FOOTNOTES:
[7] The keeper or armature is the piece of iron which is placed across the ends or poles of a horseshoe magnet.
CHAPTER IV.
“A name, even in the most commercial nation, is one of the few things which cannot be bought. It is the free gift of mankind, which must be deserved before it will be granted, and is at last unwillingly bestowed. But this unwillingness only increases desire in him who believes his merit sufficient to overcome it.”—Dr. Johnson.
From the two preceding chapters it appears that Professor Wheatstone was not only the inventor of the first electric telegraph used in England, but that he at last invented the most perfect transmitter of telegraphic intelligence. He not only nursed it from its birth, but reared it to maturity; and the period that elapsed between his first and last invention of telegraphic apparatus was exactly twenty-one years. But this was not enough for his versatile mind to accomplish. He had worked successfully as an inventor for seventeen years before his first telegraph was invented, and he continued to work at his favourite subjects for seventeen years after his last great telegraphic invention. Having confined our attention in the last two chapters almost exclusively to the progress of the telegraph, it remains for us to follow the inventor into the bye-paths which he now and then delighted to tread, as well as to follow his course during his latter years along the highway of electrical science in which his genius appeared to find its most congenial exercise.
It has already been explained that in the early years of his electrical researches, he was one of the first men in England to draw attention to the thermo-electric pile originally constructed by Nobili and Melloni in 1831; it consisted of a bundle or pile of small plates of bismuth and antimony, which when heated converts heat into electricity. By connecting this pile by coils of wire with a galvanometer (a movable needle) it becomes a delicate means of indicating minute changes of temperature, the electricity generated by heat moving the needle. This instrument can be affected by the warmth of the hand held several yards away from it; and it is believed that without it, as a thermoscope, the important discoveries respecting radiant heat made by Professor Tyndall and others would have been impossible. It has even been found possible by means of this sensitive apparatus to estimate the amount of radiant heat emitted by insects. In 1837 Professor Wheatstone predicted great results from the thermo-electric pile as a source of electricity, and in 1865 he constructed a powerful thermo-electric battery of that description. It was composed of sixty pairs of small bars, and it was stated that by its action “a brilliant spark was obtained, and about half an inch of fine platinum wire when interposed was raised to incandescence and fused; water was decomposed, and a penny electro-plated with silver in a few seconds; whilst an electro-magnet was made to lift upwards of a hundredweight and a half.” This thermo-electric battery may be said to have electrified the imaginations of men of science, who saw visions and dreamt dreams about its future. For instance, it was suggested that “like windmills, thermo-electric batteries might be erected all over the country for the purpose of converting into mechanical force, and thus into money, gleams of sunshine which would be to them as wind to the sails of a mill.” Many other attempts have been made to construct a thermo-electric pile capable of being used as a generator of electricity instead of the voltaic battery or the dynamo; and although much progress was made in later years, the difficulty in the way, as Lord Rayleigh observed in 1885, was the too free passage of heat by ordinary conduction from the hot to the cold junction.
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.”
As indicating the relations that continued to exist between him and Sir David Brewster on the subject of vision, it is worthy of remark that in 1844 Professor Wheatstone brought before the British Association some singular effects produced by certain colours in juxtaposition. Observing that a carpet of small pattern in green and red appeared in the gas-light as if all the parts of the pattern were in motion, he had several patterns worked in various contrasted colours in order to verify and study the phenomena. Both he and Sir David Brewster brought to York separate communications on this subject, and specimens of coloured rugwork to illustrate it; but on seeing Professor Wheatstone’s specimens, Sir David withheld both his paper and his illustrations, and simply made a few remarks on Wheatstone’s paper, stating that when he came to York he did not know that the phenomena were produced by any other colours but red and green, and that he was indebted to Professor Wheatstone for showing him that red and blue had the same effect. The Professor accounted for it by saying that the eye retained its sensibility for various colours during various lengths of time.
In the stereoscope designed by Professor Wheatstone mirrors were used instead of lenses; and though the effect produced by mirrors was similar to that which we now see by means of lenses, its startling novelty did not excite popular interest. Indeed it was only used by two or three Professors to illustrate optical phenomena; and with that exception it might be said to have been unhonoured and unused for several years. It was Sir David Brewster who proposed to use lenses instead of mirrors, and thus gave to it the form in which it eventually became popular; but even then its popularity might be described as of foreign origin. In addressing the British Association in 1848 on the theory of vision, Sir David Brewster said that the solution of some problems that had long baffled opticians was greatly facilitated by that beautiful instrument, the stereoscope of Professor Wheatstone. Next year Sir David exhibited his new form of the stereoscope before the British Association at Birmingham, and in 1850 he exhibited it at Paris, and explained it to M. Duboscq Soleil, an optician of that city, who was so impressed with its advantages that he began to manufacture it, and to call public attention to its powers. One was also exhibited before the French Academy of Sciences, who appointed a committee to examine it.
In 1849 Sir David Brewster offered his improvement in the stereoscope gratuitously to opticians in Birmingham and London; but they did not accept it; and it was only after it became an object of wonder in France that it began to be appreciated in England. At the Great Exhibition of 1851 M. Duboscq Soleil showed a beautiful instrument together with a fine set of binocular daguerreotypes; and another instrument by the same maker was presented by Sir David Brewster to the Queen. In the same year some were exhibited at one of the soirées of Lord Rosse, where they excited much interest. The attention of English photographers being then directed to it, photographic pictures and portraits began to be executed for it in abundance. The stereoscope soon came to be in demand; it was manufactured by English as well as French makers; and thus became a favourite ornament or scientific curiosity. During the next five years 500,000 stereoscopes were sold.
While Sir David Brewster did so much to make the stereoscope popular, Professor Wheatstone was generally accredited with the original invention. In 1849 the eminent French philosophers, MM. L. Foucault and J. Regnault, stated in the Comptes Rendus that “in a beautiful investigation on the vision of objects of three dimensions, Professor Wheatstone states that when two visual fields, or the corresponding elements of the two retinæ, simultaneously receive impressions from rays of different refrangibility, no perception of mixed colours is produced. The assertion of this able philosopher being opposed to the opinion of the majority of those who have attended to the same subject, we have thought it useful to repeat, modify, and extend these experiments; and the stereoscope of Professor Wheatstone offered a simple means of disentangling these delicate observations of all complication capable of injuriously affecting the accuracy of the physiological results.”
In an account of it published in London in 1851 it was truly stated that the phenomena of vision had engaged the attention of the most acute philosophers; and that the researches of Professor Wheatstone had done more than those of any other man to explain the result of single vision with a pair of eyes while under the influence of two impressions; for in his stereoscope two images drawn perspectively upon plane surfaces, when viewed at the angle of reflection appear to be converted into a solid body, and to convey to the mind an impression of length, breadth, and thickness. At the same time it was explained that Sir David Brewster modified the instrument and imitated the mechanical conditions of the eye by cutting a lens into halves, and placing each half so as to represent an eye with a distance of two and a half inches between them. Although it was this use of lenses that made the stereoscope fashionable, Professor Wheatstone continued to recommend his original reflecting instrument as the most efficient form, not only for investigating the phenomena of binocular vision, but also for exhibiting the greatest variety of stereoscopic effects, “as it admits of every required adjustment, and pictures of any size may be placed in it.”
But in 1856 the chorus of unanimity as to the original invention of the stereoscope was broken. Detraction then began. A book, which was published in that year, not only disputed the scientific accuracy of the principles of vision enunciated by Professor Wheatstone, but endeavoured to divest him of all credit in connection with the invention of the stereoscope. Who ever could have written such a book? Sir David Brewster! Nor did a book suffice. In 1860 he read a paper before the Photographic Society of Scotland “respecting the invention of the stereoscope in the sixteenth century and of binocular drawings by Jacopo da Empoli, a Florentine artist.” He stated that inquiry into the history of the stereoscope showed that its fundamental principle was known even to Euclid; that it was distinctly described by Galen 1500 years ago; and that Baptista Porta had, in 1599, given such a complete drawing of the two separate pictures as seen by each eye, and of the combined picture placed between them, that in it might be recognised not only the principle, but the construction of the stereoscope.
It is noteworthy that Sir David Brewster first gave Professor Wheatstone the credit of being the inventor of the telegraph, and afterwards ridiculed his claims.
As to the principle of the stereoscope, it was at the meeting of the British Association in 1848 that Sir David Brewster definitely disputed the theory of vision which ascribes to experience instead of intuition the correct perception of objects and of distances with two eyes as well as with one. He observed that an infant obtained his first glances of the external world by opening on it both eyes which evidently conveyed single vision to the mind; and in like manner he contended that young animals saw distances correctly almost at the instant of their birth. The duckling ran to the water almost as soon as it broke the shell; the young boa constrictor would involve and bite an object presented to it; and on the other hand no person ever saw a child use such motions as proved it to perceive objects at its eye, to grasp at the sun or moon or other inaccessible objects, but quite the contrary. Dr. Whewell entirely dissented from the views of Sir David Brewster, which were not new; and in confirmation of Dr. Whewell’s contention that experience was a necessary guide in the use of the senses, a Bristol oculist gave several instances of persons who on being restored to sight from total blindness could not at first form any idea of the distances, or directions, or shapes of bodies; in one instance the patient, for a length of time, was in the habit of shutting her eyes entirely and feeling the objects, in order to get rid of the confusion which vision gave rise to; and it was only as her experience grew more perfect that she saw with increasing correctness and pleasure, until at length her sight became perfect. The controversy on this subject has engaged the attention of many philosophers and has not yet been settled. In later years Helmholtz, who preferred the mirror stereoscope of Wheatstone to the lenticular one of Brewster on the ground that the former gave more sharply-defined effects, stated that the hypotheses successively formed by the various supporters of the intuitive theories of vision were quite unnecessary, as no fact had been discovered inconsistent with the empirical theory, which supposes nothing more than the well-known association between the impressions we receive and the conclusions we draw from them, according to the fundamental laws of daily experience.
In 1851 Professor Wheatstone invented the pseudoscope, an instrument which conveys to the mind false perceptions of all external objects, called conversions of relief, because the illusive appearance had the same relation to that of the real object as a cast to a mould or a mould to a cast. Thus a china vase ornamented with flowers in relief showed in the pseudoscope a vertical section of the interior with painted hollow impressions of the flowers. In like manner a bust became a deep hollow mask. When two objects at different distances were viewed through it, the most remote object appeared the nearest, while the nearest became the most remote. A flowering shrub in front of a hedge appeared in the pseudoscope as behind the hedge, and a tree standing outside a window was transferred to the inside of the room.
This instrument has been useful in illustrating mental phenomena according to the impressions it produces on observers. It is found that with most persons the inverted appearance that an object presents when seen through the instrument is alone seen at first; but after the real form of the object becomes known, their visual perception is so much under the control of their matter-of-fact experience that they are unable again to see the inversion of the object. With other observers the real appearance of the object lasts a shorter or longer time, after which their visual impressions predominate to such an extent that it again appears inverted.
Nor did his fertility in illustrating visual effects end here. Mr. J. Plateau stated in the journal of the Belgian Royal Academy for 1851 that Professor Wheatstone had communicated to him a plan for combining the principle of the stereoscope with that of the Phenakisticope, whereby figures simply painted upon paper would be seen both in relief and in motion, thus presenting all the appearances of life.
In 1851 he supplied the scientific world with a mechanical illustration of the earth’s rotatory motion which was much admired, and which set at rest some disputed points. Questions had been raised at that time as to the effect which the rotation of the earth had upon bodies which, like the pendulum, oscillated from fixed points; and M. Foucault designed mechanical means of showing such effects which were said to make the rotation of the earth as evident to the sight as that of a spinning-top. His original experiment was shown in Paris to M. Arago and other scientific men, and was described as follows:—To the centre of the dome of the Pantheon (272 feet high) a fine wire was attached, from which a sphere of metal, four or five inches in diameter, was suspended so as to hang near the floor of the building. This apparatus was put in vibration after the manner of a pendulum. Under, and concentrical with it, was placed a circular table, some twenty feet in diameter, the circumference of which was divided into degrees, minutes, &c., and the divisions were numbered. The elementary principles of mechanics showed that, supposing the earth to have the diurnal motion upon its axis which explains the phenomena of day and night, the plane in which the pendulum vibrated would not be affected by this diurnal motion, but would maintain strictly the same direction during twenty-four hours. In this interval, however, the table over which the pendulum was suspended would continually change its position in virtue of the diurnal motion, so as to make a complete revolution in about 30h. 40m. Since, then, the table thus revolved, and the pendulum which vibrated over it did not revolve, a line traced upon the table by a point or pencil projecting from the bottom of the ball would change its direction relatively to the table from minute to minute, and from hour to hour; so that when paper was spread upon the table, the pencil formed a system of lines radiating from the centre of the table; and the two lines thus drawn after the interval of one hour always formed an angle with each other of about eleven and a half degrees, being the twenty-fourth part of the circumference. This was actually shown to crowds who daily flocked to the Pantheon to witness this remarkable experiment. The practised eye of a correct observer, aided by a magnifying glass, could actually see the motion which the table had in common with the earth under the pendulum between two successive vibrations, it being apparent that the ball did not return precisely to the same point of the circumference of the table after two successive vibrations.
This experiment was repeated in other towns both on the Continent and in England with accordant results. It was pointed out, however, that the influence of the earth’s magnetism and other sources of error might produce discrepancies; but Professor Wheatstone invented an apparatus which presented a complete illustration not only of the general principle, but of the precise law of the sine of the latitude. He maintained the principle that so long as the axis of vibration continues parallel to itself, the arc of vibration will continue parallel to itself; but if the axis does not continue parallel, the direction of the arc of vibration will deviate. His apparatus illustrated that principle. Instead of a pendulum he used the vibrations of a coiling spring, the axis of which could be placed in any required inclination or latitude with respect to a vertical semicircular frame which revolved about its vertical axis: the direction of the vibration was seen to change in a degree proportioned to the sine of the latitude or inclination. He remarked, with reference to Foucault’s experiment, that the difficulty of the mechanical investigation of the subject, and the delicacy of an experiment liable to so many causes of error, had led many persons to doubt either the reality of the phenomena or the satisfactoriness of the explanation; and he therefore supplied an experimental proof which was not dependent upon the rotation of the earth. His experimental proof was pronounced the most complete and satisfactory that had been given.
Another subject that attracted his attention for years was the art of writing in cipher. When he was before a Parliamentary Committee in 1840 he was asked whether the telegraph was not open to the objection that the officials working it necessarily became acquainted with the contents of all the messages. His only reply to that objection then was that secret messages could be sent in cipher. In later years he constructed a machine for that purpose, intending to complete the benefits of the electric telegraph by rendering it possible to transmit telegraphic messages in a way that would render their contents unintelligible to the officials through whose hands they passed. This machine was called the cryptograph, and it periodically changed the characters representing the successive letters of the written communication, so that it could not be read except by the receiver, who, possessing a corresponding machine set in the same way as the sender’s, could by reversing the operation understand the characters. He stated that by the aid of this instrument an extensive secret correspondence could be carried on with several persons, and a separate cipher could be employed by each correspondent. The cipher despatches prepared by it were unintelligible to any person unacquainted with the word that might be selected as the basis of the cipher alphabet, and though any person might possess one of the instruments, he could not translate the cipher so long as the key-word was kept secret. Although this instrument has been scarcely known to the public, experience has proved its simplicity and efficiency; and it has been employed by the British Government, the French Government, and the English police.
Its principle is easily understood. Any word in which the same letter does not recur, may be selected as the key-word. Take the word “saucer,” and write under the separate letters of it, the remaining letters of the alphabet consecutively in the following columnar form:
In the machine are two movable spaces, one containing the letters of the alphabet in the usual order, and the other adapted to receive in juxtaposition the cipher letters which, with “saucer” as the key-word, would be the above letters arranged in a row, one column following another, thus:
A marvellous instance of his skill in deciphering cryptographic documents occurred in 1858. Sir Henry Ellis relates that a good many years previously the trustees of the British Museum purchased at a high price what appeared to be a very important document in cipher, occupying seven folio pages closely filled with numerals. The top of every page bore the signature of King Charles the First, and was countersigned by Digbye. For a long time Sir Henry Ellis endeavoured to get it deciphered for the purpose of including it in his series of letters illustrative of the history of England, but he could not get any one able to read it. One evening at Earl Stanhope’s he accidentally mentioned that fact to Lord Wrottesley, who suggested that Professor Wheatstone’s ingenuity might be able to unravel the secret writing, and accordingly Sir Henry Ellis at once sent it to the Professor, requesting that he would investigate its contents. This took place on June 1st, 1858. In the document in question about ninety different numerals were employed to represent the letters of the alphabet, and besides the complexity of each letter being represented by several distinct numerals, there was no division between the different words, and the numbers represented not English (as was at first supposed) but French words. This document, which had baffled all other experts, was interpreted by Professor Wheatstone. A copy of it having been sent two or three years afterwards to the Philobiblon Society, along with the key to the cipher, the Society expressed “their admiration of this additional instance of that wonderful faculty of interpretation which seems to ordinary minds a special intuition not unworthy of a great scientific discoverer and practical benefactor of the age.”
Among the subjects that engaged his attention both at the beginning and the close of his electrical studies was the construction of self-registering thermometers. In 1843 he invented a telegraphic thermometer, or rather an electro-magneto-meteorological register. It recorded the indications of the barometer, and the thermometer, and the psychrometer every half-hour, and printed the result in figures on a sheet of paper. The recording mechanism was a kind of clockwork, which was capable of registering 1000 observations in a week without any readjustment, and it could be prepared in five minutes for another week’s work. In consequence of this periodic winding up, the instrument could not be left for an indefinite time; and as there were many situations in which it was desirable to have meteorological indications, but to which access could not be obtained for long periods, he devised a new telegraphic thermometer whose indications were made visible at distant stations without the aid of clockwork. It consisted of two parts; one part, called the responder, contained a metallic thermometer consisting of a spiral ribbon of two dissimilar metals; this responder was connected by two telegraph wires with the other portion of the apparatus called the questioner, which recorded the changes of temperature by the movement of a hand on a dial round the edge of which was a thermometric scale. The responder could be placed at the top of a high mountain for any length of time, while its indications could be read at the station below; it could be placed deep down in the earth whose temperature could thus be ascertained over a long period; or it might be lowered to the bottom of the sea, and its indications read at intervals during its descent as well as periodically at the bottom, whereas previous marine thermometers required to be raised at every fresh observation.
In 1871 Mr. Spottiswoode delivered a lecture at the Royal Institution on “Some experiments on successive polarisation of light made by Sir Charles Wheatstone.” He explained that the experiments then described were made by Wheatstone some years previously, but the pressure of other avocations delayed their publication. Certain it is that the polarisation of light formed the subject of experiments twenty-five years previously, for in 1848 Professor Wheatstone described to the British Association an apparatus which by means of the polarisation of light indicated true solar time in places where a sun-dial would be useless. It was called Wheatstone’s polar clock or dial, and he described several forms of it.
It would be tedious to enumerate all his minor inventions; but it is worthy of observation that from first to last there was a remarkable periodicity in the production of his chief inventions. Beginning with his magic lyre in 1821, he invented the concertina in 1829,[8] and his first telegraph in 1837. Between 1837 and 1843 he produced eight inventions; and after that period his next notable inventions were his pseudoscope and his novel apparatus illustrating the rotation of the earth in 1851. In 1858 he produced his automatic transmitter, which was succeeded in 1867 by his dynamo. It thus appears that a period of eight years elapsed between each of these important inventions, with the single exception of the interval from 1837 to 1843, when he produced eight inventions. This periodic ripening of his fertile mind into a rich harvest of inventions extended over half a century. It need scarcely be matter of surprise, therefore, that when death put a stop to his labours on the eve of another cycle, he left evidences of fresh fruits which were not yet matured. His last invention was a new recording instrument for submarine cables. It consisted of a globe of mercury which a slight electrical impulse caused to move to and fro in a capillary tube containing acid, the movements of the globule to the right or left by the delicate current of a cable representing telegraphic signs. It was said at the time to be fifty-eight times more sensitive than any previous recorder.
“The catalogue of Wheatstone’s valuable labours,” says a friend of his, “is still far from being exhausted: but it must now suffice only to mention some of his unpublished and incomplete researches, of which many exist. At the early part of his career, when his thoughts were mainly directed to Acoustics, he endeavoured to investigate the causes of the differences of ‘timbre’ or quality of tone in different musical instruments, presuming it to depend on the nature of superposed secondary vibrations, and of the material by which they are affected. This the writer frequently, but in vain, urged him to complete and publish; but such was the fecundity of his imagination that he would frequently work steadily for a time at a given subject, and then entirely put it aside in pursuit, it may be, of some more important or more practical idea that had presented itself to his mind. A short treatise is in existence on the capabilities of his well-known wave-machine, in which rows of white balls, mounted on rods, are actuated in two directions perpendicular to each other by guides or templets with suitable curved outlines; by means of this machine many combinations of plane and helical waves may be demonstrated, and especially those related to the theory of polarised light.
“In furtherance of this subject he devised a new form or mode of geometrical analysis, to which he gave the title of Bifarial Algebra, in which both the magnitude and the relative position of lines on a plane surface are designed to be represented by the introduction of two new symbols to represent positive and negative perpendicular directions. The same principle has also been extended to three dimensions, with a further proposal of new symbols, under the name of Trifarial Algebra. On this subject a brief treatise exists in manuscript.
“Among the subjects of his more recent but still incomplete investigations in light and electricity, the following may be mentioned:—colours of transparent and opaque bodies; colours obtained by transmission and reflection; absorption-bands in coloured liquids; spectroscopic examination of light reflected from opaque and dichroic bodies; electro-motive forces of various combinations; inductive capacities of various bodies; experiments on electro-capillarity; and the construction of relays.”
“Although any one would be charmed by his able and lucid exposition of any scientific fact or principle in private, yet his attempt to repeat the same process in public invariably proved unsatisfactory. An anecdote may here be mentioned in confirmation of this peculiar idiosyncrasy. Wheatstone and the writer of this were for several years members of a small private debating society comprising several familiar names in science, art, or literature, that met periodically at one another’s houses to discuss some extemporaneous subject, and every member was expected to speak. Wheatstone never could be induced to open his lips, even on subjects on which he was brimful of information.”
His familiar form, says Mr. W. H. Preece, was well known to the old habitués of the Royal Institution. “Whenever either of his favourite subjects, light, sound, or electricity, was under discussion, his little, active, nervous, and intelligent form was present, eagerly listening to the lecturer. He was no lecturer himself, yet no one was more voluble in conversation. In explaining any object of his own invention, or any apparatus before him, no one was more apt, but when he appeared before an audience and became the focus of a thousand eyes, all his volubility fled; and left him without a particle of that peculiar quality which enables an individual with confidence to come before a critical audience, such as is represented by the members of the Royal Institution, to develop scientific facts or describe apparatus. This defect proved fortunate, for it was the cause of Wheatstone obtaining the aid of the greatest lecturer of the age; and the annals of that Institution bear record of many Friday evenings being occupied by Faraday in expounding the ‘beautiful developments,’ as he called them, of Wheatstone.... Though he was no lecturer, or prolific writer, he was an unrivalled conversationalist, and those who had the pleasure of his conversation could never forget the lucidity with which he explained his apparatus. His bibliographical knowledge was almost incredible. He seemed to know every book that was written and every fact recorded, and any one in doubt had only to go to Wheatstone to get what he wanted. The elegance of the design of everything Wheatstone accomplished must always maintain him in the very first rank of the wonderful geniuses of this wonderful century.”
Many honours and distinctions were conferred on him. He received the degrees of D.C.L. and LL.D. from the Universities of Oxford and Cambridge, and he was made a corresponding or honorary member of all the principal scientific academies in Europe. Of the thirty-four distinctions conferred on him by Governments, Universities, or learned Societies, eight were German, six French, five English, three Swiss, two Scotch, two Italian, two American, besides one Irish, Swedish, Russian, Belgian, Dutch, and Brazilian. Most of his honours were conferred in recognition of his electrical inventions. For these he was knighted in 1868; and both before and after that date he was more lavishly praised abroad than at home. In 1867, the President of the Italian Society of Sciences, in conferring on him the honour of honorary membership, said that the applications of the principle of the Rotating Mirror were so important and so various that this discovery must be considered as one of those which have most contributed in these latter times to the progress of experimental physics. “The memoir on the measure of electric currents and all questions which relate thereto and to the laws of Ohm has powerfully contributed to spread among physicists the knowledge of these facts and the mode of measuring them with an accuracy and simplicity which before we did not possess. All physicists know how many researches have since been undertaken with the rheostat and with the so-called ‘Wheatstone Bridge,’ and how usefully these instruments have been applied to the measurement of electric currents, of the resistance of circuits, and of electro-motive forces.”
In 1873 the French Society for the Encouragement of National Industry presented him with the great medal of Ampère which is awarded every six years for what is considered the most important application of science to industry. The former recipients of this medal were Henri St. Claire Deville, who introduced the manufacture of aluminium; Ferdinand De Lesseps, the engineer of the Suez Canal; and Boussingault, the distinguished agricultural chemist. Of Sir Charles Wheatstone, the Committee of Economic Arts said: “While his kaleidophone has been the point of departure in a method which permits sound to be studied by the aid of the eye; while his researches on the qualities of sound and on the production of vowels, as well as the creation of his speaking machine have realised many points in the theory of the voice; while his ingenious apparatus illustrating the propagation and the combination of waves has facilitated the understanding of these delicate phenomena and contributed to throw light on the mechanism of undulatory motion, his numerous researches on the application of electricity, in which he has shown both profound science and a genius marvellously inspired, occupy a great place in the history of the electric telegraph. It was he who first realised, under conditions really practicable, this admirable means of communication between men and between nations, and we ought not to forget that more than once he has come personally among us to prepare its organisation and promote its success. The unanimous choice made by the Committee of the Economic Arts, and cordially ratified by the Council, honours our society as much as him who is the object of it. We hope to give on this occasion a testimony of sympathy with a nation in which science is held in such high esteem. In conferring on Sir Charles Wheatstone a reward rendered valuable by those who have already received it, the Council performs a pure act of justice, and acquits, at least for some among us, a debt of gratitude.”
For many years he was a corresponding member of the French Academy of Sciences, and on June 30, 1873, he was elected a Foreign Associate in succession to Baron Liebig, deceased, and his election to this position, the highest honour which it was in the power of that body to bestow upon “a foreigner,” was almost unanimous.
While the highest honours that Science could bestow were thus being conferred on him, he was seized with inflammation of the chest, from which he died at Paris on October 19, 1875. His remains were removed to London and interred in Kensal Green Cemetery. Prior to the removal of his body from Paris, a religious service was held at the Anglican chapel, at which a deputation from the Academy attended, and MM. Dumas and Tresca delivered addresses. M. Dumas said: “To render to genius the homage which is its due, without regard to country or origin, is to honour one’s self. The Paris Academy of Sciences, always sympathising with English science, did not hesitate, during the troubled time of the wars of the Empire, to decree a grand prix to Sir Humphry Davy. Now in a time of peace it comes to fulfil with grief a duty of affection to one of his noblest successors, by gathering round his coffin to offer him a last homage. A foreign Associate of the Academy of Sciences, exercising by a rare privilege in virtue of that title all the rights of its members during his life, we are bound to render to his mortal remains the same tribute which we render to fellow-countrymen who are our colleagues. The memory of Sir Charles Wheatstone will live among us not only for his discoveries and for the methods of investigation with which he has endowed science; but also by the recollection of his rare qualities of heart, the uprightness of his character, and the agreeable charm of his personal demeanour.”
The President of the Society of Telegraph Engineers, Mr. Latimer Clark, in announcing his death, said: “If you wish correctly to estimate the magnitude of a building, it is necessary to place yourself at a distance from it; it is only then you can fully realise its real proportions as compared with its fellows. So it is with the name of Sir Charles Wheatstone. I feel that in order to appreciate how great a man he has been we must look forward many years—I mean by that a very great many years—if we can take our stand in imagination a thousand years hence, the name of Wheatstone will still be well known and highly honoured. So far as we can judge from the history of the human race and of the past, I am of opinion that, as long as history lasts, the name of Wheatstone will be associated with that of Watt and Stephenson as men who, in the era of Queen Victoria, were prominent in the introduction of those magnificent enterprises by which the whole world has been practically reduced to one-twentieth part of its former size. Our successors will hear in their day of the giants of the Victorian era; they will hear of Watt in connection with the steam-engine, and of Stephenson in connection with the locomotive and railways; and they will also hear of Wheatstone in connection with the electric telegraph. We who are closer to him, and know more of the history of the invention, are well aware that others are entitled to share with him in the fullest degree the honour of the introduction of the electric telegraph; but history is written very much by scientific men, and Sir Charles Wheatstone was himself an eminently scientific man, and mingled so much with scientific men, that those who will be the recorders of the history of the future will, to a great extent, associate his name alone with the practical introduction of the electric telegraph.”