator and adviser to presidents, vice presidents, cabinet secretaries, and members of Congress on all aspects of science and technology. When Henry entered the laboratory, he no longer pursued basic research or followed up a random observation that struck his curiosity. As a member of various government boards and commissions, Henry now devoted himself to applied research.

As an adviser, Henry had tremendous influence. His correspondence demonstrates that the careers of individual scientists, the livelihoods of inventors, and the future of certain government scientific activities came to depend in part upon his support and his ability to sway members of Congress or cabinet members. Such was his reputation that, according to Henry, one secretary of the interior assured him that “if the request was . . . backed by myself that would be sufficient!”

The nation came to depend on his expertise in a number of areas. For the United States Capitol Building, for example, he was called upon by the vice-president and various cabinet secretaries to provide advice on the vulnerability of the Capitol dome to lightning; to evaluate the plans of Montgomery C. Meigs for the acoustics, heating, and ventilation of the new chamber of the House of Representatives; and to test samples of marble for the Capitol extension.

Henry devoted even more time to the country’s system of lighthouses. In 1852, he was appointed by President Millard Fillmore as one of the six members of the United States Light-House Board. Henry remained on the board for the next twenty-five years, serving as chairman for the last six years of his life. Thus, he had a role in the oversight of a government science-technology activity with an annual budget of more than $500,000 in 1852, or sixteen times the Smithsonian annual budget at the time.

The United States Light-House Board was responsible for the construction and repair of lighthouses; the establishment of procedures; and the procurement of personnel, supplies, and equipment. Henry took charge of its experimental and testing activities. After his death it was estimated that, in addition to attending board meetings, he generally spent from six to eight weeks each year working full-time for the board during his vacations from the Smithsonian. He helped make the board into a center for applied research in optics, thermodynamics, and acoustics.

Henry served the nation in another capacity during the Civil War. Inventors overwhelmed the government with suggestions for various kinds of military technology at a time when there was no mechanism for screening and evaluating the proposals. Henry, to whom the military referred many of these, suggested the establishment of what became known as the Permanent Commission of the Navy Department.

Henry served on the three-member commission from its inception in early 1863, and the group met as often as three times a week, often in the Castle, to evaluate a steady stream of proposals for warship designs, underwater guns, torpedoes, and the like. Henry wrote former President Fillmore after the war that the commission saved the government “from rushing into many schemes which, under the guise of patriotism, were intended to advance individual interest.”

The National Academy of Sciences was also established in the spring of 1863 to offer scientific advice to the government. Henry was one of its fifty incorporators. When his dear friend and first president of the academy, Alexander Dallas Bache, died in 1867, Henry, who had been acting president of the academy during Bache’s illness, agreed to serve as president. Until his death in 1878, he was concurrently Secretary of the Smithsonian Institution and president of the National Academy of Sciences, as was Charles Doolittle Walcott, the Smithsonian’s fourth Secretary, some fifty years later.

Father of Weather Service

Joseph Henry helped shape the world we know when he laid the foundation of a national weather service shortly after becoming the Smithsonian’s first Secretary.

Henry’s interest in meteorology dated to his days as a professor at the Albany Academy in Albany, New York, where he compiled reports of statewide meteorological observations for the University of the State of New York. As a professor of natural philosophy (physics) at the College of New Jersey (Princeton), he conducted research on lightning and engaged in discussions with pioneer meteorologists both in the United States and Britain about storm patterns and atmospheric physics.

When Henry came to the Smithsonian, one of his first priorities was to set up a meteorological program. In 1847, while outlining his plan for the new institution, Henry called for “a system of extended meteorological observations for solving the problem of American storms.” By 1849, he had budgeted $1,000 for the Smithsonian meteorological project and established a network of some 150 volunteer weather observers. A decade later, the project had more than 600 volunteer observers, including people in Canada, Mexico, Latin America, and the Caribbean. Its cost in 1860 was $4,400, or thirty percent of the Smithsonian’s research and publication budget.

The Smithsonian supplied volunteers with instructions, standardized forms, and, in some cases, with instruments. They submitted monthly reports that included several observations per day of temperature, barometric pressure, humidity, wind and cloud conditions, and precipitation amounts. They also were asked to comment on “casual phenomena,” such as thunderstorms, hurricanes, tornadoes, earthquakes, meteors, and auroras.

Enlisting enthusiastic volunteers proved less of a problem than interpreting their observations. In 1856, Henry contracted with James H. Coffin, a professor of mathematics and natural philosophy at Lafayette College in Easton, Pennsylvania, to carry out this task. Coffin, who received as many as half-a-million separate observations in a year, complained that some contained “new-coined characters & hieroglyphics” that made them unintelligible. He also had to employ up to fifteen human “computers” to help make the necessary arithmetical calculations. In 1861, he finally published the first of a two- volume compilation of climatic data and storm observations based on the volunteers’ reports for the years 1854 through 1859.

A second aspect of Henry’s meteorological project was weather telegraphy. Early on, Henry foresaw the storm-warning potential of the telegraph, an invention he had pioneered himself in the 1830s and that Samuel Morse had made commercially feasible by 1845. Realizing that storms in the United States generally moved from west to east, he wrote in the Smithsonian’s 1847 annual report that “the extended lines of telegraph will furnish a ready means of warning the more northern and eastern observers to be on the watch for the first appearance of an advancing storm.”

By 1849, Henry worked out an arrangement with a number of telegraph companies to allow free transmission of local weather data to the Smithsonian. He also proposed to supply “the most important stations” with barometers and thermometers. By 1857, telegraph stations from New Orleans to New York were cooperating.

These dispatches enabled Henry to devise a large daily weather map. Its purpose, Henry wrote, was “to show at one view the meteorological condition of the atmosphere over the whole country.”

The map, which Henry mounted in 1856 for public display in the Castle, was dotted with colored discs. As telegraph reports came in each morning, an assistant placed white discs in locations with fair weather, blue ones where snow fell, black where there was rain, and brown where conditions were cloudy. Arrows on the discs showed the direction of prevailing winds. The map became a popular attraction. Henry noted that tourists who viewed it “all appear to be specially interested in knowing the condition of weather to which their friends at home are subjected at the time.” He shared the telegraph dispatches with the Washington Evening Star, which, in May 1857, began publishing daily weather conditions at nearly twenty different cities. Henry thus helped give rise to the popular newspaper weather page. Henry’s map also made some forecasting possible. “If a black card is seen in the morning on the station at Cincinnati, indicating rain at that city,” he noted, “a rain storm may confidently be expected at Washington at about seven o’clock in the evening.” This rule-of-thumb proved reliable enough for Henry to postpone evening lectures at the Smithsonian on days Cincinnati had morning rain.

Henry apparently envisioned a system of storm warnings, announcing in his annual report for 1857 that he hoped the following year to arrange with telegraph lines “to give warning on the eastern coast of the approach of storms.” But he was not able to implement the plan before the Civil War engulfed the nation.

The war dealt a major blow to the meteorological project. Henry wrote in 1861 that the project “suffered more from the disturbed condition of the country than any other part of the operations of the Smithsonian establishment.” Urgent public business forced weather information off the telegraph lines, and secession cut Henry off from his southern observers. Although he was able to revive the project after the war, Henry began taking steps to transfer its operations to the federal government.

In his annual report for 1865, Henry called for the federal government to establish a national weather service capable of issuing storm warnings and other weather predictions. Others urged similar proposals, and in 1870 Congress passed a bill that put storm and weather predictions in the hands of the U.S. Army’s Signal Service. By 1874, Henry convinced the Signal Service to take over the volunteer observer system as well.

The weather functions of the Signal Service were transferred in 1891 to the newly established U.S. Weather Bureau, which later became the National Weather Service. That service today, as David Laskin puts it in his 1996 book Braving the Elements: The Stormy History of American Weather, “still adheres to the same fundamental structure and principles that Joseph Henry devised and set in motion.”

Henry’s motivations and morality

In his research on electricity and magnetism, Henry achieved and sustained the high respect of especially those American and foreign colleagues with whom he had close personal relationships. He never, however, progressed to the point of winning top recognition among more impersonal, elite segments of the broader, international scientific community.

Indeed, Henry’s published research record, although notable, was patchy. He often failed to report his findings promptly and in widely accessible outlets. Moreover, he often failed to grasp–or, at least, to report–the fuller import of his laboratory gleanings; his pattern was to focus undividedly on a line of investigation only after another researcher announced results involving a similar or identical line.

Unquestionably, in personal temperament Henry displayed a fervent commitment to duty, service, and self-sacrifice. In accepting the secretaryship of the Smithsonian in late 1846, for example, he downplayed the prestige of his new station and repudiated any implication of personal or even professional fulfillment. Instead, insisting that he had made no effort to obtain the post, he voiced an altruistic rationale for conceding to others’ calls to serve as Secretary. He had accepted, he maintained, out of duty to the nation and to science.

This high-minded rationale, with its connotation of self-sacrifice and moral obligation, contrasts sharply, however, with a set of baser issues that Henry repeatedly raised in his more intimate correspondence with friends and relatives–issues of salary and recognition.

He told his brother that he would not entertain the suggestion of moving from Princeton to Washington unless the salary were generous; he also said that, if award of the secretaryship were dependent on scientific reputation, then he was undoubtedly entitled to the situation. The rationale of dutifully acquiescing to the secretaryship also contrasted with Henry’s earlier hints to colleagues about his discontent with existing levels of reward and recognition as a Princeton professor. Nevertheless, he consistently cited duty, rather than self-fulfillment, as his motive for accepting the post.

As his letters and other writings clearly show, Henry believed the rationale–believed that he was selflessly fulfilling a moral obligation. For decades, he had been placing duty and altruism at the core of his personal value system. This stance was an expression of, however, not merely his innate temperament or American culture’s prevailing republican and Protestant values. The stance also had psychological shadings traceable to childhood traumas.

The traumas, which Henry kept hushed most of his adult life, arose from a tragedy in his working-class family: his father’s alcoholism and death due to delirium tremens. Henry emerged from a troubled youth with a deep need for approval and affirmation. But he masked public expressions of this egocentric side of his personality. Instead, he imposed on himself a regimen of service to others. Cloaking his personal desires, he consistently invoked what he perceived to be his moral duty as his motive for following a particular course of action–whether in professional or personal endeavors.

Henry’s years of service as science adviser, as much as his own pioneering research, make fitting the headline in the New York Times upon his death, “A Loss to All the Nation.”

At Henry’s memorial service, held in the Capitol on January 16, 1879, congressional Regent (and later President of the United States) James A. Garfield acknowledged that Henry’s move to Washington, D.C., was a loss to research. But he reminded his audience that “the Republic has the right to call on all her children for service. It was needful that the Government should have, here at its capital, a great, luminous-minded, pure-hearted man, to serve as its counselor and friend in matters of science.”

Things named after Henry to honor and to remember him

Over the years, people have honored Joseph Henry by naming a variety of things after him, including a laboratory, a professorial chair, ships, and even a mountain range. Note that the naming began during Henry’s own lifetime.

After hearing of Henry’s death in May 1878, William Barber, engraver of the U.S. mint, offered to design this medal in honor of Henry. He and his son Charles completed the design the following year and donated the medal to the Smithsonian Institution for “any application that might…be afterwards suggested.” Henry’s birth date is mistakenly given as 1799, rather than 1797, due to confusion over Henry’s age. On the back of the medal is a Latin inscription taken from the Odes of Horace, Book 1, Ode 24: “Incorrupta Fides Nudaque Veritas Quando Ullum Inveniet Parem.” The lines from which this inscription is excerpted read, according to one modern translation, “Where then will Justice, and Faith, the sister of Justice, and Decency, and Truth that needs no ornament, find his equal?” In January 1967, the Smithsonian’s Board of Regents proposed to use the Henry medal to recognize distinguished service to the institution.

Since that time, recipients of the medal have included a Smithsonian secretary, Charles Abbot, an astrophysicist, Fred Whipple, an anthropologist, T. Dale Stewart, and a U.S. vice-president and Smithsonian regent, Hubert H. Humphrey. In 1997, on the occasion of the bicentennial of Henry’s birth, the medal was awarded to physicist Frederick Seitz, a long-time supporter of the Henry Papers Project and chair of its advisory committee.

In August 1893, an International Congress of Electricians met in Chicago during the World’s Columbian Exposition. Scientists and engineers at the congress adopted names and agreed on definitions for eight units of electrical measure: the ohm, the ampere, the volt, the coulomb, the farad, the joule, the watt, and the henry. The motion to adopt the henry, the only unit named after an American, came from the leader of the French delegation, physicist Eleuthere Elie Nicolas Mascart. The henry was defined as “the induction in a circuit when the electro-motive force induced in this circuit is one international volt, while the inducing current varies at the rate of one ampere per second.”

In 1872, John C. Green, founder of the School of Science at Princeton, endowed a chair of physics in Henry’s honor (held since then by C. F. Brackett, W. F. Magie, E. P. Adams, H. D. Smyth, and J. A. Wheeler).

Almost a century later, when the main physics building, Jadwin Hall, was dedicated in 1970, the Physics Department manifested its continuing esteem for Henry by declaring that all of the laboratory facilities housed in Jadwin and Palmer Halls and the Elementary Particles Laboratory should be collectively known as the Joseph Henry Laboratories. Some of Henry’s laboratory equipment is on display in the lobby of Jadwin Hall. His campus home, built to his design, is called the Joseph Henry House.

The statue of Joseph Henry in front of the Smithsonian Castle, Washington, D.C., was unveiled late on the sunny afternoon of April 19, 1883, five years after Henry’s death.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Johann Christian Poggendorff

Poggendorff studied problems in electricity and magnetism, he developed a mirror galvanometer and, actually, he gave the name “galvanometer” to a physical instrument measuring an electric current.

Poggendorff was German physicist and chemist. Professor of chemistry at the University of Berlin from 1834, he investigated problems in electricity and magnetism.

In the same year (1826) as Nobili constructed his new galvanometer, Poggendorff invented a method of reading a galvanometer scale by means of a mirror – he designed a mirror galvanometer. Poggendorff built a system in which he installed a small flat mirror to reflect a relatively narrow beam of light.

This apparatus, with the aid of an eyeglass, can be used to measure the torsion angle of the wire suspended from the bar or magnetic needle, when it is under the influence of the electrical current of the conductor. Actually, Poggendorff invented name “galvanometer” for the instrument detecting an electric current to honour Galvani (1737-98) who in fact was unaware of the magnetic effect.

The design of a mirror galvanometer comprises a coil of wire wound on a soft iron core suspended in the magnetic field of a permanent magnet – this coil is suspended generally by means of a strip of phosphor bronze wire and located centrally between the poles of the permanent magnet. The coil will react to a coupling force the extent of which is proportional to the current flowing through the coil, and this will cause the coil to rotate. A small mirror is attached to the coil so that a beam of light reflected by this mirror will sweep through an angle which is proportional to the current passing through the coil.

He founded (1824) and edited the important “Annalen der Physik und Chemie” and edited the first two volumes (1863) of “Biographisch-literarisches Handworterbuch”.

In 1860, J. C. Poggendorf, the editor of a journal of physics and chemistry, received a monograph from Zollner describing his illusion. Poggendorff noticed and described another effect of the apparent misalignment of the diagonal lines in Zollner’s figure. Thus the Poggendorff illusion was discovered. The two segments of the diagonal line appear to be slightly offset in this figure. But it is a straight line !!!


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Samuel Finley Breese Morse

Samuel F. B. Morse was an artist by training and worked successfully as a portrait painter until the 1830s. Today, however, Morse is primarily remembered as the inventor of the electric telegraph and the related code system that bears his name. Samuel Finley Breese Morse, born in Charlestown, Mass., 27 April, 1791, was the oldest son of Reverend Jedidiah Morse and Elizabeth Ann (nee Breese) Morse. His dad, Jedidiah Morse, (1761-1826) was an American Congregational pastor and wrote a series of widely used geography textbooks. Since the age of four, Morse had been interested in drawing.

When he was four, Samuel etched his teacher’s face on a chest of drawers. At the age of eight Morse was taken to Phillips Academy, where his father was a trustee. He was unhappy under their rule, and twice as homesick, so he fled back to Charleston. He entered Yale College at 1805 where he majored in chemistry and natural philosophy.

Portraits of Rev. Dr. and Mrs. Morse, painted by Savage in 1794, are in the possession of their grandson Gilbert Livingston Morse. The family of the late Richard Cary Morse own a portrait of his mother in candle-light, painted by her artist-son: and there is a portrait of Dr. Morse, in his later years, by the same hand. Jedidiah and Elizabeth Ann (Breese) Morse had eleven children, of whom, however, only three survived their infancy.

Information on Morse’s family is here.

National Museum of American History, Smithsonian Institution, Washington, D.C.

Samuel F. B. Morse’s watercolor depicts his father, Jedidiah Morse, at the center of his family, lecturing on geography. The setting includes a prominently displayed terrestrial globe and a book (probably meant to be one of Morse’s own), opened to show an extended diagram or map. Sidney and Richard Morse stand to their father’s left, while Samuel Morse leans forward on his right, intent on his father’s words and gestures. Elizabeth Breese Morse also listens closely, her sewing scissors discarded tiny implements overshadowed by the bulk and visual authority of the globe and lecturer.

In Yale Morse received his first instruction in electricity from Prof. Jeremiah Day, also attending the elder Silliman’s lectures on chemistry and galvanism. In 1809 he wrote: ” Mr. Day’s lectures are very interesting; they are upon electricity; he has given us some very fine experiments, the whole class, taking hold of hands, form the circuit of communication, and we all received the shock apparently at the same moment.

I never took an electric shock before; it felt as if some person had struck me a slight blow across the arms.” However, his college career was perhaps more strongly marked by his fondness for art than for science, and he employed his leisure time in painting. One day, he wrote a letter to his parents from his college saying that he was made to be a painter. He wrote: “My price is five dollars for a miniature on ivory, and I have engaged three or four at that price. My price for profiles is one dollar, and everybody is willing to engage me at that price.”

Mr. and Mrs. Morse were afraid that he couldn’t make a living as a painter, so they made him be a bookseller, when he was released from his college duties in 1810. He worked as a bookseller but at night he would paint. He had no profession in view, but to be a painter was his ambition. Finally his parents realized how he loved art so they found the money for Morse to study art.

Morse moved to Boston and became the private pupil and friend of Washington Allston, who introduced him to a traditional program of academic study that encompassed drawing, anatomy, and art theory. With Allston’s encouragement he went to London in 1811, where he met Benjamin West, befriended Charles Robert Leslie, and was accepted as a student at the Royal Academy of Art.

Samuel F. B. Morse, Self-portrait (Oil on millboard, 1812, National Portrait Gallery, Smithsonian, Washington D.C.). This self-portrait was made when Morse was only twenty-one years old.

He remained in London for four years, meeting many celebrities and forming an intimate friendship with Charles R. Leslie, who became his room-mate. Under the tuition of Allston and Benjamin West he made rapid progress in his art, and in 1813 exhibited a colossal “Dying Hercules” in the Royal Academy, which was classed by critics as among the first twelve paintings there. The plaster model that he made to assist him in his picture gained the gold medal of the Adelphi society of arts.

This was given when Great Britain and the United States were at war, and was cited as an illustration of the impartiality with which American artists were treated by England. The first portrait that he painted abroad was of Leslie, who paid him a similar compliment, and later he executed one of Zerah Colburn. He then set to work on an historical composition to be offered in competition for the highest premium of tile Royal Academy, but, as he was obliged to return to the United States in August, 1815, this project was abandoned. Settling in Boston, he opened a studio in that city, but, while visitors were glad to admire his “Judgment of Jupiter,” his patrons were few. Finding no opportunities for historic painting, he turned his attention to portraits during 1816-’17, visiting the larger towns of Vermont and New Hampshire.

Meanwhile he was associated with his brother Sidney E. Morse, in the invention of an improved pump. In January, 1818, he went to Charleston. S. C., and there painted many portraits, his orders at one time exceeding 150 in number, but in the following winter he returned to Charleston, where he wrote to his old preceptor, Washington Allston: ” I am painting from morning till night, and have continual applications.”

Samuel F. B. Morse, Self-portrait (Oil on wood, 1818, Brick Store Museum, Kennebunk, ME)

Among his orders was a commission from the city authorities for a portrait of James Monroe, then president of the United States, which he painted in Washington, and which, on its completion, was placed in the city hall of Charleston.

Portrait of James Monroe (Oil on canvas, 1819-20, The White House, Washington D.C.)

On 6 Oct., 1818, Morse married Lucretia Walker, daughter of Charles Walker of Concord, N.H., by whom he had children, Charles Walker, Susan and James Edward Finley. In 1825, Lucretia died of heart trouble. Morse was so sad that he almost gave up painting. Finally he left his kids with the wife’s sister to paint in Europe again.

Portrait of Lucretia Pickering Walker Morse (Oil on panel, 1822, Mead art Museum, Amherst College)

Lucretia Morse & her Children (Oil on canvas, 1824, private collection)

In 1823 he settled in New York city, and after hiring as his studio “a fine room on Broadway, opposite Trinity churchyard,” he continued his painting of portraits, one of the first being that of Chancellor Kent, which was followed soon afterward by a picture of Fitz-Greene Halleck, now in the Astor library, and a full-length portrait of Lafayette for the city of New York. During his residence there he became associated with other artists in founding the New York drawing association, of which he was made president.

Marquis de Lafayette by Samuel Morse

This led in 1826 to the establishment of the National academy of the arts of design, to include representations from the arts of painting, sculpture, architecture, and engraving. Morse was chosen its president, and so remained until 1842. He also twice ran for Mayor of New York, but unsuccessfully.

He was likewise president of the Sketch club, an assemblage of artists that met weekly to sketch for an hour, after which the time was devoted to social entertainment, including a supper of “milk and honey, raisins, apples, and crackers.” About this time he delivered a series of lectures on “The Fine Arts ” before the New York athenveum, which are said to have been the first on that subject in the United States. Morse also patented a machine for cutting marble in 1823, by which he hoped to be able to produce perfect copies of any model.

Thus he continued until 1829, when he again visited Europe for study, and for three years resided abroad, principally in Paris and the art centers of Italy. This period culminated in the large Gallery of the Louvre (1832-33, Terra Museum of American Art, Chicago), a pictorial summation of European art with which he hoped to improve American culture after his return to New York in 1832.

Gallery of the Louvre by Samuel Morse

Strictly as an artist Morse did not exert a major impact on the stylistic development of nineteenth century American art, and his ideas and art appealed exclusively to the cultural elite. With the exception of the romantic Lafayette portrait, his most ambitious works failed before an unreceptive public. Unable to earn a living through painting historical subjects he was forced into portraiture, and many of these paintings are of negligible quality. Morse was further humiliated in 1837 when the Congressional Committee on Public Buildings decided not to commission him to paint a mural for the Capitol Rotunda.

This rejection may in part have been brought about by Morse’s reputation for radical politics; in the middle 1830s he became associated with the Native American party and wrote several widely-read and vitriolic anti-Catholic diatribes whose xenophobic tone bordered on paranoia. Disillusioned by failure, Morse ceased painting in 1837 at the age of forty-six, and devoted the last thirty-five years of his life to perfecting the electromagnetic telegraph.

During 1826-‘7 Prof. James F. Dana lectured on electromagnetism and electricity before the New York athenaeum. Mr. Morse was a regular attendant, and, being a friend of Prof. Dana, had frequent discussions with him on the subject of his lectures. But the first ideas of a practical application of electricity seem to have come to him while he was in Paris. James Fenimore Cooper refers to the event thus: “Our worthy friend first communicated to us his ideas on the subject of using the electric spark by way of a telegraph.

It was in Paris, and during the winter of 1831-‘2.” On 1 Oct., 1832, he sailed from Havre on the packet-ship “Sully ” for New York, and among his fellow-passengers was Charles T. Jackson, then lately from the laboratories of the great French physicists, where he had made special studies in electricity and magnetism. A conversation in the early part of the voyage turned on the recent experiments of Ampere with the electromagnet. When the question whether the velocity of electricity is retarded by the length of tile wire was asked, Dr. Jackson replied, referring to Benjamin Franklin’s experiments, that “electricity passes instantaneously over any known length of wire.” Morse then said : “If the presence of electricity can be made visible in any part of the circuit, I see no reason why intelligence may not be transmitted instantaneously by electricity.”

Samuel Morse’s Studio/Laboratory

The idea took fast hold of him, and thenceforth all his energy was devoted to the development of the electric telegraph. He said: “If it will go ten miles without stopping, I can snake it go around the globe.” At once, while on board the vessel, he set to work and devised the dot-and-dash alphabet. The electromagnetic and chemical recording telegraph essentially as it now exists was planned and drawn on shipboard, but he did not produce his working model till 1835 nor his relay till later. His brothers placed at his disposal a room on the fifth floor of the building on the corner of Nassau and Beeksnan streets, which he used as his studio, workshop, bedchamber, and kitchen. In this room, with his own hands, he first cut his models; then from these he made the moulds and castings, and in the lathe, with the graver’s tools, he gave them polish and finish.

Samuel Morse

In 1835 he was appointed professor of the literature of the arts of design in the University of the city of New York, and he occupied front rooms on the third floor in the north wing of the university building, looking out on Washington square. Here he made his apparatus, “made as it was,” he says, ” and completed before the first of the year 1836. I was enabled to and did mark down telegraphic intelligible signs, and to make and did snake distinguishable signs for telegraphing; and, having arrived at that point, I exhibited it to some of my friends early in that year, and among others to Prof. Leonard D. Gale.

” His discovery of the relay in 1835 made it possible for him to re-enforce the current after it had become feeble owing to its distance from the source, thus making possible transmission from one point on a main line, through great distances, by a single act of a single operator. In 1836-‘7 he directed his experiments mainly to modifying the marking apparatus, and later in varying the modes of uniting, experimenting with plumbago and various kinds of inks or coloring-matter, substituting a pen for a pencil, and devising a mode of writing on a whole sheet of paper instead of on a strip of ribbon.

First telegraph model, ca. 1835

Made from an old artist canvas stretcher, homemade battery and wooden clockworks. Code was generated by the wooden arm riding across the metal sawtooth dies representing dots and dashes and printed out on the paper tape moved by the clockworks.

In September, 1837, the instrument was shown in the cabinet of the university to numerous visitors, operating through a circuit of 1,700 feet of wire that ran back and forth in that room. It was the first instrument to transform information into electrical form and transmit it reliably over long distances. The original Morse telegraph did not use a key and sounder.

Instead it was a device designed to print patterns at a distance. The transmitter, in front, had code slugs shaped in hills and valleys. These represented the more familiar dots and dashes of Morse code. These patterns were printed at a distance by the receiver. It recreated the hills and valleys as the arm was pulled back and forth by an electro-magnet, which was responding to the signals sent by the transmitter.

The apparatus consisted of a train of clock-wheels to regulate the motion of a strip of paper about one and a half inches wide; three cylinders of wood, A, B, and C, over which the paper passed, and which were controlled by the clock-work D that was moved by the weight E.

A wooden pendulum, F, was suspended over tile centre of the cylinder B. In the lower part of the pendulum was fixed a ease in which a pencil moved easily and was kept in contact with the paper by a light weight. An electromagnet was fixed on the pendulum. The wire from the helices of the magnet passed to onto pole of the battery, and the other to the cup of mercury. The other pole of the battery was connected by a wire to the other cup of mercury.

Morse’s application for a patent, dated 28 Sept., 1837, was filed as a caveat at the U.S. patent-office, and in December of the same year he made a formal request of congress for aid to build a telegraph-line. The committee on commerce of the house of representatives, to which the petition had been referred, reported favorably, but the session closed without any action being taken. Francis O. J. Smith, of Spaine, chairman of the committee, became impressed with the value of this new application of electricity, and formed a partnership with Mr. Morse.

In May, 1838, Morse went to Europe in the hope of interesting foreign governments in the establishment of telegraph-lines, but he was unsuccessful in London. He obtained a patent in France, but it was practically useless, as it required the inventor to put his discovery into operation within two years, and telegraphs being a government monopoly no private lines were permissible. Mr. Morse was received with distinction by scientists in each country, and his apparatus was exhibited under the auspices of tile Academy of Sciences in Paris, and the Royal Society in London.

While in Paris during March, 1839, Morse, met inventor Jacques Louis Mande Daguerre, and became acquainted with his process of reproducing pictures by the action of sunlight on silver salts. He had previously experimented in the same lines while residing in New Haven, but without success. Morse promptly dispatched an account of the meeting, with an enthusiastic description of the French inventor’s revolutionary new photographic process, to the editor of the New York Observer in a letter of March 9, 1839. In June of the same year, after the French government had purchased the method from Daguerre, he communicated the details to Morse, who succeeded in acquiring the process, and was associated with John W. Draper in similar experiments. For some time afterward, until the telegraph absorbed his attention, he was engaged in experimenting toward the perfecting of the daguerreotype, and he shares with Prof. Draper the honor of being the first to make photographs of living persons.

This head-and-shoulders portrait of Morse is a daguerreotype made between 1844 and 1860 from the studio of Mathew B. Brady. It has been claimed that this portrait of Morse may be the first daguerreotype made in America. If not the first, it is among the earliest.

In this portrait, he demonstrated a sophisticated awareness of the camera through his steady composure and fixed gaze.

After an absence of eleven months he returned to New York in May, 1839, as he writes to Mr. Smith, “without a farthing in my pocket, and have to borrow even for my meals, and, even worse than this, I have incurred a debt of rent by my absence.” Four years of trouble and almost abject poverty followed, and at times he was reduced to such want that for twenty-four hours he was without food. His only support was derived from a few students that he taught art, and occasional portraits that he was commissioned to paint.

In the mean time, his foreign competitors – Wheatstone in England, and Steinheil in Bavaria – were receiving substantial aid and making efforts to induce congress to adopt their systems in the United States, while Morse, struggling to persuade his own countrymen of the merits of his system, although it was conceded by scientists to be the best he was unable to accomplish anything.

He persisted in bringing the matter before congress after congress, until at last a bill granting him $30,000 was passed by the house on 23 Feb., 1842, by a majority of eight, the vote standing 90 to 82. On the last day of the session he left the capitol thoroughly disheartened, but found next morning that his bill had been rushed through the senate without division on the night of 3 March, 1843.


In 1844, Morse finally filed for a patent (granted 1849) of the printing telegraph which he had been developing since 1832. Most of the mechanical development of Morse’s telegraph and its code was done by his assistants, most notably Alfred Vail and William Baxter. However, all advanced modifications of the Morse’s telegraph were based on an electrical circuit consisting of a battery, a key, and an electromagnet, all connected by wire. The battery created the electricity that traveled along the wire. The key, located at one end of the wire, completed the electrical circuit when depressed. Morse’s important contribution was that he based his receiver on the electromagnet.

This feature ultimately ensured the universal adoption of his system. When the electromagnet was energized by a pulse of current from the sender, a soft iron armature was attracted to the magnet, producing a V-shaped deflection in the straight line being recorded on a moving strip of paper by a pencil attached to the armature. The grouping of a succession of such marks symbolized the words of a message. Morse soon devised a code whereby letters and numbers were represented by combinations of dot and dash symbols, which corresponded to signals of short and long duration.

You can translate words into the Morse code using this Shockwave Flash animated page.

Morse Telegraph Key, 1844-45, with improvements by Alfred Vail (1807-59) to the original invented by Samuel F.B. Morse.

The telegraph key Samuel Morse used on his first line in 1844 was very simple–a strip of spring steel that could be pressed against a metal contact. Alfred Vail, Morse’s partner, designed this key, in which the gap was more easily adjustable because of changes in its spring tension. It was used on the expanding telegraph system, perhaps as early as the fall of 1844 and certainly by 1845.

Morse/Vail telegraph register, 1844.

With the aid of Alfred Vail, the original receiver was greatly improved and adapted to print the Morse code.

There were yet many difficulties to be overcome, and with renewed energy he began to work. His intention was to place the wires in leaden pipes, buried in the earth. This proved impracticable, and other methods were devised. Ezra Cornell then became associated with him, and was charged with the laying of the wires, and after various accidents it was ultimately decided to suspend the wires, insulated, on poles in the air. These difficulties had not been considered, as it was supposed that the method of burying the wires, which had been adopted abroad, would prove successful. Nearly a year had been exhausted in making experiments, and the congressional appropriation was nearly consumed before the system of poles was resorted to. The construction of the line between Baltimore and Washington, a distance of about forty miles, was quickly accomplished, and on 11 May, 1844, Mr. Morse wrote to his assistant, Alfred Vail, in Baltimore, “Everything worked well.

” Among the earliest messages, while the line was still in an experimental condition, was one from Baltimore announcing the nomination of Henry Clay to the presidency by the Whig convention in that city. The news was conveyed on the railroad to the nearest point that had been reached by the telegraph, and then instantly transmitted over the wires to Washington. An hour later passengers arriving at Washington were surprised to find that the news had preceded them. By the end of the month communication between the two cities was complete, and practically perfect.

The day that was chosen for the public exhibition was 24 May, 1844, when Mr. Morse invited his friends to assemble in the chamber of the U.S. Supreme Court, in the capitol, at Washington, while his assistant, Mr. Vail, was in Baltimore, at the Mount Claire depot. Miss Annie G. Ellsworth, daughter of Henry L. Ellsworth. then commissioner of patents, chose the words of the message.

As she had been the first to announce to Mr. Morse the passage of the bill granting the appropriation to build the line, he had promised her this distinction. She selected the words “What hath God wrought,” taken from the Bible (Numbers xxiii., 23). They were received at once by Mr. Vail, and sent back again in an instant. The strip of paper on which the telegraphic characters were printed was claimed by Gov. Thomas H. Seymour, of Connecticut, on the ground that Miss Ellsworth was a native of Hartford, and is now preserved in the archives by the Hartford athenaeum.

Two days later the national Democratic convention met in Baltimore and nominated James K. Polk for the presidency. Silas Wright, of New York, was then chosen for the vice-presidency, and the information was immediately conveyed by telegraph to Morse, and by him communicated to Mr. Wright, then in the senate chamber. A few minutes later the convention was astonished by receiving a telegram from Mr. Wright declining the nomination. The despatch was at once read before the convention, but the members were so incredulous that there was an adjournment to await the report of a committee that was sent to Washington to get reliable information on the subject.

Morse offered his telegraph to the U. S. government for $100,000, but, while $8,000 was voted for maintenance of the initial line, any further expenditure in that direction was declined. The patent then passed into private hands, and the Morse system became the property of a joint-stock company called the Magnetic telegraph company. Step by step, sometimes with rapid strides, but persistently, the telegraph spread over the United States, although not without accompanying difficulties. Morse’s patents were violated, his honor disputed, and even his integrity was assailed, and rival companies devoured for a time all the profits of the business, but after a series of vexatious lawsuits his rights were affirmed by the U.S. supreme court. In 1846 he was granted an extension of his patent, and ultimately the Morse system was adopted in France, Germany, Denmark, Sweden, Russia, and Australia.

The following statement, made in 1869 by the Western Union telegraph company, the largest corporation of its kind in the world, is still true: “Nearly all the machinery employed by the company belongs to the Morse system. This telegraph is now used almost exclusively everywhere, and the time will probably never come when it will cease to be the leading system of the world. Of more than a hundred devices that have been made to supersede it, not one has succeeded in accomplishing its purpose, and it is used at the present time upon more than ninety-five per cent of all the telegraph-lines in existence.”

The establishment of the submarine telegraph is likewise due to Morse. In October, 1842, he made experiments with a cable between Castle Garden and Governor’s island. The results were sufficient to show the practicability of such an undertaking. Later he held the office of electrician to the New York, Newfoundland, and London telegraph company, organized for the purpose of laying a cable across the Atlantic ocean.

Photograph of Morse, ca. 1845, with his hand on a telegraph

On August 10, 1848, Morse married for a second time. There had been a number of rumours of romantic associations, although nothing came of them until at a family wedding he met a second cousin named Sarah E. Griswold (b. 25 Dec 1822, Sault Ste Marie, MI, USA – d. 14 Nov 1901, Berlin, Germany). He was particularly struck by the way she responded to one of his son’s who had learning difficulties. Sarah, herself was born with poor hearing and had a speech defect.

The relationship grew quickly and they were soon married. There was some family disapproval of the marriage. Sarah was less than half his age and some thought she might have married Morse for his wealth. Sarah strongly denied this saying that if Morse lost all his wealth she would support him herself. As proof of the strength of their relationship, this period proved to be the happiest in his life.

Morse’s house “Locust Grove”

Samuel Morse and his new wife, Sarah E. Griswold, lived in the house that Morse purchased in 1847 on the east bank of the Hudson, near Poughkeepsie, which they called “Locust Grove”. They dispensed a generous hospitality, entertaining eminent artists and other notable persons. Soon afterward Morse bought a city residence on Twenty-second street, where he spent the winters, and on whose front since his death a marble tablet has been inserted, bearing the inscription, “In this house S.F.B. Morse lived for many years and died.”

Morse was a ready writer, and, in addition to several controversial pamphlets concerning the telegraph, he published poems and articles in the “North American Review.” He edited the “Remains of Lucretia Maria Davidson” (New York, 1829), to which he added a personal memoir, and also published “Foreign Conspiracy against the Liberties of the United States” (1835) ; “Eminent Dangers to the Free institutions of the United States through Foreign Immigration, and the Present State of the Naturalization Laws, by an American,” originally contributed to the “Journal of Commerce” in 1835, and published anonymously in 1854; “Confessions of a French Catholic Priest, to which are added Warnings to the People of the United States, by the same Author” (edited and published with an introduction, 1837); and “Our Liberties defended, the Question discussed, Is the Protestant or Papal System most Favorable to Civil and Religious Liberty?” (1841). Samuel Morse also edited and wrote geography textbooks. Some Morse’s papers are available in the Internet.

He had many honors. Yale gave him the degree of LL. D. in 1846, and in 1842 the American Institute gave him its gold medal for his experiments. In 1830 he was elected a corresponding member of the Historical Institute of France, in 1837 a member of the Royal Academy of Fine Arts in Belgium, in 1841 corresponding member of the National institution for the promotion of science in Washington, in 1845 corresponding member of the Archaeological Society of Belgium, in 1848 a member of the American Philosophical Society, and in 1849 a fellow of the American Academy of Arts and Sciences.

The sultan of Turkey presented him in 1848 with the decoration of Nishan Htichar, or order of glory, set in diamonds. A golden snuff-box, containing the Prussian golden medal for scientific merit, was sent him in 1851; the great gold medal of arts and sciences was awarded him by Whrtemberg in 1852, and in 1855 the emperor of Austria sent him the great gold medal of science and art. France made him a chevalier of the Legion of honor in 1856, Denmark conferred on him the cross of the order of the Dannebrog in 1856, Spain gave him the honor of knighthood and made him commander of the royal order of Isabella the Catholic in 1859, Portugal made him a knight of the tower and sword in 1860, and Italy conferred on him the insignia of chevalier of the royal order of Saints Lazaro Mauritio in 1864.

In his later years, Morse, a patriarchal figure, attained recognition at home and abroad which is seldom accorded a living hero of the arts of peace. As a wealthy man, he was generous in giving funds to colleges, including Yale and Vassar, benevolent societies and to poor artists.

In 1856 the telegraph companies of Great Britain gave him a banquet in London. At the instance of Napoleon III., emperor of the French, representatives of France, Austria, Sweden, Russia, Sardinia, the Netherlands, Turkey, Holland, the Papal States, and Tuscany, met in Paris during August, 1858, to decide upon a collective testimonial to Morse, and the result, of their deliberations was a vote of 400,000 francs. During the same year the American colony of France entertained him at a dinner given in Paris, over which John S. Preston presided. On the occasion of his later visits to Europe he was received with great distinction.

Daguerreotypes of Samuel Morse in the old age

Morse statue in the Central Park

As he was returning from abroad in 1868 he received an invitation from his fellow-citizens, who united in saying “Many of your fellow countrymen and numerous personal friends desire to give a definite expression of the fact that this country is in full accord with European nations in acknowledging your title to the position of the father of the modern telegraph, and at the same time in a fitting manner to welcome you to your home.” The day selected was 30 Dec., 1868, and Salmon P. Chase, chief justice of the U.S. supreme court, presided at the banquet in New York. On 10 June, 1871, he was further honored by the erection of a bronze statue in the Central Park, NY. Voluntary contributions had been gathered for two years from those who in various ways were connected with the electric telegraph.

The statue is of heroic size, modeled by Byron M. Pickett, and represents Morse as holding the first message that was sent over the wires. In the evening of the same day a reception was held in the Academy of Music, at which many eminent men of the nation were present. At the hour of nine the chairman announced that the telegraphic instrument before him, tile original register employed in actual service, was connected with all the wires of the United States, and that the touch of the finger on the key would soon vibrate throughout the continent.

The following message was then sent: “Greeting and thanks to the telegraph fraternity throughout the land. Glory to God in the highest, on earth peace, good will to men.” At the last click of the instrument, Morse struck the sounder with his own name, amid the most extravagant applause. When the excitement had subsided, the chairman said: “Thus the father of the telegraph bids farewell to his children.”

This 4.25″x6.5″ albumin print of Samuel Finley Breese Morse with his first Daguerreotype camera was found “tipped-in” to a page of a book. A Daguerreotype plate holder is leaning against the front of the camera and on the far right of the photograph is his mercury development box. The camera is turned on the side (the bottom of the camera is towards Morse.) This camera is now in the possession of the United States National Museum.

Samuel Morse’s Daguerreotype Camera

The last public service that he performed was the unveiling of the statue of Benjamin Franklin in Printing house square, on 17 Jan., 1872, in the presence of a vast number of citizens, he had cheerfully acceded to the request that he would perform this act, remarking that it would be his last. It was eminently appropriate that he should do this, for, as was said : “The one conducted the lightning safely from the sky; the other conducts it beneath the ocean, from continent to continent.

The one tamed the lightning, the other makes it minister to human wants and human progress.” Shortly after his return to his home he was seized with neuralgia in his head, and after a few months of suffering he died of pneumonia on 2 April, 1872, in New York City, at the age of 81. He died peacefully in a home he and Sarah maintained in New York as their winter house. Memorial sessions of congress and of various state legislatures were held in his honor. He was buried in Brooklyn’s Greenwood Cemetery.

Before his death Morse’s invention of the telegraph had eclipsed his early renown as a painter, and it was only after the retrospective exhibition of his work held at the Metropolitan Museum of Art in 1932 that interest in his art revived.

Large Medallion issued by the Monnaie de Paris in 1973 in memory of Samuel Finlay Breeze Morse – inventor of Morse code. Obverse: Bust of Morse with Morse code around edges. Reverse: Diagram of the first electronic telegraph invented by Morse. As struck, this fine medallion comes in an official issue Blue card box together with a plastic “Monnaie de Paris” stand.

A US postal stamp memorizing Samuel Morse was released on October 7, 1940.

A book about Morse written by John H. Tiner and illustrated by Shirley Young is recommended for reading: “Samuel F. B. Morse: Artist with a Message”


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Michael Faraday

English physicist and chemist whose many experiments contributed greatly to the understanding of electromagnetism. Faraday, who became one of the greatest scientists of the 19th century, began his career as a chemist. Many consider him the greatest experimentalist who ever lived. Several concepts that he derived directly from experiments, such as lines of magnetic force, have become common ideas in modern physics.

He wrote a manual of practical chemistry that reveals his mastery of the technical aspects of his art, discovered a number of new organic compounds, among them benzene, and was the first to liquefy a “permanent” gas (i.e., one that was believed to be incapable of liquefaction). His major contribution, however, was in the field of electricity and magnetism.

He was the first to produce an electric current from a magnetic field, invented the first electric motor and dynamo, demonstrated the relation between electricity and chemical bonding, discovered the effect of magnetism on light, and discovered and named diamagnetism, the peculiar behaviour of certain substances in strong magnetic fields. He provided the experimental, and a good deal of the theoretical, foundation upon which James Clerk Maxwell erected classical electromagnetic field theory.

He introduced several words that we still use today to discuss electricity: ion, electrode, cathode, and anode. Early life: Michael Faraday was born on Sept. 22, 1791 in a poor and very religious family in the country village of Newington, Surrey, now a part of South London. His father was a blacksmith who had migrated from the north of England earlier in 1791 to look for work. His mother was a country woman of great calm and wisdom who supported her son emotionally through a difficult childhood.

Faraday was one of four children, all of whom were hard put to get enough to eat, since their father was often ill and incapable of working steadily. Faraday later recalled being given one loaf of bread that had to last him for a week. The family belonged to a small Christian sect, called Sandemanians, that provided spiritual sustenance to Faraday throughout his life.

It was the single most important influence upon him and strongly affected the way in which he approached and interpreted nature. Faraday himself, shortly after his marriage, at the age of thirty, joined the same sect, to which he adhered till his death. Religion and science he kept strictly apart, believing that the data of science were of an entirely different nature from the direct communications between God and the soul on which his religious faith was based.

Faraday received only the rudiments of an education, learning to read, write, and cipher in a church Sunday school. At an early age he began to earn money by delivering newspapers for a book dealer and bookbinder, and at the age of 14 he was apprenticed to the man. Unlike the other apprentices, Faraday took the opportunity to read some of the books brought in for rebinding. The article on electricity in the third edition of the Encyclopadia Britannica particularly fascinated him. Using old bottles and lumber, he made a crude electrostatic generator and did simple experiments. He also built a weak voltaic pile with which he performed experiments in electrochemistry.

He was also among other young Londoners who persued an interest in science by gathering to hear talks at the City Philosophical Society. Faraday’s great opportunity came when he was offered a free ticket to attend chemical lectures by Sir Humphry Davy at the Royal Institution of Great Britain in London. Faraday went, sat absorbed with it all, recorded the lectures in his notes, and returned to bookbinding with the seemingly unrealizable hope of entering the temple of science.

He sent a bound copy of his notes to Davy along with a letter asking for employment, but there was no opening. Davy did not forget, however, and, when one of his laboratory assistants was dismissed for brawling, he offered Faraday a job. His first assignment was to accompany Sir Humphry and his wife on a tour of the Continent, during which he sometimes had to be a personal servant to Lady Davy. Then Faraday began as Davy’s laboratory assistant and learned chemistry at the elbow of one of the greatest practitioners of the day. It has been said, with some truth, that Faraday was Davy’s greatest discovery.

When Faraday joined Davy in 1812, Davy was in the process of revolutionizing the chemistry of the day. Antoine-Laurent Lavoisier, the Frenchman generally credited with founding modern chemistry, had effected his rearrangement of chemical knowledge in the 1770s and 1780s by insisting upon a few simple principles. Among these was that oxygen was a unique element, in that it was the only supporter of combustion and was also the element that lay at the basis of all acids. Davy, after having discovered sodium and potassium by using a powerful current from a galvanic battery to decompose oxides of these elements, turned to the decomposition of muriatic (hydrochloric) acid, one of the strongest acids known.

The products of the decomposition were hydrogen and a green gas that supported combustion and that, when combined with water, produced an acid. Davy concluded that this gas was an element, to which he gave the name chlorine, and that there was no oxygen whatsoever in muriatic acid. Acidity, therefore, was not the result of the presence of an acid-forming element but of some other condition. What else could that condition be but the physical form of the acid molecule itself? Davy suggested, then, that chemical properties were determined not by specific elements alone but also by the ways in which these elements were arranged in molecules. In arriving at this view he was influenced by an atomic theory that was also to have important consequences for Faraday’s thought.

This theory, proposed in the 18th century by Ruggero Giuseppe Boscovich, argued that atoms were mathematical points surrounded by alternating fields of attractive and repulsive forces. A true element comprised a single such point, and chemical elements were composed of a number of such points, about which the resultant force fields could be quite complicated. Molecules, in turn, were built up of these elements, and the chemical qualities of both elements and compounds were the results of the final patterns of force surrounding clumps of point atoms. One property of such atoms and molecules should be specifically noted: they can be placed under considerable strain, or tension, before the “bonds” holding them together are broken. These strains were to be central to Faraday’s ideas about electricity.

Faraday’s second apprenticeship, under Davy, came to an end in 1820. By then he had learned chemistry as thoroughly as anyone alive. He had also had ample opportunity to practice chemical analyses and laboratory techniques to the point of complete mastery, and he had developed his theoretical views to the point that they could guide him in his researches. There followed a series of discoveries that astonished the scientific world.

Michael Faraday

Engraving after an original work by Charles Turner (1773-1857)
Faraday achieved his early renown as a chemist. As his chemical capabilities increased, he was given more responsibility. In 1825 he replaced the seriously ailing Davy in his duties directing the laboratory at the Royal Institution. In 1833 he was appointed to the Fullerian Professorship of Chemistry-a special research chair created for him. His reputation as an analytical chemist led to his being called as an expert witness in legal trials and to the building up of a clientele whose fees helped to support the Royal Institution.

In 1820 he produced the first known compounds of carbon and chlorine, C2Cl6 and C2Cl4. These compounds were produced by substituting chlorine for hydrogen in “olefiant gas” (ethylene), the first substitution reactions induced. (Such reactions later would serve to challenge the dominant theory of chemical combination proposed by Jons Jacob Berzelius.) In 1825, as a result of research on illuminating gases, Faraday isolated and described benzene.

In the 1820s he also conducted investigations of steel alloys, helping to lay the foundations for scientific metallurgy and metallography. While completing an assignment from the Royal Society of London to improve the quality of optical glass for telescopes, he produced a glass of very high refractive index that was to lead him, in 1845, to the discovery of diamagnetism.

In 1821 he married Sarah Barnard, settled permanently at the Royal Institution, and began the series of researches on electricity and magnetism that was to revolutionize physics.

Faraday announcing his discovery to his wife on Christmas morning, 1821 (from “Electricity in Daily Life”, C.F. Brackett et al., 1890)

Michael Faraday with his wife Sarah

Faraday’s research into electricity and electrolysis was guided by the belief that electricity is only one of the many manifestations of the unified forces of nature, which included heat, light, magnetism, and chemical affinity. Although this idea was erroneous, it led him into the field of electromagnetism, which was still in its infancy. In 1785, Charles Coulomb had been the first to demonstrate the manner in which electric charges repel one another, and it was not until 1820 that Hans Christian Oersted and Andre Marie Ampere discovered that an electric current produces a magnetic field.

Faraday’s ideas about conservation of energy led him to believe that since an electric current could cause a magnetic field, a magnetic field should be able to produce an electric current. He demonstrated this principle of induction in 1831. Faraday expressed the electric current induced in the wire in terms of the number of lines of force that are cut by the wire. The principle of induction was a landmark in applied science, for it made possible the dynamo, or generator, which produces electricity by mechanical means.

Faraday’s introduction of the concept of lines of force was rejected by most of the mathematical physicists of Europe, since they assumed that electric charges attract and repel one another, by action at a distance, making such lines unnecessary. Faraday had demonstrated the phenomenon of electromagnetism in a series of experiments, however. Faraday’s descriptive theory of lines of force moving between bodies with electrical and magnetic properties enabled James Clerk Maxwell to formulate an exact mathematical theory of the propagation of electromagnetic waves.

In 1865, Maxwell proved mathematically that electromagnetic phenomena are propagated as waves through space with the velocity of light, thereby laying the foundation of radio communication confirmed experimentally in 1888 by Hertz and developed for practical use by Guglielmo Marconi at the turn of the century.

In 1820 Hans Christian Orsted had announced the discovery that the flow of an electric current through a wire produced a magnetic field around the wire. Andre-Marie Ampere showed that the magnetic force apparently was a circular one, producing in effect a cylinder of magnetism around the wire. No such circular force had ever before been observed, and Faraday was the first to understand what it implied. If a magnetic pole could be isolated, it ought to move constantly in a circle around a current-carrying wire. Faraday’s ingenuity and laboratory skill enabled him to construct an apparatus that confirmed this conclusion. This device, which transformed electrical energy into mechanical energy, was the first electric motor.

This discovery led Faraday to contemplate the nature of electricity. Unlike his contemporaries, he was not convinced that electricity was a material fluid that flowed through wires like water through a pipe. Instead, he thought of it as a vibration or force that was somehow transmitted as the result of tensions created in the conductor. One of his first experiments after his discovery of electromagnetic rotation was to pass a ray of polarized light through a solution in which electrochemical decomposition was taking place in order to detect the intermolecular strains that he thought must be produced by the passage of an electric current. During the 1820s he kept coming back to this idea, but always without result.

In the spring of 1831 Faraday began to work with Charles (later Sir Charles) Wheatstone on the theory of sound, another vibrational phenomenon. He was particularly fascinated by the patterns (known as Chladni figures) formed in light powder spread on iron plates when these plates were thrown into vibration by a violin bow. Here was demonstrated the ability of a dynamic cause to create a static effect, something he was convinced happened in a current-carrying wire. He was even more impressed by the fact that such patterns could be induced in one plate by bowing another nearby.

Such acoustic induction is apparently what lay behind his most famous experiment. On August 29, 1831, Faraday wound a thick iron ring on one side with insulated wire that was connected to a battery. He then wound the opposite side with wire connected to a galvanometer. What he expected was that a “wave” would be produced when the battery circuit was closed and that the wave would show up as a deflection of the galvanometer in the second circuit. He closed the primary circuit and, to his delight and satisfaction, saw the galvanometer needle jump.

A current had been induced in the secondary coil by one in the primary. When he opened the circuit, however, he was astonished to see the galvanometer jump in the opposite direction. Somehow, turning off the current also created an induced current in the secondary circuit, equal and opposite to the original current. This phenomenon led Faraday to propose what he called the “electrotonic” state of particles in the wire, which he considered a state of tension. A current thus appeared to be the setting up of such a state of tension or the collapse of such a state. Although he could not find experimental evidence for the electrotonic state, he never entirely abandoned the concept, and it shaped most of his later work.

In the fall of 1831 Faraday attempted to determine just how an induced current was produced. His original experiment had involved a powerful electromagnet, created by the winding of the primary coil. He now tried to create a current by using a permanent magnet. He discovered that when a permanent magnet was moved in and out of a coil of wire a current was induced in the coil. Magnets, he knew, were surrounded by forces that could be made visible by the simple expedient of sprinkling iron filings on a card held over them. Faraday saw the “lines of force” thus revealed as lines of tension in the medium, namely air, surrounding the magnet, and he soon discovered the law determining the production of electric currents by magnets: the magnitude of the current was dependent upon the number of lines of force cut by the conductor in unit time. He immediately realized that a continuous current could be produced by rotating a copper disk between the poles of a powerful magnet and taking leads off the disk’s rim and centre.

The outside of the disk would cut more lines than would the inside, and there would thus be a continuous current produced in the circuit linking the rim to the centre. This was the first dynamo. It was also the direct ancestor of electric motors, for it was only necessary to reverse the situation, to feed an electric current to the disk, to make it rotate.

On 29th August 1831, using his “induction ring”, Faraday made one of his greatest discoveries – electromagnetic induction: the “induction” or generation of electricity in a wire by means of the electromagnetic effect of a current in another wire. The induction ring was the first electric transformer. In a second series of experiments in September he discovered magneto-electric induction: the production of a steady electric current. To do this, Faraday attached two wires through a sliding contact to a copper disc. By rotating the disc between the poles of a horseshoe magnet he obtained a continuous direct current. This was the first generator.

Although neither of Faraday’s devices is of practical use today they enhanced immeasurably the theoretical understanding of electricity and magnetism. He described these experiments in two papers presented to the Royal Society on 24th November 1831, and 12th January 1832. These were the first and second parts of his “Experimental researches into electricity” in which he gave his “law which governs the evolution of electricity by magneto-electric induction”. After reading this, a young Frenchman, Hippolyte Pixii, constructed an electric generator that utilized the rotary motion between magnet and coil rather than Faraday’s to and fro motion in a straight line. All the generators in power stations today are direct descendants of the machine developed by Pixii from Faraday’s first principles.

It was characteristic of Faraday’s devotion to the enlargement of the bounds of human knowledge that on his discovery of magneto-electricity he abandoned the commercial work by which he had added to his small salary, in order to reserve all his energies for research. This financial loss was in part made up later by a pension of 300 pounds a year from the British Government.

Theory of electrochemistry:

While Faraday was performing these experiments and presenting them to the scientific world, doubts were raised about the identity of the different manifestations of electricity that had been studied. Were the electric “fluid” that apparently was released by electric eels and other electric fishes, that produced by a static electricity generator, that of the voltaic battery, and that of the new electromagnetic generator all the same? Or were they different fluids following different laws? Faraday was convinced that they were not fluids at all but forms of the same force, yet he recognized that this identity had never been satisfactorily shown by experiment. For this reason he began, in 1832, what promised to be a rather tedious attempt to prove that all electricities had precisely the same properties and caused precisely the same effects. The key effect was electrochemical decomposition.

Voltaic and electromagnetic electricity posed no problems, but static electricity did. As Faraday delved deeper into the problem, he made two startling discoveries. First, electrical force did not, as had long been supposed, act at a distance upon chemical molecules to cause them to dissociate. It was the passage of electricity through a conducting liquid medium that caused the molecules to dissociate, even when the electricity merely discharged into the air and did not pass into a “pole” or “centre of action” in a voltaic cell. Second, the amount of the decomposition was found to be related in a simple manner to the amount of electricity that passed through the solution.

These findings led Faraday to a new theory of electrochemistry. The electric force, he argued, threw the molecules of a solution into a state of tension (his electrotonic state). When the force was strong enough to distort the fields of forces that held the molecules together so as to permit the interaction of these fields with neighbouring particles, the tension was relieved by the migration of particles along the lines of tension, the different species of atoms migrating in opposite directions. The amount of electricity that passed, then, was clearly related to the chemical affinities of the substances in solution. These experiments led directly to Faraday’s two laws of electrochemistry: (1) The amount of a substance deposited on each electrode of an electrolytic cell is directly proportional to the quantity of electricity passed through the cell. (2) The quantities of different elements deposited by a given amount of electricity are in the ratio of their chemical equivalent weights.

Michael Faraday (1841/42)

Faraday’s work on electrochemistry provided him with an essential clue for the investigation of static electrical induction. Since the amount of electricity passed through the conducting medium of an electrolytic cell determined the amount of material deposited at the electrodes, why should not the amount of electricity induced in a nonconductor be dependent upon the material out of which it was made? In short, why should not every material have a specific inductive capacity? Every material does, and Faraday was the discoverer of this fact.

The portrate shown here was painted by Thomas Phillips (1770-1845), oil on canvas, The National Portrait Gallery, London.

Michael Faraday (ca. 1844-60)

By 1839 Faraday was able to bring forth a new and general theory of electrical action. Electricity, whatever it was, caused tensions to be created in matter. When these tensions were rapidly relieved (i.e., when bodies could not take much strain before “snapping” back), then what occurred was a rapid repetition of a cyclical buildup, breakdown, and buildup of tension that, like a wave, was passed along the substance.

Such substances were called conductors. In electrochemical processes the rate of buildup and breakdown of the strain was proportional to the chemical affinities of the substances involved, but again the current was not a material flow but a wave pattern of tensions and their relief. Insulators were simply materials whose particles could take an extraordinary amount of strain before they snapped. Electrostatic charge in an isolated insulator was simply a measure of this accumulated strain. Thus, all electrical action was the result of forced strains in bodies.

The strain on Faraday of eight years of sustained experimental and theoretical work was too much, and in 1839 his health broke down. For the next six years he did little creative science. Not until 1845 was he able to pick up the thread of his researches and extend his theoretical views.

Michael Faraday (ca. 1849) lithograph by W. Bosley from A. F. J. Claudet daguerreotype
Smithsonian Archives

Faraday had scientific discussions and collaborations with many famous scientists of his time.

Group of scientists: (from left to right) English physicist and chemist Michael Faraday (1791 – 1867), English biologist Thomas Huxley (1825 – 1895), English physicist Sir Charles Wheatley (1802 – 1875), Scottish physicist Sir David Brewster (1781 – 1868) and Irish physicist John Tyndall (1820 – 1893).

Later life:

Since the very beginning of his scientific work, Faraday had believed in what he called the unity of the forces of nature. By this he meant hat all the forces of nature were but manifestations of a single universal force and ought, therefore, to be convertible into one another. In 1846 he made public some of the speculations to which this view led him.

A lecturer, scheduled to deliver one of the Friday evening discourses at the Royal Institution by which Faraday encouraged the popularization of science, panicked at the last minute and ran out, leaving Faraday with a packed lecture hall and no lecturer. On the spur of the moment, Faraday offered “Thoughts on Ray Vibrations.” Specifically referring to point atoms and their infinite fields of force, he suggested that the lines of electric and magnetic force associated with these atoms might, in fact, serve as the medium by which light waves were propagated. Many years later, Maxwell was to build his electromagnetic field theory upon this speculation.

Professor Faraday delivering a lecture at the Royal Institution. Members of the Royal Instsitution attend a lecture given by Professor Faraday on Magnetism and Light, London 1846.

Inventor and scientist Michael Faraday lectures at the Royal Institution. The Prince Consort with his sons the Prince of Wales and the Duke of Edinburgh are seated in the front row facing Faraday. From a painting by Alexander Blaikley.

Every year on Christmas Day, he presented his Faraday Lectures for Children which were crowded with interested listeners. The Royal Institution Christmas lectures for children, begun by Faraday, continue to this day.

Faraday described his numerous experiments in electricity and electromagnetism in three volumes entitled Experimental Researches in Electricity (1839, 1844, 1855); his chemical work was chronicled in Experimental Researches in Chemistry and Physics (1858). Faraday ceased research work in 1855 because of declining mental powers, but he continued as a lecturer until 1861. A series of six children’s lectures published in 1860 as The Chemical History of a Candle, has become a classic of science literature.

When Faraday returned to active research in 1845, it was to tackle again a problem that had obsessed him for years, that of his hypothetical electrotonic state. He was still convinced that it must exist and that he simply had not yet discovered the means for detecting it. Once again he tried to find signs of intermolecular strain in substances through which electrical lines of force passed, but again with no success. It was at this time that a young Scot, William Thomson (later Lord Kelvin), wrote Faraday that he had studied Faraday’s papers on electricity and magnetism and that he, too, was convinced that some kind of strain must exist. He suggested that Faraday experiment with magnetic lines of force, since these could be produced at much greater strengths than could electrostatic ones.

Faraday took the suggestion, passed a beam of plane-polarized light through the optical glass of high refractive index that he had developed in the 1820s, and then turned on an electromagnet so that its lines of force ran parallel to the light ray. This time he was rewarded with success. The plane of polarization was rotated, indicating a strain in the molecules of the glass.

But Faraday again noted an unexpected result. When he changed the direction of the ray of light, the rotation remained in the same direction, a fact that Faraday correctly interpreted as meaning that the strain was not in the molecules of the glass but in the magnetic lines of force. The direction of rotation of the plane of polarization depended solely upon the polarity of the lines of force; the glass served merely to detect the effect. Faraday’s discovery (1845) that an intense magnetic field can rotate the plane of polarized light is known today as the Faraday effect. The phenomenon has been used to elucidate molecular structure and has yielded information about galactic magnetic fields.

This discovery confirmed Faraday’s faith in the unity of forces, and he plunged onward, certain that all matter must exhibit some response to a magnetic field. To his surprise he found that this was in fact so, but in a peculiar way. Some substances, such as iron, nickel, cobalt, and oxygen, lined up in a magnetic field so that the long axes of their crystalline or molecular structures were parallel to the lines of force; others lined up perpendicular to the lines of force.

Substances of the first class moved toward more intense magnetic fields; those of the second moved toward regions of less magnetic force. Faraday named the first group paramagnetics and the second diamagnetics. After further research he concluded that paramagnetics were bodies that conducted magnetic lines of force better than did the surrounding medium, whereas diamagnetics conducted them less well. By 1850 Faraday had evolved a radically new view of space and force. Space was not “nothing,” the mere location of bodies and forces, but a medium capable of supporting the strains of electric and magnetic forces. The energies of the world were not localized in the particles from which these forces arose but rather were to be found in the space surrounding them. Thus was born field theory. As Maxwell later freely admitted, the basic ideas for his mathematical theory of electrical and magnetic fields came from Faraday; his contribution was to mathematize those ideas in the form of his classical field equations.

Michael Faraday’s concern about contemporary environmental concerns caricatured. A cartoon depicting English chemist and physicist Professor Michael Faraday holding his nose from a smell as he gives his card to ‘Father Thames’.

From about 1855, Faraday’s mind began to fail. He still did occasional experiments, one of which involved attempting to find an electrical effect of raising a heavy weight, since he felt that gravity, like magnetism, must be convertible into some other force, most likely electrical. This time he was disappointed in his expectations, and the Royal Society refused to publish his negative results. More and more, Faraday began to sink into senility. Queen Victoria rewarded his lifetime of devotion to science by granting him the use of a house at Hampton Court and even offered him the honour of a knighthood. Faraday gratefully accepted the cottage but rejected the knighthood; he would, he said, remain plain Mr. Faraday to the end. In contrast to Davy, Faraday was known throughout his life as a kind and humble person, unconcerned with honors and eager to practice his science to the best of his ability. In 1865, Faraday ended his connection with the Royal Institution after over 50 years of service. He died at his house at Hampton Court on 25th August 1867 and was buried in Highgate Cemetery, London, leaving as his monument a new conception of physical reality.

His discoveries have had an incalculable effect on subsequent scientific and technical development. He was a true pioneer of scientific discovery. The discoveries made by Faraday were so numerous, and often demand so detailed a knowledge of chemistry and physics before they can be understood, that it is impossible to attempt to describe or even enumerate them here. Among the most important are the discovery of magneto-electric induction, of the law of electro-chemical decomposition, of the magnetization of light, and of diamagnetism.

Round each of these are grouped numbers of derivative but still highly important additions to scientific knowledge, and together they form so vast an achievement as to lead his successor, Tyndall, to say, “Taking him for all and all, I think it will be conceded that Michael Faraday was the greatest experimental philosopher the world has ever seen; and I will add the opinion, that the progress of future research will tend, not to dim or to diminish, but to enhance and glorify the labours of this mighty investigator.”

Two electrical units (for capacitance and charge) were named after Michael Faraday to honor his accomplishments:

Farad (F) is the SI unit of electric capacitance. Very early in the study of electricity scientists discovered that a pair of conductors separated by an insulator can store a much larger charge than an isolated conductor can store. The better the insulator, the larger the charge that the conductors can hold. This property of a circuit is called capacitance, and it is measured in farads.

One farad is defined as the ability to store one coulomb of charge per volt of potential difference between the two conductors. This is a natural definition, but the unit it defines is very large. In practical circuits, capacitance is often measured in microfarads, nanofarads, or sometimes even in picofarads (10-12 farad, or trillionths of a farad).

Faraday (Fd) is a unit of electric charge. In a process called electrolysis, chemists separate the components of a dissolved chemical compound by passing an electric current through the compound. The components are deposited at the electrodes, where the current enters or leaves the solution.

The British electrochemist and physicist Michael Faraday determined that the same amount of charge is needed to deposit one mole of any element or ion of valence one (meaning that each molecule of the ion has either one too many or one too few electrons). This amount of charge, equal to about 96.4853 kilocoulombs, became known as Faraday’s constant. Later, it was adopted as a convenient unit for measuring the charges used in electrolysis. One faraday is equal to the product of Avogadro’s number and the charge (1 e) on a single electron.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Claude-Servais-Mathias Pouillet

Claude-Servais-Mathias Pouillet was a French physicist who designed the sine galvanometer and the tangent galvanometer and used them to support Ohm’s Law. Claude-Servais-Mathias Pouillet was born in Cuzance, Doubs, France, on February 16, 1790. Pouillet was a French physicist. He supported the work of Ohm and confirmed Ohm’s Law in 1834.

Pouillet designed the sine galvanometer and the tangent galvanometer. The sine galvanometer is similar in appearance to the tangent galvanometer, but has provision to rotate the coil about a vertical axis. One rotates the coil from the magnetic meridian position until it coincides with the vertical plane containing the deflected needle. The current is then proportional to the sine of the angle of rotation. It is more sensitive than the tangent galvanometer and allows the use of a larger needle.

Pouillet’s sine galvanometer

The sine galvanometer, first described by Prof. Claude Pouillet of Paris in 1837, is a precursor of the tangent galvanometer. Like the tangent galvanometer, the sine galvanometer has a coil of wire carrying the current to be measured, and a magnetic compass needle in the middle of the coil. The coil of wire is first oriented in the magnetic north-south direction and the compass needle is acted on only by the horizontal component of the magnetic field of the earth.

The passage of the current sets up a magnetic field perpendicular to the coil, and the compass needle points in the direction of the total magnetic field. The coil is now rotated through an angle &o until the plane of the coil coincides with the needle. Under these conditions, the two torques acting on the needle are due to (a) the magnetic field B of the coil, which is at right angles to the coil, and (b) the component of the earth’s magnetic field perpendicular to the coil: BXsin&o. These two torques just balance each other. Since the value of B is proportional to the current I setting up this field, I is proportional to sin&o. The advantage of this apparatus is that the needle does not have to lie in a uniform magnetic field, and so the compass needle can be relatively large.

Pouillet’s tangent galvanometer

The tangent galvanometer was first described in an 1837 paper by Claude-Servais-Mathias Pouillet, who later employed this sensitive form of galvanometer to verify Ohm’s law. To use the galvanometer, it is first set up on a level surface and the coil aligned with the magnetic north-south direction. This means that the compass needle at the middle of the coil is parallel with the plane of the coil when it carries no current. The current to be measured is now sent through the coil, and produces a magnetic field, perpendicular to the plane of the coil, and directly proportional to the current.

The magnitude of the magnetic field produced by the coil is B; the magnitude of the horizontal component the earth’s magnetic field is B’. The compass needle aligns itself along the vector sum of B and B’ after rotating through an angle O from its original orientation. The vector diagram shows that tanO = B/B’. Since the magnetic field of the earth is constant, and B depends directly on the current, the current is thus proportional to the tangent of the angle through which the needle has turned.

Between 1837 and 1838 he made, independently of John Frederick William Herschel (1792-1871), the first quantitative measurements of the heat emitted by the Sun. His value was circa half the actual one because the level of the atmospheric absorption was uncertain those times, and the problem wasn’t solved until 1888 and 1904. With the Dulong-Petit law he wrongly estimated the temperature of the Sun’s surface to be around 1800 degreeC. This value was corrected in 1879 to 5430 degree C by Joef Stefan (1835-1893).

Pouillet’s pyrrhometer

Water is contained in the cylindrical container a, with the sun-facing side b painted black. The thermometer d is shielded from the Sun by the contained, and the circular plate e is used to align the instrument by ensuring that the container’s shadow is entirely projected upon it. [Reproduced from A.C. Young’s The Sun (revised edition, 1897). Although various scientists had attempted to calculate the Sun’s energy output, the first attempts at a direct measurement were carried out independently and more or less simultaneously by the French physicist Claude Pouillet and British astronomer John Herschel (1792-1871).

Although they each designed different apparatus, the underlying principles were the same: a known mass of water is exposed to sunlight for a fixed period of time, and the accompanying rise in temperature recorded with a thermometer. The energy input rate from sunlight is then readily calculated, knowing the heat capacity of water. Their inferred value for the solar constant was about half the accepted modern value of 1367+4 Watt per square meter, because they failed to account for of absorption by the Earth’s atmosphere.

Poillet works include On atmospheric electricity, (London 1832), Elements de physique experimentale et de meteorologie, (Paris 1856).

Poillet also studied physics of gases. The picture shows a Pouillet’s device for showing that vapour pressure increases under its degree of saturation.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Dominique François Jean Arago

Dominique Francois Jean Arago is known for his contributions to physics and astronomy. In physics, his principle work was in electromagnetism and in light. In 1820 he found that iron placed in a wire coil could be magnetized by the passage of current from either a Leyden jar or a voltaic cell. Seems that Arago was the first man to build consciounsly an electromagnet in September 1820.

In 1824 he discovered the phenomenon of magnetic rotation, in which a rotating copper disk deflects a magnetic needle suspended above it. Arago’s research in light commenced with his discovery of chromatic polarization in 1811. As an astronomer, Arago is remembered as the discoverer of the solar chromosphere and for his accurate measurements of the diameters of the planets.

Dominique Francois Jean Arago was born at Estagel a small village near Perpignan, in the d”partement of Pyrenees-Orientales, France, on February 26, 1786. He was the eldest of four brothers (three other brothers: Jean, Jacques, and Etienne). Jean Arago (1788-1836) emigrated to North America and became a general in the Mexican army. Jacques Etienne Victor Arago (1799-1855) took part in de Freycinet’s exploring voyage in the Uranie from 1817 to 1821, and on his return to France devoted himself to his journalism and the drama. The fourth brother, Etienne Vincent de Arago (1802-1892), is said to have collaborated with Honore de Balzac in The Heiress of Birague, and from 1822 to 1847 wrote a great number of dramatic pieces, mostly in collaboration.

Native house of Arago in Estagell

Arago was educated first at Perpignan, then at the Ecole Polytechnique (Polytechnic school) in Paris. It is known from his autobiography that even the professors in the Polytechnic school were very distinguished, they were remarkably incapable of imparting their knowledge or maintaining discipline. In 1804 Arago upon recommendation of Simeon Poisson was made secretary to the observatory at Paris.

Then from 1806 to 1809 Arago was in Spain, where he accompanied Jean Baptiste Biot on a measurement of an arc of meridian of the Earth which led to the standardisation of the metric system of lengths. On his return to Paris in 1809 he was elected to the Acad”mie des Sciences and received the chair of analytical geometry at the Ecole Polytechnique, Paris, where, at the age of 23, he succeeded Gaspard Monge. In 1830 he succeeded J.B.J. Fourier as the permanent secretary of the Ecole Polytechnique. He also was director of the Paris Observatory. He enjoyed a marked success as a lecturer.

He gave popular lectures on astronomy, which were both lucid and accurate – a combination of qualities which was rarer then than now. He reorganized the national observatory, the management of which has long been inefficient, but in doing this his want of tact and courtesy raised many unnecessary difficulties. Arago worked in a number of branches of physics.

Francois Arago

His first investigations concerned the polarization of light and in 1811 he discovered chromatic polarization. Working with Fresnel he discovered that two beams of light polarised in perpendicular directions do not interfere, leading to the transverse theory of light waves. Thus, Arago supported A.-J. Fresnel’s wave theory of light against the emission theory favoured by P.-S. Laplace, J.-B. Biot, and S.-D. Poisson.

According to the wave theory, light should be retarded as it passes from a rarer to a denser medium; according to the emission theory, it should be accelerated. Arago’s test for comparing the velocity of light in air and in water or glass was described in 1838, but the experiment required such elaborate preparation that Arago was not ready to perform until 1850, when his sight failed. Before his death, however, the retardation of light in denser media was demonstrated by A.-H.-L. Fizeau and L”on Foucault, who used his method with improvements in detail. This was the triumph of the wave theory of light.

In 1820, elaborating on the work of H.C. Orsted of Denmark, Arago showed that the passage of an electric current through a cylindrical spiral of copper wire caused it to attract iron filings as if it were a magnet and that the filings fell off when the current ceased. Seems that Arago was the first man to build consciounsly an electromagnet, in September 1820, in the same time he noticed that rhe iron became a magnet only during the flow of current, the effect finished when the current stopped: the basis of Morse telegraph.

Arago had also discovered, in 1824, that a disk of non-magnetic metal had the power of bringing a vibrating magnetic needle suspended over it rapidly to rest; and that on causing the disk to rotate the magnetic needle rotated along with it. When both were quiescent, there was not the slightest measurable attraction or repulsion exerted between the needle and the disk; still when in motion the disk was competent to drag after it, not only a light needle, but a heavy magnet.

The question had been probed and investigated with admirable skill both by Arago and Ampere, and Poisson had published a theoretic memoir on the subject; but no cause could be assigned for so extraordinary an action. It had also been examined by two celebrated men, Mr. Babbage and Sir John Herschel; but it still remained a mystery. Faraday saw mentally the rotating disk, under the operation of the magnet, flooded with his induced currents, and from the known laws of interaction between currents and magnets he hoped to deduce the motion observed by Arago. Faraday later proved these to be induction phenomena.

Arago’s Disk

In this device, a copper disk is rotated rapidly with a hand crank and a step-up pulley system. Balanced on a pivot above the center of the disk is a compass needle. The motion of the needle relative to the highly conducting copper disk induces eddy currents in the disk.

In turn, these eddy currents produce a torque on the magnetic needle, which starts to rotate. The presence of eddy currents may be inferred from the fact that a copper disk with radial slots cut in it produces little effect; the slots interrupt the eddy currents. The inverse effect also occurs: a spinning bar magnet will cause a suspended copper disk to rotate.

“Some years before Faraday discovered the principles of induced emf’s, Arago made a discovery which was not understood at the time. A horizontal disk of copper was mounted so that it could be set in rotation about a vertical axis. If a horizontal bar magnet was suspended over this disk, the bar wouldbe set in rotation in whichever direction the copper was turning. By some unseen force the magnet was dragged around by the moving plate. …It was not until after the discovery of induced emf’s that Arago’s experiment was understood.” From Physics, Third Edition, by O.M. Stewart, Ginn, 1939.

Observatoire de Paris

Coupole Arago

In astronomy, Arago discovered the Sun’s chromosphere and made accurate measurements of the diameters of the planets. However, Arago is best known for his part in the dispute between U.-J.-J. Le Verrier, who was his prot”g”, and the English astronomer John C. Adams over priority in discovering the planet Neptune and over the naming of the planet. Arago had suggested in 1845 that his student Le Verrier investigate anomalies in the motion of Uranus. When the investigation resulted in Le Verrier’s discovery of Neptune, Arago proposed that the newly found planet be named for Le Verrier.

In Paris you can still see ‘Arago’ markers: the line of 135 little bronze disks set out along the M”ridien de Paris – which is the world’s old zero longitude, but is now 2degree20’14” east of the new zero at Greenwich, set in 1884. France and Ireland didn’t adopt the new ‘zero’ until 1911. The disks are about 10 to 15 centimetres in diametre. Besides the name ‘Arago’ in raised engraving on them, there are also an ‘N’ and a ‘S.’

Arago’s portraits

Engraving by H.I. Torlet

Engraving by Charles Phillipe Auguste Carey, 1824-1897

Lithograph by Francois-Seraphin Delpech, 1778-1825, from the original engraving of Maguire

Printed by Alexandre Vincent Sixdeniers, 1795-1846, from the original engraving Nicolas-Eustache Maurin, 1799-1850.

Printed by Francois-Seraphin Delpech, 1778-1825, from the original engraving by Antoine Maurin, 1793-1860.

Arago played a rather dubious role in the history of photography: he championed the system of his friend, Daguerre, and apparently used his influence to persuade Hippolyte Bayard, another inventor who actually exhibited earlier than Daguerre, to keep his process secret so that the French Academy bought the rights to Daguerre’s invention.

Political career of Arago started in 1830 when he was elected deputy from Pyr”n”es-Orientales and later from Paris. Known for his republican views, Arago became a member of the provisional government formed after the Revolution of 1848. As minister of war and navy, he appointed greatest advocate of ending slavery Victor Schoelcher as undersecretary for the navy, who prepared the famous decree that abolished slavery in the colonies. Arago was elected to the National Constituent Assembly and then to the Executive Power Commission on May 10, 1848. He became president of the commission as he obtained the majority of votes at election and was the eldest member.

Portrait of Francois Arago by Ary Scheffer

Arago was a good friend of Alexander von Humboldt and Delacroix, and corresponded with Prosper Merim”e. He remained to the end a consistent republican, and after the coup d'”tat of 1852, though half blind and dying, he resigned his post as astronomer rather than take the oath of allegiance. It is to the credit of Napoleon III that he gave directions that the old man should be in no way disturbed, and should be left free to say and do what he liked. However, soon after that, Arago died in Paris on October 2, 1853.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005

Leopoldo Nobili

Leopoldo Nobili was an Italian physicist who carried out early research into electrochemistry and thermoelectricity. He invented a thermopile used in measuring radiant heat, and the astatic galvanometer.

Nobili was born in Trassilico in 1784. After finishing military school “Genius” in Modena, Nobili became an artillery officer. He participated in the Napoleon campaign in Russia, in which he was honored with the orden of “Legion d’ Onore”. In 1825 Nobili invented the astatic galvanometer, fundamental instrument in the history of electromagnetism. In 1826 he developed together with Melloni a thermoelectrical battery. In 1832 Nobili was appointed as a professor of physics in the the Regal Museum of Physics and Natural History of Florence, where, in collaboration with Vincenzo Antinori (director of the Museum from 1829), he performed numerous experiments on electromagnetic induction recently discovered by Faraday.

Nobili also performed study in thermoelectricity and invented a thermopile used in measuring radiant heat. A thermopile is a device that allows detection of weak sources of infra-red radiation using the thermo-electric effect.The Danish physicist Oersted and the French physicist Fourier invented the first thermo-electric pile in circa 1823 by working with pairs of small antimony and bismuth bars welded in series.

In 1829 Nobili designed a new instrument for the measurement of thermic radiations, a sort of “electric thermometre” that, following improvements by Melloni, accounted for a crucial technological innovation that allowed for a correct theoretical interpretation of thermic radiation. The new device consisted of a thermopile connected in series to the clips of the astatic galvanometer, which was also created by Nobili. He called it thermomultiplier or electric thermoscope. For most of the 19th century the thermomultiplier proved to be an irreplaceable instrument in the study of thermic radiation for its high reactivity and quickness.

This figure shows an original sketch of such an instrument after N. Nobili (1835). Due to the large thermal masses it was very slow in following signal changes. As can be imagined, these instruments were originally only applicable for laboratory work. In series connected thermocouples made of antimony and bismuth (a) form a thermopile (b). After N. Nobili (1835).

Nobili’s thermopile

This instrument is signed by the Neapolitan mechanician Filippo De Palma.

A brass base and a brass stem, the height of which could be adjusted through a ring screw locking nut, support the pile, which is inside a brass box with two binding posts at each side, which are fitted into two insulating bone sheets; at the top of it there are locking screw nuts that allow for the fixing (both in the front and in the back) of the brass thermic radiation collectors. The thermopile is made up of 30 pairs of thin sheets of different metal, most likely constantan copper. They are parallel and connected in series through weldings at their ends, so that all the even (upper) order weldings are on one extremity and all the uneven (lower) order weldings are on the other extremity.

The series of sheets, which are dipped into an insulating putty, form a small parallelepiped enclosed in a brass case. The two plain faces are uncovered and they are respectively obtained by the alignment of the even ordered and of the uneven ordered weldings. The ends of the weldings are linked to the terminal posts. A truncated cone brass collector with a door, which is also a good screen against possible secondary external sources, conveys the “radiant heat” to the even ordered surface. The other surface is enclosed in a second (smaller) box-shaped collector with a door.

The truncated-cone collector is placed in front of the heat source to be measured and the rheofores of the astatic galvanometer are connected to the terminal posts of the thermomultiplier. If the heat radiation of the source is of low intensity one can find an approximate direct proportionality between the degrees of the angular deflection of the galvanometer’s needle and the difference in temperature between the opposite weldings of the pile. If the heat radiation is more intense the proportion is more complex. In the second half of the 19th century the makers often provided each multiplier with a table, on which the intensity was expressed in degrees, indicating the existing relation between needle deflection and the constant intensity of thermic radiation.

However, the most important his contribution to electrical science was an astatic galvanometer. The first galvanometers, called simple galvanometers, were not shielded from terrestrial magnetic field, so when the electric current was running inside, on their needle there were the effects of two magnetic fields: the magnetic field produced by instrument’s electromagnet and the terrestrial one. That was obviously involving an error in measure.

Leopoldo Nobili, the inventor of the precision galvanometer, provided the galvanometer with a system able to remove the perturbation produced by the terrestrial magnetic field using the so-called astatic system. This galvanometer uses a mobile magnet. The current to be measured runs through a fixed circuit and acts on the mobile magnet. The astatic system was an ingenious contrivance which increased the sensitivity of galvanometers by the combination of two effects: a more intense deviation power and a weakening of the opposing effect of the earth’s magnetic field.

The first astatic galvanometer was presented by Nobili in May, 1825 at the Italian Society of Science at Modena. With this model Nobili improved the precision of the galvanometer considerably and he definitely favoured the development of delicate scientific research particularly in the field of electrophysiology and thermoelectricity. Nobili, in 1827, using his newly refined galvanometer which corrected for the earth’s magnetic field, was the first to report measuring the current in a frog using any kind of an instrument. This galvanometer was also used to measure hydroelectric currents. It is important saying that at the epoch the astatic galvanometers built by Nobili were exceptional and innovative tools. The purchase of such a tool from the inventor represented a real “scientific investment” wanted by the School to keep up the pace with the new discoveries and with the new scientific instruments.

Nobili’s Astatic Galvanometers

(However, the astatic galvanometers shown here are quite different from the original prototype developed by Nobili in 1825.)

The design of the galvanometer is identical to that created by the physicist Leopoldo Nobili in 1828. This is, however, the “portable” model which is smaller, simplified and, therefore, easily handled and transported. The circular mahogany base of the galvanometer is provided in its lower part and in its inner part with a lead ring that increases the stability of the instrument. Brass foot screws at the base of the device allow for appropriate levelling.

Two small brass gudgeon-pins can be inserted into two holes at the base and two copper wire coils insulated by green silk are still wrapped around them. The gudgeon-pins act as binding posts. In the centre of the base there is a rectangular brass frame around which a coil of copper wire is wrapped. The coil is insulated by thin yellow ochre silk. In the upper part of the coil is a rhomb-shaped opening allowing for the insertion of the lower needle of the astatic system. Above the coil, horizontally, there is the silver-plated quadrant of the galvanometer with a similar rhomb-shaped opening and a graduated scale engraved upon two concentric circular rings and divided into four quadrants that are graduated from 0o to 90o.

The inner ring has thin marks for the division into degrees; the outer ring is graduated by a mark every 5 degrees. The points of the rhomboidal opening indicate the zero value on the scale, and they are placed parallel to the wires of the coil. Near one of the 90o markings, the quadrant is covered by an ivory peg with a lower tooth that prevents the lower needle of the astatic system from oscillating beyond a certain limit and the thread from entangling. A brass knob on the side of the base permits of setting the coil and the quadrant making them rotate in relation to the mobile equipment without moving the whole instrument. This can be carried out by means of an inner rack and pinion mechanism.

A glass cylindrical bell, which is blocked by brass frames at its base, protects the instrument from external disturbances. The suspension mechanism of the mobile equipment can be vertically adjusted by rotating a small brass sphere linked to the external top of the bell. This instrument lacks the astatic system. By moving the brass knob, the scale can be adjusted so that the zero values correspond to the directions of the earth’s magnetic field. When inserted in series connection to an electrical circuit, the device gives a direct proportion (for slight deviation of the needle: up to 25o) between the angle and the intensity of the current.

Instruments of Nobili’s “Electromagnetic Box”

These instruments were part of a box of didactic and scientific instruments and models (called the electromagnetic box) created by Leopoldo Nobili to reproduce the main experiences of electromagnetism that were known at that time. The box, which is one of the most complete of the period, originally contained sixteen pieces; it was later enriched with additional models and instruments such as, for example, those suggested by Faraday or by Nobili himself (magnetic radiation). Unfortunately, only these four models of the original box now remain. They were listed in a catalogue of 1864, where “Firenze 1847” is written in the margin to indicate the place of origin and the date of entry.

Nobili’s electrochromic art

In 1826 Leopoldo Nobili obtained colors of interference on metallic surfaces through electrochemical oxidation. He studied the colored surfaces and the technique to obtain them not only for scientific reasons, but also for “the advantages that these colors and new technique of coloring metals may lend to the arts”. Nobili’s work can be considered an is example of generative art.


Tags: , , Filled Under: Biographies Posted on: December 1, 2005