Varley, who proposed to make use of it in a telegraphic receiving instrument.4 In Dolbear's instrument one plate of a condenser was a flexible diaphragm, connected with the telephone line in such a way that the varying electric potential produced by the action of the transmitting telephone caused an increased or diminished charge in the condenser.
Oliver Heaviside showed mathematically that uniformly-distributed inductance in a telephone line would diminish both attenuation and distortion, and that if the inductance were great enough and the insulation resistance not too high the circuit would be distortionless, while currents of all frequencies would be equally attenuated.
There is a complete postal and telegraphic service and a telephone line connects all government stations.
The telephone is largely used in the big towns, and there is a trunk telephone line connecting Alexandria and Cairo.
The local modem would then arbitrate with the distant modem for use of the telephone line.