On the Speed of the Electric Transmission of Signals through Submarine Cables and Land Wires

Abstract

ELECTRO-TELEGRAPHIC operations for the determination of differences of longitude are usually so arranged as to furnish determinations of the speed of transmission of the electric signals. Each of two stations which are telegraphically connected is provided with a clock, and usually with a chronograph also; thus the clock-times at either station may be registered at will on the chronographs at both stations. The difference between the times indicated by the two clocks at any moment is thus readily ascertained, and two values of it will be obtained, one with the current transmitted in one direction, the other with it transmitted in the opposite direction. The difference between these two values indicates the sum of the speeds in both directions; and half the difference is usually called the “retardation on the line” as it indicates the amount by which every signal, on arrival at its destination, is slow on the time of its inception.