EARLY TELEGRAPHS.
The ancient Greeks and Romans practised telegraphy with the help of pots filled with straw and twigs saturated in oil, which, being placed in rows, expressed certain letters according to the order in which they were lighted; but the only one of their contrivances that merits a detailed description was that invented by a Grecian general named Æneas, who flourished in the time of Aristotle, intended for communication between the generals of an army. It consisted of two exactly similar earthen vessels, filled with water, each provided with a cock that would discharge an equal quantity of water in a given time, so that the whole or any part of the contents would escape in precisely the same period from both vessels. On the surface of each floated a piece of cork supporting an upright, marked off into divisions, each division having a certain sentence inscribed upon it. One of the vessels was placed at each station; and when either party desired to communicate, he lighted a torch, which he held aloft until the other did the same, as a sign that he was all attention. On the sender of the message lowering or extinguishing his torch, each party immediately opened the cock of his vessel, and so left it until the sender relighted his torch, when it was at once closed. The receiver then read the sentence on the division of the upright that was level with the mouth of the vessel, and which, if everything had been executed with exactness, corresponded with that of the sender, and so conveyed the desired intimation.
We must here pause a moment to point out one great advantage that this contrivance, simple as it undoubtedly was, will be seen to possess over the more scientific ones that follow, and that was, its equal efficacy in any sort of country and in any position, whether on a plain, on the summit of a hill, or in a sequestered valley.
To descend to more modern times. Kessler in his Concealed Arts advised the cutting out of characters in the bottom of casks, which would appear luminous when a light was placed inside. In the Spectator of December 6, 1711, there is an extract from Strada, an Italian historian, who published his Prolusiones Academicæ in 1617. In the passage referred to, the modern system of telegraphy is curiously indicated. It is as follows: 'Strada, in one of his Prolusions, gives an account of a chimerical correspondence between two friends by the help of a certain loadstone, which had such virtue in it, that if it touched two several needles, when one of the needles so touched began to move, the other, though at never so great a distance, moved at the same time and in the same manner. He tells us that the two friends, being each of them possessed of one of these needles, made a kind of dial-plate, inscribing it with the four-and-twenty letters, in the same manner as the hours of the day are marked upon the ordinary dial-plate. They then fixed one of the needles on each of these plates in such a manner that it could move round without impediment so as to touch any of the four-and-twenty letters. Upon their separating from one another into distant countries, they agreed to withdraw themselves punctually into their closets at a certain hour of the day, and to converse with one another by means of this their invention. Accordingly, when they were some hundred miles asunder, each of them shut himself up in his closet at the time appointed, and immediately cast his eye upon his dial-plate. If he had a mind to write anything to his friend, he directed his needle to every letter that formed the words which he had occasion for, making a little pause at the end of every word or sentence, to avoid confusion. The friend, in the meanwhile, saw his own sympathetic needle moving of itself to every letter which that of his correspondent pointed at. By this means they talked together across a whole continent, and conveyed their thoughts to one another in an instant over cities or mountains, seas or deserts.
It was not till near the close of the seventeenth century that a really practical system of visual signalling from hill to hill was introduced by Dr Hooke, whose attention had been turned to the subject at the siege of Vienna by the Turks. He erected on the top of several hills having a sky-line background three high poles or masts, connected at their upper ends by a cross-piece. The space between two of these poles was filled in with timbers to form a screen, behind which the various letters were hung in order on lines, and, by means of pulleys, run out into the clear space between the other two, when they stood out clear against the sky-line. The letters were thus run out and back again in the required order of spelling, and were divided into day and night letters—the former being made of deals, the latter with the addition of links or lights; besides which there were certain conventional characters to represent such sentences as, 'I am ready to communicate,' 'I am ready to receive.' In his description of the device, read before the Royal Society on the 21st of May 1684, Dr Hooke, after claiming for it the power of transmitting messages to a station thirty or forty miles distant, said: 'For the performance of this we must be beholden to a late invention, which we do not find any of the ancients knew; that is, the eye must be assisted with telescopes, that whatever characters are exposed at one station may be made plain and distinguishable at the other.' A cipher code was subsequently added by an ingenious Frenchman named Amontons.
In 1767 we find Mr Richard L. Edgeworth, the father of Maria Edgeworth, employing the sails of a common windmill for communicating intelligence, by an arranged system of signals according to the different positions of the arms. The signals were made to denote numbers, the corresponding parties being each provided with a dictionary in which the words were numbered—the system in vogue for our army-signalling till 1871, when the Morse alphabet was substituted for it.
A great stride was made in 1793 by M. Chappe, a citizen of Paris, when the French Revolution directed all the energies of that nation to the improvement of the art of war; reporting on whose machine to the French Convention in August of the following year, Barère remarked: 'By this invention, remoteness and distance almost disappear, and all the communications of correspondence are effected with the rapidity of the twinkling of an eye.' It consisted of a strong wooden mast some twenty-five feet high, with a cross-beam twelve feet by nine inches jointed on to its top, so as to be movable about its centre like a scale-beam, and could thus be placed horizontally, vertically, or anyhow inclined by means of cords. To each end of this cross-beam was affixed a short vertical indicator about four feet long, which likewise turned on pivots by means of cords, and to the end of each was attached a counterweight, almost invisible at a distance, to balance the weight of it. This machine could be made to assume certain positions which represented or were symbolical of letters of the alphabet. In working, nothing depended on the operator's manual skill, as the movements were regulated mechanically. The time taken up for each movement was twenty seconds, of which the actual motion occupied four; during the other sixteen, the telegraph was kept stationary, to allow of its being distinctly observed and the letter written down by those at the next station. All the parts were painted dark brown, that they might stand out well against the sky; and three persons were required at each station, one to manipulate the machine, another to read the messages through a telescope, and the third to transfer them to paper, or repeat them to No. 1 to send on. The first machine of this kind was erected on the roof of the Paris Louvre, to communicate with the army which was then stationed near Lille, between which places intermediate ones from nine to twelve miles apart were erected, the second being at Montmartre. The different limbs were furnished with argand lamps for night-work.
Shortly after this, our own government set up lines of communication from the Admiralty to Deal, Portsmouth, and other points on the coast, which we find thus reported in the Annual Register for 1796:
March 28th. 'A telegraph was this day erected over the Admiralty, which is to be the point of communication with all the different sea-ports in the kingdom. The nearest telegraph to London has hitherto been in St George's Fields; and to such perfection has this ingenious and useful contrivance been already brought, that one day last week information was conveyed from Dover to London in the space of only seven minutes. The plan proposed to be adopted in respect to telegraphs is yet only carried into effect between London and Dover; but it is intended to extend all over the kingdom. The importance of this speedy communication must be evident to every one; and it has this advantage, that the information conveyed is known only to the person who sends and to him who receives it. The intermediate posts have only to answer and convey the signals.'
The machines used consisted of three masts connected by a top-piece. The spaces between the masts were divided into three horizontally, and in each partition a large wooden octagon was fixed, poised upon a horizontal axis across its centre, so that it could be made to present either its surface or its edge to the observer. The octagons were turned by means of cranks upon the ends of the axles, from which cords descended into a cabin below. By the changes in the position of these six octagonal boards, thirty-six changes were easily exhibited, and the signal to represent any letter or number made: thus, one board being turned into a horizontal position so as to expose its edge, while the other five remained shut or in a vertical position, might stand for A, two of them only in a horizontal position for B, three for C, and so on. It was, however, found that the octagons were less evident to the eye at a distance than the indicators of Chappe's machine, requiring the stations to be closer together; nor could this telegraph be made to change its direction, so that it could only be seen from one particular point, which necessitated having a separate machine at the Admiralty for each line, as well as an additional one at every branch-point. It was, moreover, too bulky and of a form unsuitable for illumination at night.
Here we may notice that in 1801 Mr John Boaz of Glasgow obtained a patent for a telegraph which effected the signal by means of twenty-five lamps arranged in five rows of five each, so as to form a square. Each lamp was provided with a blind, with which its light could be obscured, so that they could be made to exhibit letters and figures by leaving such lamps only visible as were necessary to form the character.
The next improvement again came from France, in 1806, when an entirely new set of telegraphs on the following principle was established along the whole extent of the coast of the French empire. A single upright pole was provided with three arms, each movable about an axis at one end—one near the head, the other two at points lower down, all painted black, with their counterpoises white, so as to be invisible a short way off. Each arm could assume six different positions—one straight out on either side of the pole, two at an angle of forty-five degrees above this line, and two at forty-five degrees below it. The arm near the head could be made to exhibit seven positions, the seventh being the vertical; but as this might have been mistaken for part of the pole, it was not employed. The number of combinations or different signals that could be rendered by this machine, employing only three objects, was consequently three hundred and forty-two against sixty-three by that of our Admiralty just described, and which employed six objects.
It was not long, however, before we copied the advancement of our neighbours across the Channel, and in some respects improved upon it, the main differences being that only two arms were employed—one at the top, the other half-way down, and that the mast was made to revolve on a vertical axis, so that the arms could be rendered visible from any desired quarter. Its mechanism, the invention of Sir Home Popham, enabled the arms to be moved by means of endless screws worked by iron spindles from below, a vast improvement on the old cords, the more so as they worked inside the mast, which was hollow, hexagonal in section, and framed of six boards bound together by iron hoops, and were thus protected from the weather. Inside the cabin he erected two dials, one for each arm, each having an index finger that worked simultaneously with its corresponding arm above, on the same principle as the little semaphore models to be seen nowadays in our railway signal cabins.
We have now described the most prominent of the numerous contrivances which, prior to the application of electricity to that end, were devised and made use of for telegraphic communication, all of which, unlike that subtle power that is not afraid of the dark and can travel in all weathers, possessed a common weakness in their liability to failure through atmospheric causes, fog, mist, and haze. To us who live in this age of electrical marvels, when that particular science more than all others progresses by leaps and bounds, it appears passing strange and almost incredible that so many years were allowed to elapse before the parents of the electric telegraph, the electrical machine and magnetic compass, were joined in wedlock to produce their amazing progeny, which now enables all mankind, however distant, to hold rapid, soft, and easy converse.