Discoveries and Inventions of the Nineteenth Century

many coffee-houses would assist him, if necessary, in proving an alibi; but, whatever may have been his motives or his thoughts, he had scarcely entered the lodging when the policeman—who, like a wolf, had followed 551him every step of the way—opening his door, very calmly said to him—the words, no doubt, were infinitely more appalling to him even than the scream that had been haunting him—‘Haven’t you just come from Slough?’ The monosyllable, ‘No,’ confusedly uttered in reply, substantiated his guilt. The policeman made him his prisoner; he was thrown into jail, tried, found guilty of wilful murder, and hanged. A few months afterwards, we happened to be travelling by rail from Paddington to Slough, in a carriage filled with people all strangers to one another. Like English travellers, they were mute. For nearly fifteen miles no one had uttered a single word, until a short-bodied, short-necked, short-nosed, exceedingly respectable-looking man in the corner, fixing his eyes on the apparently fleeting posts and rails of the electric telegraph, significantly nodded to us as he muttered aloud, ‘Them’s the cords that hung John Tawell!’” So far we have followed Wheatstone and Cooke, because these gentlemen were the first who in any country made the electric telegraph a success on the great scale. Elsewhere than in England, laboratories and observatories had been connected by experimental lines, and models had been exhibited to Emperors, but these two Englishmen were the first to construct a telegraph for practical use. It must not, however, be supposed that they are entitled to be considered the exclusive inventors of the electric telegraph, for we have already named other distinguished investigators who contributed their share to this remarkable invention. And some years before Wheatstone and Cooke had patented their first needle telegraph, the first ideas of a system which has largely superseded the needles for ordinary telegraphic purposes, had presented themselves to a mind capable of developing them into the most efficient form of telegraphic apparatus which we possess. In October, 1832, among the passengers on board the steamship Sully, bound from France to the United States, was a talented American artist who had gained some reputation in his profession. A casual conversation with his fellow-passengers on electricity, and the plan by which Franklin drew it from the clouds along a slender wire, suggested to the artist the possibility of thus communicating intelligence by signals at a distance. He named his notion to a fellow-passenger, Dr. Jackson, an American professor, who had devoted some attention to electrical science, and this gentleman suggested several possible (and impossible) methods in which the thing might, as he thought, be accomplished. None of these suggestions, however, indicated the direction in which the idea afterwards took practical form in Morse’s hands. Jackson had among his baggage in the hold, and therefore inaccessible on the voyage, a galvanic battery and an electro-magnet, and these he described to the painter by the aid of rough sketches. When, some years afterwards, Morse had realized his ideas of electric communication, and success was bringing him the favour of fortune, Jackson advanced a claim to a share in the invention, and a famous lawsuit, Jackson v. Morse, was ended by a verdict in favour of Morse, which public and scientific opinion has unanimously endorsed. In reference to this matter, Mr. R. Sabine, the author of an excellent little treatise on “The History and Progress of the Electric Telegraph,” has thus placed the subject in its true light: “Two men came together. A seed-word, sown, perhaps, by some purposeless remark, took root in fertile soil. The one, profiting by that which he had seen and read of, made suggestions, and gave explanations of phenomena and constructions only imperfectly understood by himself, and entirely new to the other. The theme interested both, and became a subject 552of daily conversation. When they parted, the one forgot or was indifferent to the matter, whilst the other, more in earnest, followed it up with diligence, toiling and scheming ways and means to realize what had only been a dream common to both. His labours brought him to the adoption of a method not discussed between them, and Morse became the acknowledged inventor of a great system. Fame and fortune smiling upon the inventor, it was natural enough that Jackson, awakening from his unfortunate indolence, should remember his share in their earlier interchange of ideas, that had, perhaps, first directed Morse’s attention to the subject of telegraphy. And, although we are compelled to pronounce dishonest those attempts which Jackson made to claim the later and proper invention of Morse—that of the electro-magnetic recorder—and strong as is our confidence in the spotless integrity of our friend, we cannot entirely ignore Jackson—little as he has done—nor deny him an inferior place amongst those men whose names are associated with the history and progress of the electric telegraph in America.” From the time of this chance conversation with Dr. Jackson, Morse devoted his mind entirely to the subject of telegraphic communication, and although then more than forty years of age, he abandoned the profession in which he had already gained some distinction, and with the energy and elastic power of adaptability which characterize the American mind, he gave himself up to this new pursuit to such good purpose, that a few years afterwards saw his telegraph system completely established in the United States, where the lines now exceed 20,000 miles in length. At the instigation of the late Emperor of the French, the Governments of France, Belgium, Holland, Austria, Sweden, Russia, Turkey, and the Papal States, combined to award to Professor Morse, in recognition of his services to practical science, the sum of £16,000. It was in 1836 that Morse had first brought his notions into a practical form, but his apparatus has since received many improvements at his own hands, or by the useful modifications of it which have been proposed by others. The transmitting key invented by Morse has proved a valuable piece of apparatus, and its simplicity has contributed much to the success of his invention. Telegraphs on this system were erected in America in 1837, and the Morse apparatus is now more extensively used than any other in every country. In 1840 Professor Wheatstone had succeeded in most ingeniously applying electro-magnetism in such a manner as actually to realize Strada’s sympathetic needles, by having the letters of the alphabet arranged round the circumference of a circle, and pointed at by a revolving hand. Such a dial is provided at each end of the line, and the sender of the message has only to make the index of his own dial pause for an instant at any letter; the hand of his correspondent’s dial will also pause at the same letter. These dial telegraphs are particularly convenient for many purposes, as they do not require a trained telegraphist to read or send the messages. Wheatstone’s plan has been greatly simplified by Breguet, of Paris, and others, and it is much used in mercantile and public establishments. From the foregoing discursive historical indication of the progress of the electric telegraph we shall now proceed to describe the systems most commonly employed in practical telegraphy, with a brief reference to some other interesting forms; and in following these descriptions, the reader will find the advantage of an acquaintance with the electrical facts discussed in the last article, with which facts we shall presume he has become to a certain extent familiar. 553In every telegraphic system there are three distinct portions of the apparatus, which may be separately considered, as they may be variously combined. We have— 1º. The apparatus for producing the electricity, such as batteries, magneto-electric machines, &c. 2º. The conductors, or wires, which convey the electricity. 3º. The apparatus for sending and for receiving the messages. Of the first we shall have little to add to what has been said in the last article; and before entering upon the description of the second, it will be better to discuss the third division. TELEGRAPHIC INSTRUMENTS. Telegraphs may conveniently be classed according to the mode in which the actions of the sender produce their effect at the point where the message is received. A first class may include those in which the current is made to deflect magnetized needles; a second may comprise those in which the current, by magnetizing soft iron, causes an index to travel along a dial and point to the letter intended; a third may embrace those in which the same action on soft iron is made to print the despatches, either in ordinary type or in conventional signs; while in a fourth class we may put the instruments which give their indications by sounds only. It is obvious that in some of these systems signs only are used, and a special training and acquaintance with the symbols is necessary, while in the rest the ordinary alphabetic letters are shown or recorded. In the former case the apparatus is simpler, and therefore for the general business of public telegraphy it is almost exclusively employed; while for private purposes, where it is often required that the messages should be dispatched and received by persons not acquainted with the symbolic language, the dial telegraph, or that which prints the message in ordinary characters, will continue to be employed, in spite of the greater complexity and greater liability to derangement of the apparatus. In the needle telegraphs the essential part of the apparatus is a multiplier (page 493), having its needle mounted vertically on a horizontal axis, to which is also attached an indicator, visible on the face of the instrument, and formed either of a light strip of wood, or of another magnetized needle, having its poles placed in the reverse position to those of the needle within the coil. When the current is sent through the latter, the index is deflected to the right or left, according to the direction in which the current passes. Fig. 282 represents the exterior of one of Wheatstone and Cooke’s double-needle instruments, now almost entirely superseded, where needles are used at all, by the single-needle instrument. The face of the instrument is marked with letters and signs, which were supposed to aid the memory of the telegraphist, and the movements of the needles were chosen rather with that view than any other. We need not here give the code of signals, as the double instrument is now obsolete, and the code for the single-needle instrument, which was devised by Wheatstone and Cooke, has been in most cases superseded by one corresponding with the Morse code, a deflection to the right representing a dot, and a deflection to the left a dash. 554 Fig. 282.—The Double-Needle Instrument. The smaller case surmounting the instrument, Fig. 282, contains a bell or alarum, which serves to call the attention of the clerk at the receiving station. The first electric bell-alarum was invented by Wheatstone and Cooke. It was simply a clock alarum, put in motion by a wound-up spring. The spring was released at the proper moment by a detent, which was removed by the attraction of a soft iron armature to the core of a small electro-magnet, formed by the line wire itself; but when the current, on account of the length of the line, was too weak to produce a sufficiently strong electro-magnet, Wheatstone caused it to close the circuit of a local battery. The electric alarum has been modified in a thousand ways, and as electric alarums or bells are now coming into common use in hotels, and even private houses, we give in Fig. 283 a representation of one of the simplest forms, in which the bell is rung continuously by the electric current so long as the circuit is closed. The action is very simple: a soft iron armature, A, is attached to the steel spring, B, and prolonged into a hammer, C, which strikes the bell, D, every time the armature is attracted to the electro-magnet. The armature and the spring, E, form part