One day a workman in Edison's laboratory caught up a crying child and held it over the phonograph. Here is the phonogram it made, and here in England we can listen to its wailing, for the phonograph reproduces every kind of sound, high or low, whistling, coughing, sneezing, or groaning. It gives the accent, the expression, and the modulation, so that one has to be careful how one speaks, and probably its use will help us to improve our utterance.

By speaking into the phonograph and reproducing the words, we are enabled for the first time to hear ourselves speak as others hear us; for the vibrations of the head are understood to mask the voice a little to our own ears. Moreover, by altering the speed of the barrel the voice can be altered, music can be executed in slow or quick time, however it is played, inaudible notes can be raised or lowered, as the case may be, to audibility. The phonograph will register notes as low as ten vibrations a second, whereas it is well known the lowest note audible to the human ear is sixteen vibrations a second. The instrument is equally capable of service and entertainment. It can be used as a stenograph, or shorthand-writer. A business man, for instance, can dictate his letters or instructions into it, and they can be copied out by his secretary.

Callers can leave a verbal message in the phonograph instead of a note.

An editor or journalist can dictate articles, which may be written out or composed by the printer, word by word, as they are spoken by the reproducer in his ears.

Correspondence can be carried on by phonograms, distant friends and lovers being able thus to hear each other's accents as though they were together, a result more conducive to harmony and good feeling than letter-writing. In matters of business and diplomacy the phonogram will teach its users to be brief, accurate, and honest in their speech; for the phonograph is a mechanical memory more faithful than the living one.

Its evidence may even be taken in a court of law in place of doc.u.ments, and it is conceivable that some important action might be settled by the voice of this DEUS EX MACHINA. Will it therefore add a new terror to modern life? Shall a visitor have to be careful what he says in a neighbour's house, in case his words are stored up in some concealed phonograph, just as his appearance may be registered by a detective camera? In ordinary life--no; for the phonograph has its limitations, like every other machine, and it is not sufficiently sensitive to record a conversation unless it is spoken close at hand. But there is here a chance for the sensational novelist to hang a tale upon.

The 'interviewer' may make use of it to supply him with 'copy,' but this remains to be seen. There are practical difficulties in the way which need not be told over. Perhaps in railway trains, steamers, and other unsteady vehicles, it will be-used for communications. The telephone may yet be adapted to work in conjunction with it, so that a phonogram can be telephoned, or a telephone message recorded in the phonograph. Such a 'telephonograph' is, however, a thing of the future. Wills and other private deeds may of course be executed by phonograph. Moreover, the loud-speaking instrument which Edison is engaged upon will probably be applied to advertising and communicating purposes. The hours of the day, for example, can be called out by a clock, the starting of a train announced, and the merits of a particular commodity descanted on.

All these uses are possible; but it is in a literary sense that the phonograph is more interesting. Books can now be spoken by their authors, or a good elocutionist, and published in phonograms, which will appeal to the ear of the 'reader' instead of to his eye. 'On, four cylinders 8 inches long, with a diameter of 5,' says Edison, 'I can put the whole of NICHOLAS NICKLEBY.' To the invalid, especially, this use would come as a boon; and if the instrument were a loud speaker, a circle of listeners could be entertained. How interesting it would be to have NICHOLAS NICKLEBY read to us in the voice of d.i.c.kens, or TAM O'

SHANTER in that of Burns! If the idea is developed, we may perhaps have circulating libraries which issue phonograms, and there is already some talk of a phonographic newspaper which will prattle politics and scandal at the breakfast-table. Addresses, sermons, and political speeches may be delivered by the phonograph; languages taught, and dialects preserved; while the study of words cannot fail to benefit by its performance.

Musicians will now be able to record their improvisations by a phonograph placed near the instrument they are playing. There need in fact be no more 'lost chords.' Lovers of music, like the inventor himself, will be able to purchase songs and pieces, sung and played by eminent performers, and reproduce them in their own homes. Music-sellers will perhaps let them out, like books, and customers can choose their piece in the shop by having it rehea.r.s.ed to them.

In preserving for us the words of friends who have pa.s.sed away, the sound of voices which are stilled, the phonograph a.s.sumes its most beautiful and sacred character. The Egyptians treasured in their homes the mummies of their dead. We are able to cherish the very accents of ours, and, as it were, defeat the course of time and break the silence of the grave. The voices of ill.u.s.trious persons, heroes and statesmen, orators, actors, and singers, will go down to posterity and visit us in our homes. A new pleasure will be added to life. How pleasant it would be if we could listen to the cheery voice of Gordon, the playing of Liszt, or the singing of Jenny Lind!

Doubtless the rendering of the phonograph will be still further improved as time goes on; but even now it is remarkable; and the inventor must be considered to have redeemed his promises with regard to it.

Notwithstanding his deafness, the development of the instrument has been a labour of love to him; and those who knew his rare inventive skill believed that he would some time achieve success. It is his favourite, his most original, and novel work. For many triumphs of mind over matter Edison has been called the 'Napoleon of Invention,' and the aptness of the t.i.tle is enhanced by his personal resemblance to the great conqueror. But the phonograph is his victory of Austerlitz; and, like the printing-press of Gutenberg, it will a.s.suredly immortalise his name.

'The phonograph,' said Edison of his favourite, 'is my baby, and I expect it to grow up a big fellow and support me in my old age.' Some people are still in doubt whether it will prove more than a curious plaything; but even now it seems to be coming into practical use in America, if not in Europe.

After the publication of the phonograph, Edison, owing, it is stated, to an erroneous description of the instrument by a reporter, received letters from deaf people inquiring whether it would enable them to hear well. This, coupled with the fact that he is deaf himself, turned his thoughts to the invention of the 'megaphone,' a combination of one large speaking and two ear-trumpets, intended for carrying on a conversation beyond the ordinary range of the voice--in short, a mile or two. It is said to render a whisper audible at a distance of 1000 yards; but its very sensitiveness is a drawback, since it gathers up extraneous sounds.

To the same category belongs the 'aerophone,' which may be described as a gigantic tympanum, vibrated by a piston working in a cylinder of compressed air, which is regulated by the vibrations of the sound to be magnified. It was designed to call out fog or other warnings in a loud and penetrating tone, but it has not been successful.

The 'magnetic ore separator' is an application of magnetism to the extraction of iron particles from powdered ores and unmagnetic matter.

The ground material is poured through a funnel or 'hopper,' and falls in a shower between the poles of a powerful electro-magnet, which draws the metal aside, thus removing it from the dress.

Among Edison's toys and minor inventions may be mentioned a 'voice mill,' or wheel driven by the vibrations of the air set up in speaking.

It consists of a tympanum or drum, having a stylus attached as in the phonograph. When the tympanum vibrates under the influence of the voice, the stylus acts as a pawl and turns a ratchet-wheel. An ingenious smith might apply it to the construction of a lock which would operate at the command of 'Open, Sesame!' Another trifle perhaps worthy of note is his ink, which rises on the paper and solidifies, so that a blind person can read the writing by pa.s.sing his fingers over the letters.

Edison's next important work was the adaptation of the electric light for domestic illumination. At the beginning of the century the Cornish philosopher, Humphrey Davy, had discovered that the electric current produced a brilliant arch or 'arc' of light when pa.s.sed between two charcoal points drawn a little apart, and that it heated a fine rod of charcoal or a metal wire to incandescence--that is to say, a glowing condition. A great variety of arc lamps were afterwards introduced; and Mr. Staite, on or about the year 1844-5, invented an incandescent lamp in which the current pa.s.sed through a slender stick of carbon, enclosed in a vacuum bulb of gla.s.s. Faraday discovered that electricity could be generated by the relative motion of a magnet and a coil of wire, and hence the dynamo-electric generator, or 'dynamo,' was ere long invented and improved.

In 1878 the boulevards of Paris were lit by the arc lamps of Jablochkoff during the season of the Exhibition, and the display excited a widespread interest in the new mode of illumination. It was too brilliant for domestic use, however, and, as the lamps were connected one after another in the same circuit like pearls upon a string, the breakage of one would interrupt the current and extinguish them all but for special precautions. In short, the electric light was not yet 'subdivided.'

Edison, in common with others, turned his attention to the subject, and took up the neglected incandescent lamp. He improved it by reducing the rod of carbon to a mere filament of charcoal, having a comparatively high resistance and resembling a wire in its elasticity, without being so liable to fuse under the intense heat of the current. This he moulded into a loop, and mounted inside a pear-shaped bulb of gla.s.s. The bulb was then exhausted of its air to prevent the oxidation of the carbon, and the whole hermetically sealed. When a sufficient current was pa.s.sed through the filament, it glowed with a dazzling l.u.s.tre. It was not too bright or powerful for a room; it produced little heat, and absolutely no fumes. Moreover, it could be connected not in but across the main circuit of the current, and hence, if one should break, the others would continue glowing. Edison, in short, had 'subdivided' the electric light.

In October, 1878, he telegraphed the news to London and Paris, where, owing to his great reputation, it caused an immediate panic in the gas market. As time pa.s.sed, and the new illuminant was backward in appearing, the shares recovered their old value. Edison was severely blamed for causing the disturbance; but, nevertheless, his announcement had been verified in all but the question of cost. The introduction of a practical system of electric lighting employed his resources for several years. Dynamos, types of lamps and conductors, electric meters, safety fuses, and other appliances had to be invented. In 1882 he returned to New York, to superintend the installation of his system in that city.

His researches on the dynamo caused him to devise what he calls an 'harmonic engine.' It consists of a tuning-fork, kept in vibration by two small electro-magnets, excited with three or four battery cells. It is capable of working a small pump, but is little more than a scientific curiosity. With the object of transforming heat direct from the furnace into electricity, he also devised a 'pyro-electric generator,' but it never pa.s.sed beyond the experimental stage.

The same may be said for his pyro-electric motor. His dynamo-electric motors and system of electric railways are, however, a more promising invention. His method of telegraphing to and from a railway train in motion, by induction through the air to a telegraph wire running along the line, is very ingenious, and has been tried with a fair amount of success.

At present he is working at the 'Kinetograph,' a combination of the phonograph and the instantaneous photograph as exhibited in the zoetrope, by which he expects to produce an animated picture or simulacrum of a scene in real life or the drama, with its appropriate words and sounds.

Edison now resides at Llewellyn Park, Orange, a picturesque suburb of New York. His laboratory there is a glorified edition of Menlo Park, and realises the inventor's dream. The main building is of brick, in three stories; but there are several annexes. Each workshop and testing room is devoted to a particular purpose. The machine shops and dynamo rooms are equipped with the best engines and tools, the laboratories with the finest instruments that money can procure. There are drawing, photographic, and photometric chambers, physical, chemical, and metallurgical laboratories. There is a fine lecture-hall, and a splendid library and reading-room. He employs several hundred workmen and a.s.sistants, all chosen for their intelligence and skill. In this retreat Edison is surrounded with everything that his heart desires. In the words of a reporter, the place is equally capable of turning out a 'chronometer or a Cunard steamer.' It is probably the finest laboratory in the world.

In 1889, Edison, accompanied by his second wife, paid a holiday visit to Europe and the Paris Exhibition. He was received everywhere with the greatest enthusiasm, and the King of Italy created him a Grand Officer of the Crown of Italy, with the t.i.tle of Count. But the phonograph speaks more for his genius than the voice of the mult.i.tude, the electric light is a better ill.u.s.tration of his energy than the ribbon of an order, and the finest monument to his pluck, sagacity, and perseverance is the magnificent laboratory which has been built through his own efforts at Llewellyn Park. [One of his characteristic sayings may be quoted here: 'Genius is an exhaustless capacity for work in detail, which, combined with grit and gumption and love of right, ensures to every man success and happiness in this world and the next.']

CHAPTER X. DAVID EDWIN HUGHES.

There are some leading electricians who enjoy a reputation based partly on their own efforts and partly on those of their paid a.s.sistants.

Edison, for example, has a large following, who not only work out his ideas, but suggest, improve, and invent of themselves. The master in such a case is able to avail himself of their abilities and magnify his own genius, so to speak. He is not one mind, but the chief of many minds, and absorbs into himself the glory and the work of a hundred willing subjects.

Professor Hughes is not one of these. His fame is entirely self-earned.

All that he has accomplished, and he has done great things, has been the labour of his own hand and brain. He is an artist in invention; working out his own conceptions in silence and retirement, with the artist's love and self-absorption. This is but saying that he is a true inventor; for a mere manufacturer of inventions, who employs others to a.s.sist him in the work, is not an inventor in the old and truest sense.

Genius, they say, makes its own tools, and the adage is strikingly verified in the case of Professor Hughes, who actually discovered the microphone in his own drawing-room, and constructed it of toy boxes and sealing wax. He required neither lathe, laboratory, nor a.s.sistant to give the world this remarkable and priceless instrument.

Having first become known to fame in America, Professor Hughes is usually claimed by the Americans as a countryman, and through some error, the very date and place of his birth there are often given in American publications; but we have the best authority for the accuracy of the following facts, namely that of the inventor himself.

David Edwin Hughes was born in London in 1831. His parents came from Bala, at the foot of Snowdon, in North Wales, and in 1838, when David was seven years old, his father, taking with him his family, emigrated to the United States, and became a planter in Virginia. The elder Mr.

Hughes and his children seem to have inherited the Welsh musical gift, for they were all accomplished musicians. While a mere child, David could improvise tunes in a remarkable manner, and when he grew up this talent attracted the notice of Herr Hast, an eminent German pianist in America, who procured for him the professorship of music in the College of Bardstown, Kentucky. Mr. Hughes entered upon his academical career at Bardstown in 1850, when he was nineteen years of age. Although very fond of music and endowered by Nature with exceptional powers for its cultivation, Professor Hughes had, in addition, an inborn liking and fitness for physical science and mechanical invention. This duality of taste and genius may seem at first sight strange; but experience shows that there are many men of science and inventors who are also votaries of music and art. The source of this apparent anomaly is to be found in the imagination, which is the fountain-head of all kinds of creation.

Professor Hughes now taught music by day for his livelihood, and studied science at night for his recreation, thus reversing the usual order of things. The college authorities, knowing his proficiency in the subject, also offered him the Chair of Natural Philosophy, which became vacant; and he united the two seemingly incongruous professorships of music and physics in himself. He had long cherished the idea of inventing a new telegraph, and especially one which should print the message in Roman characters as it is received. So it happened that one evening while he was under the excitement of a musical improvisation, a solution of the problem flashed into his ken. His music and his science had met at this nodal point.

All his spare time was thenceforth devoted to the development of his design and the construction of a practical type-printer. As the work grew on his hands, the pale young student, beardless but careworn, became more and more engrossed with it, until his nights were almost entirely given to experiment. He begrudged the time which had to be spent in teaching his cla.s.ses and the fatigue was telling upon his health, so in 1853 he removed to Bowlingreen, in Warren Co., Kentucky, where he acquired more freedom by taking pupils.

The main principle of his type-printer was the printing of each letter by a single current; the Morse instrument, then the princ.i.p.al receiver in America, required, on the other hand, an average of three currents for each signal. In order to carry out this principle it was necessary that the sending and receiving apparatus should keep in strict time with each other, or be synchronous in action; and to effect this was the prime difficulty which Professor Hughes had to overcome in his work. In estimating the Hughes' type-printer as an invention we must not forget the state of science at that early period. He had to devise his own governors for the synchronous mechanism, and here his knowledge of acoustics helped him. Centrifugal governors and pendulums would not do, and he tried vibrators, such as piano-strings and tuning-forks. He at last found what he wanted in two darning needles, borrowed from an old lady in the house where he lived. These steel rods fixed at one end vibrated with equal periods, and could be utilised in such a way that the printing wheel could be corrected into absolute synchronism by each signal current.

In 1854, Professor Hughes went to Louisville to superintend the making of his first instrument; but it was unprotected by a patent in the United States until 1855. In that form straight vibrators were used as governors, and a separate train of wheel-work was employed in correcting: but in later forms the spiral governor was adopted, and the printing and correcting is now done by the same action. In 1855, the invention may be said to have become fit for employment, and no sooner was this the case, than Professor Hughes received a telegram from the editors of the New York a.s.sociated Press, summoning him to that city.

The American Telegraph Company, then a leading one, was in possession of the Morse instrument, and levied rates for transmission of news which the editors found oppressive. They took up the Hughes' instrument in opposition to the Morse, and introduced it on the lines of several companies. After a time, however, the separate companies amalgamated into one large corporation, the Western Union Telegraph Company of to-day. With the Morse, Hughes, and other apparatus in its power, the editors were again left in the lurch.

In 1857, Professor Hughes leaving his instrument in the hands of the Western Union Telegraph Company, came to England to effect its introduction here. He endeavoured to get the old Electric Telegraph Company to adopt it, but after two years of indecision on their part, he went over to France in 1860, where he met with a more encouraging reception. The French Government Telegraph Administration became at once interested in the new receiver, and a commission of eminent electricians, consisting of Du Moncel, Blavier, Froment, Gaugain, and other practical and theoretical specialists, was appointed to decide on its merits. The first trial of the type-printer took place on the Paris to Lyons circuit, and there is a little anecdote connected with it which is worthy of being told. The instrument was started, and for a while worked as well as could be desired; but suddenly it came to a stop, and to the utter discomfiture of the inventor he could neither find out what was wrong nor get the printer to go again. In the midst of his confusion, it seemed like satire to him to hear the commissioners say, as they smiled all round, and bowed themselves gracefully off, 'TRES-BIEN, MONSIEUR HUGHES--TRES-BIEN, JE VOUS FELICITE.' But the matter was explained next morning, when Professor Hughes learned that the transmitting clerk at Lyons had been purposely instructed to earth the line at the time in question, to test whether there was no deception in the trial, a proceeding which would have seemed strange, had not the occurrence of a sham trial some months previous rendered it a prudent course. The result of this trial was that the French Government agreed to give the printer a year of practical work on the French lines, and if found satisfactory, it was to be finally adopted. Daily reports were furnished of its behaviour during that time, and at the expiration of the term it was adopted, and Professor Hughes was const.i.tuted by Napoleon III. a Chevalier of the Legion of Honour.

The patronage of France paved the way of the type-printer into almost all other European countries; and the French agreement as to its use became the model of those made by the other nations. On settling with France in 1862, Professor Hughes went to Italy. Here a commission was likewise appointed, and a period of probation--only six months--was settled, before the instrument was taken over. From Italy, Professor Hughes received the Order of St. Maurice and St. Lazare. In 1863, the United Kingdom Telegraph Co., England, introduced the type-printer in their system. In 1865, Professor Hughes proceeded to Russia, and in that country his invention was adopted after six months' trial on the St.

Petersburg to Moscow circuit. At St. Petersburg he had the honour of being a guest of the Emperor in the summer palace, Czarskoizelo, the Versailles of Russia, where he was requested to explain his invention, and also to give a lecture on electricity to the Czar and his court. He was there created a Commander of the Order of St. Anne.

In 1865, Professor Hughes also went to Berlin, and introduced his apparatus on the Prussian lines. In 1867, he went on a similar mission to Austria, where he received the Order of the Iron Crown; and to Turkey, where the reigning Sultan bestowed on him the Grand Cross of the Medjidie. In this year, too he was awarded at the Paris Exhibition, a grand HORS LIGNE gold medal, one out of ten supreme honours designed to mark the very highest achievements. On the same occasion another of these special medals was bestowed on Cyrus Field and the Anglo-American Telegraph Company. In 1868, he introduced it into Holland; and in 1869, into Bavaria and Wurtemburg, where he obtained the n.o.ble Order of St.

Michael. In 1870, he also installed it in Switzerland and Belgium.

Coming back to England, the Submarine Telegraph Company adopted the type-printer in 1872, when they had only two instruments at work. In 1878 they had twenty of them in constant use, of which number nine were working direct between London and Paris, one between London and Berlin, one between London and Cologne, one between London and Antwerp, and one between London and Brussels. All the continental news for the TIMES and the DAILY TELEGRAPH is received by the Hughes' type-printer, and is set in type by a type-setting machine as it arrives. Further, by the International Telegraph Congress it was settled that for all international telegrams only the Hughes' instrument and the Morse were to be employed. Since the Post Office acquired the cables to the Continent in 1889, a room in St. Martin's-le-Grand has been provided for the printers working to Paris, Berlin, and Rome.

In 1875, Professor Hughes introduced the type-printer into Spain, where he was made a Commander of the Royal and Distinguished Order of Carlos III. In every country to which it was taken, the merits of the instrument were recognised, and Professor Hughes has none but pleasant souvenirs of his visits abroad.

During all these years the inventor was not idle. He was constantly improving his invention; and in addition to that, he had to act as an instructor where-ever he went, and give courses of lectures explaining the principles and practice of his apparatus to the various employees into whose hands it was to be consigned.

The years 1876-8 will be distinguished in the history of our time for a triad of great inventions which, so to speak, were hanging together. We have already seen how the telephone and phonograph have originated; and to these two marvellous contrivances we have now to add a third, the microphone, which is even more marvellous, because, although in form it is the simplest of them all, in its action it is still a mystery. The telephone enables us to speak to distances far beyond the reach of eye or ear, 'to waft a sigh from Indus to the Pole; 'the phonograph enables us to seal the living speech on brazen tablets, and store it up for any length of time; while it is the peculiar function of the microphone to let us hear those minute sounds which are below the range of our una.s.sisted powers of hearing. By these three instruments we have thus received a remarkable extension of the capacity of the human ear, and a growth of dominion over the sounds of Nature. We have now a command over sound such as we have over light. For the telephone is to the ear what the telescope is to the eye, the phonograph is for sound what the photograph is for light, and the microphone finds its a.n.a.logue in the microscope. As the microscope reveals to our wondering sight the rich meshes of creation, so the microphone can interpret to our ears the jarr of molecular vibrations for ever going on around us, perchance the clash of atoms as they shape themselves into crystals, the murmurous ripple of the sap in trees, which Humboldt fancied to make a continuous music in the ears of the tiniest insects, the fall of pollen dust on flowers and gra.s.ses, the stealthy creeping of a spider upon his silken web, and even the piping of a pair of love-sick b.u.t.terflies, or the trumpeting of a bellicose gnat, like the 'horns of elf-land faintly blowing.'

The success of the Hughes type-printer may be said to have covered its author with t.i.tles and scientific honours, and placed him above the necessity of regular employment. He left America, and travelled from place to place. For many years past, however, he has resided privately in London, an eminent example of that modesty and simplicity which is generally said to accompany true genius.

Mechanical invention is influenced to a very high degree by external circ.u.mstances. It may sound sensational, but it is nevertheless true, that we owe the microphone to an attack of bronchitis. During the thick foggy weather of November 1877, Professor Hughes was confined to his home by a severe cold, and in order to divert his thoughts he began to amuse himself with a speaking telephone. Then it occurred to him that there might be some means found of making the wire of the telephone circuit speak of itself without the need of telephones at all, or at least without the need of one telephone, namely, that used in transmitting the sounds. The distinguished physicist Sir William Thomson, had lately discovered the peculiar fact that when a current of electricity is pa.s.sed through a wire, the current augments when the wire is extended, and diminishes when the wire is compressed, because in the former case the resistance of the material of the wire to the pa.s.sage of the current is lessened, and in the latter case it becomes greater.

Now it occurred to Professor Hughes that, if this were so, it might be possible to cause the air-vibrations of sound to so act upon a wire conveying a current as to stretch and contract it in sympathy with themselves, so that the sound-waves would create corresponding electric waves in the current, and these electric waves, pa.s.sed through a telephone connected to the wire, would cause the telephone to give forth the original sounds. He first set about trying the effect of vibrating a wire in which a current flowed, to see if the stretching and compressing thereby produced would affect the current so as to cause sounds in a telephone connected up in circuit with the wire--but without effect.

He could hear no sound whatever in the telephone. Then he stretched the wire till it broke altogether, and as the metal began to rupture he heard a distinct grating in the telephone, followed by a sharp 'click,'

when the wire sundered, which indicated a 'rush' of electricity through the telephone. This pointed out to him that the wire might be sensitive to sound when in a state of fracture. Acting on the hint, he placed the two broken ends of the wire together again, and kept them so by the application of a definite pressure. To his joy he found that he had discovered what he had been in search of. The imperfect contact between the broken ends of the wire proved itself to be a means of transmitting sounds, and in addition it was found to possess a faculty which he had not antic.i.p.ated--it proved to be sensitive to very minute sounds, and was in fact a rude microphone. Continuing his researches, he soon found that he had discovered a principle of wide application, and that it was not necessary to confine his experiments to wires, since any substance which conducted an electric current would answer the purpose. All that was necessary was that the materials employed should be in contact with each other under a slight but definite pressure, and, for the continuance of the effects, that the materials should not oxidise in air so as to foul the contact. For different materials a different degree of pressure gives the best results, and for different sounds to be transmitted a different degree of pressure is required. Any loose, crazy unstable structure, of conducting bodies, inserted in a telephone circuit, will act as a microphone. Such, for example, as a gla.s.s tube filled with lead-shot or black oxide of iron, or 'white bronze' powder under pressure; a metal watch-chain piled in a heap. Surfaces of platinum, gold, or even iron, pressed lightly together give excellent results. Three French nails, two parallel beneath and one laid across them, or better still a log-hut of French nails, make a perfect transmitter of audible sounds, and a good microphone. Because of its cheapness, its conducting power, and its non-oxidisability, carbon is the most select material. A piece of charcoal no bigger than a pin's head is quite sufficient to produce articulate speech. Gas-carbon operates admirably, but the best carbon is that known as willow-charcoal, used by artists in sketching, and when this is impregnated with minute globules of mercury by heating it white-hot and quenching it in liquid mercury, it is in a highly sensitive microphonic condition. The same kind of charcoal permeated by platinum, tin, zinc, or other unoxidisable metal is also very suitable; and it is a significant fact that the most resonant woods, such as pine, poplar, and willow, yield the charcoals best adapted for the microphone. Professor Hughes' experimental apparatus is of an amusingly simple description.

He has no laboratory at home, and all his experiments were made in the drawing-room. His first microphones were formed of bits of carbon and sc.r.a.ps of metal, mounted on slips of match-boxes by means of sealing-wax; and the resonance pipes on which they were placed to reinforce the effect of minute sounds, were nothing more than children's toy money boxes, price one halfpenny, having one of the ends knocked out. With such childish and worthless materials he has conquered Nature in her strongholds, and shown how great discoveries can be made. The microphone is a striking ill.u.s.tration of the truth that in science any phenomenon whatever may be rendered useful. The trouble of one generation of scientists may be turned to the honour and service of the next. Electricians have long had sore reasons for regarding a 'bad contact' as an unmitigated nuisance, the instrument of the evil one, with no conceivable good in it, and no conceivable purpose except to annoy and tempt them into wickedness and an expression of hearty but ignominious emotion. Professor Hughes, however, has with a wizard's power transformed this electrician's bane into a professional glory and a public boon. Verily there is a soul of virtue in things evil.