John Munro

“ In science, as in morals and politics, there is absolutely no periodicity. One thing we may prophesy of the future for certain—it will be unlike the past. Everything is in a state of evolution and progress. The science of dead matter, which has been the principal subject of my thoughts during my life, is, I may say, strenuous on this point, that the age of the earth is definite. ”

“ It is to the mouse-mill that me must look both for the electricity which is used to electrify the ink and for the motive power which drives the paper. This unique and interesting little motor owes its somewhat epigrammatic title to the resemblance of the drum to one of those sparred wheels turned by white mice, and to the amusing fact of its capacity for performing work having been originally computed in terms of a 'mouse-power.' The mill is turned by a stream of electricity flowing from the battery above described, and is, in fact, an electro-magnetic engine worked by the current. ”

“ It seems to me that when a scientific man says—as it has been said from time to time—that there is no God, he does not express his own ideas clearly. He is, perhaps, struggling with difficulties; but when he says he does not believe in a creative power, I am convinced he does not faithfully express what is in his own mind, He does not fully express his own ideas. ”

“ A core, in fact, is an attenuated Leyden jar; the wire of the core, its insulating jacket, and the soil or water around it stand respectively for the inner tinfoil, the glass, and the outer tinfoil of the jar. When the wire is charged from a battery, the electricity induces an opposite charge in the water as it travels along, and as the two charges attract each other, the exciting charge is restrained. The speed of a signal through the conductor of a submarine cable is thus diminished by a drag of its own making. ”

“ A beam of light is thrown from a lamp upon the mirror, and reflected by it upon a white screen or scale a few feet distant, where it forms a bright spot of light.
When there is no current on the instrument, the spot of light remains stationary at the zero position on the screen; but the instant a current traverses the long wire of the coil, the suspended magnets twist themselves horizontally out of their former position, the mirror is of course inclined with them, and the beam of light is deflected along the screen to one side or the other, according to the nature of the current. ”

“ Sir William Thomson has been all his life a firm believer in the truth of Christianity, and his great scientific attainments add weight to the following words, spoken by him when in the chair at the annual meeting of the Christian Evidence Society, May 23, 1889:—'I have long felt that there was a general impression in the non-scientific world, that the scientific world believes Science has discovered ways of explaining all the facts of Nature without adopting any definite belief in a Creator. ”

“ All its activity depends on the galvanic current. From three separate sources invisible currents are led to its principal parts, and are at once physically changed. That entering the mouse-mill becomes transmuted in part into the mechanical motion of the revolving drum, and part into electricity of a more intense nature—into mimic lightning, in fact, with its accompaniments of heat and sound. That entering the signal magnet expends part of its force in the magnetism of the core. That entering the signal coil, which may be taken as the brain of the instrument, appears to us as intelligence. ”

“ The best operators cannot send over thirty-five words per minute by hand, but a hundred and twenty words or more per minute can be transmitted by an automatic sender, and the recorder has been found on land lines and short cables to write off the message at this incredible speed. When we consider that every word is, on the average, composed of fifteen separate waves, we may better appreciate the rapidity with which the siphon can move. On an ordinary cable of about a thousand miles long, the working speed is about twenty words per minute. ”

“ In the French Atlantic cable no current can be detected by the most delicate galvanoscope at America for the first tenth of a second after it has been put on at Brest; and it takes about half a second for the received current to reach its maximum value. This is owing to the phenomenon of induction, very important in submarine cables, but almost entirely absent in land lines. In submarine cables, as is well known, the copper wire which conveys the current is insulated from the sea-water by an envelope, usually of gutta-percha. ”

“ The alphabet of signals employed is the 'Morse code,' so generally in vogue throughout the world. In the Morse code the letters of the alphabet are represented by combinations of two distinct elementary signals, technically called 'dots' and 'dashes,' from the fact that the Morse recorder actually marks the message in long and short lines, or dots and dashes. In the siphon recorder script dots and dashes are represented by curves of opposite flexure. The condensers are merely used to sharpen the action of the current, and render the signals more concise and distinct on long cables. ”

“ Thomson became a man of public note in connection with the laying of the first Atlantic cable. After Cooke and Wheatstone had introduced their working telegraph in 1839; the idea of a submarine line across the Atlantic Ocean began to dawn on the minds of men as a possible triumph of the future. Morse proclaimed his faith in it as early as the year 1840, and in 1842 he submerged a wire, insulated with tarred hemp and india-rubber, in the water of New York harbour, and telegraphed through it. ”

“ The siphon is, of course, in a mechanical sense, the most delicate part, but, in an electrical sense, the mouse-mill proves the most susceptible. It is essential for the fine marking of the siphon that the ink should neither be too strongly nor too feebly electrified. When the atmosphere is moderately humid, a proper supply of electricity is generated by the mouse-mill, the paper is sufficiently moist, and the ink flows freely. But an excess of moisture in the air diminishes the available supply of exalted electricity. ”

“ The design of the cable was a subject of experiment by Professor Morse and others. It was known that the conductor should be of copper, possessing a high conductivity for the electric current, and that its insulating jacket of gutta-percha should offer a great resistance to the leakage of the current. Moreover, experience had shown that the protecting sheath or armour of the core should be light and flexible as well as strong, in order to resist external violence and allow it to be lifted for repair. ”

“ The siphon and reservoir are together supported by an ebonite bracket, separate from the rest of the instrument, and insulated from it; that is to say, electricity cannot escape from them to the instrument. The ink may, therefore, be electrified to an exalted state, or high potential as it is called, while the body of the instrument, including the paper and metal writing-tablet, are in connection with the earth, and at low potential, or none at all, for the potential of the earth is in general taken as zero. ”

“ Physical science does something for us here. St. Peter speaks of scoffers who said that "all things continue as they were from the beginning of the creation;" but the apostle affirms himself that "all these things shall be dissolved." It seems to me that even physical science absolutely demonstrates the scientific truth of these words. We feel that there is no possibility of things going on for ever as they have done for the last six thousand years. ”

“ The ink, for example, is like a highly-charged thunder-cloud supported over the earth's surface. Now the tendency of a charged body is to move from a place of higher to a place of lower potential, and consequently the ink tends to flow downwards to the writing-tablet. ”

“ One commerce over every land,
One language, and one God.'
The rejoicing reached a climax in September, when a public service was held in Trinity Church, and Mr. Field, the hero of the hour, as head and mainspring of the expedition, received an ovation in the Crystal Palace at New York. The mayor presented him with a golden casket as a souvenir of 'the grandest enterprise of our day and generation.' The band played 'God save the Queen,' and the whole audience rose to their feet. ”

“ On August 16 Queen Victoria sent a telegram of congratulation to President Buchanan through the line, and expressed a hope that it would prove 'an additional link between the nations whose friendship is founded on their common interest and reciprocal esteem.' The President responded that, 'it is a triumph more glorious, because far more useful to mankind, than was ever won by conqueror on the field of battle. ”

“ It is a great improvement on the older instrument, being steadier, less hampered by friction, and the deviation due to the ship's own magnetism can be corrected by movable masses of iron at the binnacle.
Sir William is himself a skilful navigator, and delights to cruise in his fine yacht, the Lalla Rookh, among the Western Islands, or up the Mediterranean, or across the Atlantic to Madeira and America. His interest in all things relating to the sea perhaps arose, or at any rate was fostered, by his experiences on the Agamemnon and the Great Eastern. ”

“ But before it reached the Red Sea the cable had broken down, and the instrument was returned dismantled, to be superseded at length by the siphon recorder, in which the marking point is a fine glass siphon emitting ink, and the moving body a light coil of wire hung between the poles of a magnet.
The principle of the siphon recorder is exactly the inverse of the mirror galvanometer. In the latter we have a small magnet suspended in the centre of a large coil of wire—the wire enclosing the magnet, which is free to rotate round its own axis. ”

“ But it can do something, and that something is vital and fundamental. It is to show that what we see in the world of dead matter and of life around us is not a result of the fortuitous concourse of atoms. ”

“ This earth, certainly a moderate number of millions of years ago, was a red-hot globe; all scientific men of the present day agree that life came upon this earth somehow. If some form or some part of the life at present existing came to this earth, carried on some moss-grown stone perhaps broken away from mountains in other worlds ”

“ The difficulty of producing such a recorder was, as he himself says, due to a difficulty in obtaining marks from a very light body in rapid motion, without impeding that motion. The moving body must be quite free to follow the undulations of the current, and at the same time must record its motions by some indelible mark. As early as 1859, Sir William sent out to the Red Sea cable a piece of apparatus with this intent. The marker consisted of a light platinum wire, constantly emitting sparks from a Rhumkorff coil, so as to perforate a line on a strip of moving paper ”

“ The Board of Trade in 1859 had appointed a committee of experts, including Professor Wheatstone, to investigate the whole subject, and the results were published in a Blue-book. Profiting by these aids, an improved type of cable was designed. The core consisted of a strand of seven very pure copper wires weighing 300 lbs. a knot, coated with Chatterton's compound, which is impervious to water, then covered with four layers of gutta-percha alternating with four thin layers of the compound cementing the whole, and bringing the weight of the insulator to 400 lbs. ”

“ Strong head winds kept the Agamemnon back, and two American ships which got into her course had to be warned off by firing guns. The signals from the Niagara became very weak, but on Professor Thomson asking the electricians on board of her to increase their battery power, they improved at once. At length, on Thursday, August, 5, the Agamemnon, with her consort, the Valorous, arrived at Valentia Island, and the shore end was landed into the cable-house at Knightstown by 3 p.m., and a royal salute announced the completion of the work. ”

“ This measurer of the current was infinitely more sensitive than any which preceded it, and enables the electrician to detect the slightest flaw in the core of a cable during its manufacture and submersion. Moreover, it proved the best apparatus for receiving the messages through a long cable. The Morse and other instruments, however suitable for land lines and short cables, were all but useless on the Atlantic line, owing to the retardation of the signals; but the mirror instrument sprang out of Thomson's study of this phenomenon, and was designed to match it. ”

“ The mirror instrument has this drawback, however—it does not 'record' the message. There is a great practical advantage in a receiving instrument which records its messages; errors are avoided and time saved. It was to supply such a desideratum for cable work that Sir William Thomson invented the siphon recorder, his second important contribution to the province of practical telegraphy. He aimed at giving a graphic representation of the varying strength of the current, just as the mirror galvanometer gives a visual one. ”

“ It seemed as though a great and valued friend lay at the point of death.
The submarine hill, with its dangerous slope, was passed in safety, and the 'telegraph plateau,' nearly two miles deep, was reached, when suddenly the signals from Ireland, which told that the conductor was intact, stopped altogether. Professor Morse and De Sauty, the electricians, failed to restore the communication, and the engineers were preparing to cut the cable, when quite as suddenly the signals returned, and every face grew bright. ”