Early Attempts at Electrical Communication

It is of interest to consider the extent of electrical knowledge at this time. Gilbert had found by 1600 that a large number of substances when rubbed attracted light objects. In 1629 Cabeo described his theory of electric repulsion in electrified bodies. The first electrical machine, consisting of a sulfur ball rubbed with the hand, was developed by von Guericke in 1650. This fundamental invention was further perfected until it was possible to generate very high voltages by frictional methods. The battery and the electrical generator employing electromagnetic induction, however, were not yet available.

The early methods of transmitting intelligence were by telegraph systems, the word "telegraph" being derived from the Greek words tele meaning distant, and graphein meaning to write. Morrison in 1753 is credited with having suggested the first telegraph system. A separate circuit was to be used for each character to be signaled. A frictional generator producing a high voltage was to be connected at the sending end, and small pieces of paper would be attracted by suitable electrodes at the distant station. Some years later this method was put into operation, but like all the devices based on electrostatic attraction it was of little value.

The first attempt at electrical telegraphy was made by Lessage in 1774, using a system similar to that suggested by Morrison. Letters were signaled by the divergence of pithballs. A revolutionary idea was introduced by Lomond in 1787; he used a similar system but employed one wire and a code of signals. Other methods employing spark discharges at the receiving end to identify the signals were introduced by Reusser (1794) and Cavallo (1795).

All these methods are chiefly of historic interest; with the possible exception of the idea of a code as introduced by Lomond, these early systems contributed little to the present telegraph.