John Munro

“ The microphone is a striking illustration 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. ”

“ 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 unassisted powers of hearing. ”

“ 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 distinguished physicist Sir William Thomson, had lately discovered the peculiar fact that when a current of electricity is passed 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 passage of the current is lessened, and in the latter case it becomes greater. ”

“ The success of the Hughes type-printer may be said to have covered its author with titles 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 circumstances. It may sound sensational, but it is nevertheless true, that we owe the microphone to an attack of bronchitis. ”

“ 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.
The commonest and at the same time one of the most sensitive forms of the instrument is called the 'pencil microphone,' from the pencil or crayon of carbon which forms the principal part of it. This pencil may be of mercurialised charcoal, but the ordinary gas-carbon, which incrusts the interior of the retorts in gas-works, is usually employed. ”

“ We ask in vain for an answer to the question which is upon the lips of every one-What next? The microphone has proved itself highly useful in strengthening the sounds given out by the telephone, and it is probable that we shall soon see those three inventions working unitedly; for the microphone might make the telephone sounds so powerful as to enable them to be printed by phonograph as they are received, and thus a durable record of telephonic messages would be obtained. We can now transmit sound by wire, but it may yet be possible to transmit light, and see by telegraph. ”

“ But although a single pencil microphone will under favourable circumstances transmit these varied sounds, the best effect for each kind of sound is obtained by one specially adjusted. There is one pressure best adapted for minute sounds, another for speech, and a third for louder sounds. A simple spring arrangement for adjusting the pressure of the contacts is therefore an advantage, and it can easily be applied to a microphone formed of a small rod of carbon pivoted at its middle, with one end resting on a block or anvil of carbon underneath. ”

“ The microphone is a discovery as well as an invention, and the true explanation of its action is as yet merely an hypothesis. It is supposed that the vibrations put the carbons in a tremor and cause them to approach more or less nearly, thus closing or opening the breach between them, which is, as it were, the floodgate of the current. ”

“ Again it was proved that the diaphragm or tympanum to receive the impression of the sound and convey it to the carbon button, on which Edison had laid considerable stress, was non-essential; for the microphone, pure and simple, was operated by the direct impact of the sonorous waves, and required no tympanum. Moreover, the microphone, as its name implies, could magnify a feeble sound, and render audible the vibrations which would otherwise escape the ear. The discovery of these remarkable and subtle properties of a delicate contact had indeed confronted Edison ”

“ 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. ”

“ 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. ”

“ We are apparently on the eve of other wonderful inventions, and there are symptoms that before many years a great fundamental discovery will be made, which will elucidate the connection of all the physical forces, and will illumine the very frame-work of Nature. ”

“ The significant proof of it lies in the fact that after the researches of Professor Hughes were published the carbon transmitter was promptly modified, and finally abandoned for practical work as a telephone, in favour of a variety of new transmitters, such as the Blake, now employed in the United Kingdom, in all of which the essential part is a microphone of hard carbon and metal. The button of soot has vanished into the limbo of superseded inventions.
Science appears to show that every physical process is reciprocal, and may be reversed. ”

“ 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. ”

“ 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. ”

“ 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 ”

“ 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 scraps of metal, mounted on slips of match-boxes by means of sealing-wax ”