(14) S is the retardation due to the particles, and we have I =nTdx(D' - D)/2D.
By dividing a line into two halves the working speed will be dependent upon the KR of the longest half, and as both K and R are directly proportional to the length of the line, the KR product for the half of a circuit is but one quarter that of the whole length of the circuit, and the retardation is correspondingly small.
The actual number of sets of apparatus it was possible to work multiplex depended upon the length of the line, for if the latter were long, retardation effects modified the working conditions.
After a very short interval of time, the length of which depends on the inductive retardation of the cable, the condensers corresponding to C 1 and C3 at the other end begin to be charged from the cable, and since the charge of C3 passes through the receiving instrument I or G the signal is recorded.
The only element of uncertainty was caused by the retardation of the current, which between Potsdam and Teheran (3000 m.) took 0 8.20 to travel; but it is probable that the final value can be accepted as correct to within os 05.