Torches held in the hand and moved in any particular manner, or alternately displayed and hidden behind a screen, were also used in ancient times as signals.
A night telegraph contrived by the Rev. James Bremner, of the Shetland Islands, and rewarded by the Society of Arts in 1816.
A single light constitutes the whole apparatus and the whole operation consists in its alternate exhibition and concealment. This plan had been found suitable for distances of twenty miles and upwards, and had been successfully put in operation between the light-house on Copeland Island and Port Patrick, on the opposite side of the Irish Channel.
Telegraph Electric
The attempts to render one or other of the phenomena of electricity subservient to the purposes of telegraphy have been numerous. From the earliest date, which we can assign to the existence of an electric telegraph, its essential parts have been the same. There are: 1st, the source of electrical power; 2nd, the conducting material by which this power is enabled to travel to the required locality; and, 3rd, the apparatus by which at the distant end of the line the existence of this power, its amount or the direction of its action is made known to the observer.
In the earlier stages of the invention, the investigations of its promoters were confined to the last of these three essentials, and, so long as the illustration of the idea was confined to the lecture table, this part claimed pre-eminence, but with the proposed application to purposes of general utility there arose the necessity for an equal degree of attention to the two former requisites.
The experiments of Dr. Watson, in England, in 1747, and of Franklin, in 1748, on the banks of the Schuylkill river may have suggested the conveyance of information by means of electricity.
The earliest authenticated instance of any attempt to reduce this to practice appears to have been that of Lesage, of Geneva, in 1774, and of Lomond, in France, in 1787, they employed as an indicator a pair of pith balls suspended from one end of an insulated wire, and at the other end of which was the operator provided with an electric machine, on charging the wire with electricity, the pith balls would exercise mutual repulsion and divergence from one another, but on removing the electrical charge from the wire by the contact of some conductor the balls would collapse.
It is evident that certain numbers of successive divergences might be made to denote particular preconcerted signals.
Subsequently to this the phenomena of the spark, as seen on the passage of electricity through an uninterrupted conductor, was used for the transmission of signals, were the various letters of the alphabet formed in this manner upon a table and connected with each one with a distinct and insulated wire and a particular letter might be rendered visible in a darkened room by passing an electric charge through the appropriate wire, this in fact constituted the telegraph of Reusser or Reiser invented in 1794.