Lives of the electricians

by William T. Jeans

However, Professor Wheatstone, having once taken in hand the production of electricity by an improved method, worked at the problem until he solved it. The electrical invention that ranks next in importance to the telegraph is the dynamo machine, and this also he had a share in introducing and improving. Its first conception has been claimed by different electricians. On the 4th of February, 1867, two papers were read before the Royal Society, one by Sir William Siemens, “On the conversion of dynamic into electrical force without the use of permanent magnetism,” and the other by Professor Wheatstone, “On the augmentation of the power of a magnet by the reaction thereon of currents induced by the magnet itself.” Both papers described the same discovery—the dynamo machine. The instrument described by Professor Wheatstone was made of a strip of soft iron, the core, fifteen inches long, bent in the form of a horse-shoe, and wound round in the direction of its breadth by 640 feet of insulated copper wire (covered with silk). The keeper or armature (the piece of iron extending across the ends of the horse shoe magnet) was hollow at two sides for the reception of eighty feet of insulated wire coiled lengthwise. The two wires being connected so as to form a single circuit, and the armature made to rotate in the opposite direction to that of the hands of a watch, powerful electrical effects were produced. The electricity generated by this motion of the armature soon made four inches of platinum wire red-hot, and decomposed water. These effects were thus explained by Professor Wheatstone: The electro-magnet always retains a slight residual magnetism, so is always in the condition of a weak permanent magnet; the motion of the armature occasions feeble currents in its coils in alternate directions, which, brought into the same direction, pass into the coil of the horse-shoe electro-magnet in such a manner as to increase the magnetism of the iron core; the strength of the magnet being thus increased, it produces in its turn stronger currents in the coil of the armature; and this alternate increase goes on until it reaches a maximum dependent on the rapidity of the motion and the capacity of the magnet.

Sir William Siemens, whose paper was sent in ten days before Professor Wheatstone’s, described a similar machine, but that they were independent discoveries has never been questioned. It was almost inevitable, however, that the question of priority should be discussed. Mr. Robert Sabine, who defended the rights of Professor Wheatstone, stated in 1877 that the time when “the idea of making a machine which would work into itself occurred to Professor Wheatstone, it is of course after his death impossible to determine, unless some manuscript notes should turn out in evidence. I am also unable to ascertain when the first experimental apparatus was made and tried. We must therefore start from the later stage, viz., the finished machine which was exhibited at the Royal Society in February, 1867.” It is interesting, however, to go a few years further back, and to find that the idea of producing powerful electrical effects by mechanical means was present in the mind of Professor Wheatstone a quarter of a century before it was announced as an accomplished fact. Early in 1843 he showed Professor A. De La Rive his new electro-magnetic telegraph; and in publishing an account of it the French Professor said that he (Wheatstone) “has endeavoured to apply the same principle to the production of a useful mechanical force; but he does not seem to me to have completely succeeded on this point; and I am convinced that a long period must yet elapse before steam is in this respect dethroned by electricity.”

Now it is a remarkable fact that at that very time there was a plan of a dynamo in MS., which unfortunately did not attract attention till thirty years afterwards. Dr. Gloesener, professor of physics at Liège University, in an extant MS. which was dated 20th of April, 1842, and which remained in the custody of public bodies in Belgium from that date, described electro-magneto oscillating and rotatory motors which he designed, and which he spoke of “as destined to take the place of steam and other motors.” In honour of this inventor, who died unrewarded for his prescience, the Electrical Congress at Paris admitted his daughter as their only lady member. However, Professor Wheatstone did not announce the practical realisation of his idea till February, 1867. “The machines then exhibited,” continues Mr. R. Sabine, “were made for Professor Wheatstone by Mr. Stroh in the months of July and August, 1866. When they were finished, tried, and approved of, they were in the usual course of business charged for by Mr. Stroh on the 12th of September, 1866. Mr. S. A. Varley says his machine (as it was exhibited at the Loan Collection) was completed and tried at the end of September or the beginning of October, 1866. Sir William Siemens says that his brother tried his first experimental machine in December, 1866. It is clear therefore that Professor Wheatstone’s machines—those exhibited at the Royal Society—were completed, tried, and charged for, before the first experimental machines of Sir W. Siemens or Mr. Varley were finished or ready for trial. The date when the undefined idea of making any machine first occurred to an inventor is of very little comparative importance, unless the idea be productive of some evidence of its existence, without which one would, I think, be inclined to suspect that memory might after a lapse of years be a little treacherous. Who had the first happy inspiration of a reaction machine we can scarcely expect to know now. Of its fruits we have better evidence, and I venture to think that the claims of the three inventors in question stand thus:

“Professor Wheatstone was the first to complete and try the reaction machine.

“Mr. S. A. Varley was the first to put the machine officially on record in a provisional specification, dated 24th of December, 1866, which was therefore not published till July, 1867.

“Dr. Werner Siemens was the first to call public attention to the machine in a paper read before the Berlin Academy on the 17th of January, 1867.”

In such cases the date of publication is generally regarded as the date of discovery; but whoever was the first inventor of the dynamo, it is now admitted that Professor Wheatstone’s machine was the most complete. After explaining how the rotation of the armature generated currents of electricity in the magnet, he stated that “a very remarkable increase of all the effects, accompanied by a diminution in the resistance of the machine, is observed when a cross wire is placed so as to divert a great portion of the current from the electro-magnet. Four inches of platinum wire, instead of flashing into redness and then disappearing, remain permanently ignited; the inductorium wire, which before gave no spark, now gave one of a quarter of an inch in length; and other effects were similarly increased.” Strange to say this discovery, announced in 1867, lay dormant till 1880, and then it was utilised by Sir William Siemens so as to obviate the great fluctuations previously experienced in electric-arc lighting. Till then the electric light often flickered instead of shining steadily, and the cause of its irregularity puzzled the electricians. In 1880 Sir William Siemens gave Professor Wheatstone full credit for having suggested a remedy for this defect in 1867.

Such an array of electrical inventions and discoveries was surely enough for one man; but electricity was only one of the many subjects that engaged his attention or exercised his ingenuity. Having traced the progress of his electrical inventions over a period of forty years, we must now collect some of the fruits of his labour in other sciences during that period. After his initial success with the electric telegraph in 1837, he began to publish in the following year his Contributions to the Physiology of Vision, in which he gave the results of experiments showing “that there is a seeming difference in the appearance of objects when seen with two eyes, and when only one eye is employed; and that the most vivid belief in the solidity of an object of three dimensions arises from two perspective projections of it being simultaneously presented to the mind.” At the same time he gave a description of his newly-invented instrument for illustrating these phenomena—the stereoscope, which was first announced in 1838, and was improved in course of the next fourteen years.

When he described the stereoscope to the British Association in 1838 and explained the scientific principle which it illustrated, Sir David Brewster said he was afraid that the members could scarcely judge—from the very brief and modest account given by Professor Wheatstone of the principle and of the instrument devised for illustrating it—of its extreme beauty and generality. He (Sir David) considered it one of the most valuable optical papers which had been presented to the Association. He observed that when taken in conjunction with the law of visible direction in binocular vision, it explained all those phenomena of vision by which philosophers had been so long perplexed; and that vision in three dimensions received the most complete explanation from Professor Wheatstone’s researches. At the same time Sir John Herschel characterised Professor Wheatstone’s discovery as one of the most curious and beautiful for its simplicity in the entire range of experimental optics.

At the date of the publication of his experiments on binocular vision, said Professor Wheatstone, the brilliant photographic discoveries of Talbot, Niepce, and Daguerre had not been announced to the world, as illustrating the phenomena of the stereoscope. He could therefore at that time only employ drawings made by the hands of the artists. “Mere outline figures, or even shade perspective drawings of simple objects, did not present much difficulty; but it is evidently impossible,” he says, “for the most accurate and accomplished artist to delineate by the sole aid of his eye the two projections necessary to form the stereoscopic relief of objects as they exist in nature with their delicate differences of outline, light, and shade. What the hand of the artist was unable to accomplish, the chemical action of light, directed by the camera, is enabled to effect. It was at the beginning of 1839, about six months after the appearance of my memoir in the Philosophical Transactions, that the photographic art became known, and soon after, at my request, Mr. Talbot, the inventor, and Mr. Collen (one of the first cultivators of the art) obligingly prepared for me stereoscopic Talbotypes of full-sized statues, buildings, and even portraits of living persons. M. Quetelet, to whom I communicated this application and sent specimens, made mention of it in the Bulletins of the Brussels Academy of October 1841. To M. Fizeau and M. Claudet I was indebted for the first daguerreotypes executed for the stereoscope.”