Wireless Transmission of Photographs / Second Edition, Revised and Enlarged 1919

by Marcus J. Martin

M, terminals for connecting to electric clock; L, white lamp; L¹, blue lamp; L², red lamp.

The lamps are coloured, the lamp L being white, and the lamps L¹ and L² blue and red respectively, and care must be taken in connecting up that when the needle K makes contact with the stud P the white lamp L is in circuit. When the machines are working, the operator, by means of the brake (already described), reduces the speed of the driving motor until the needle K travels in unison with the disc J, making permanent contact with P on the contact

block Q, which is evidenced by the lamp L remaining alight. If, however, the needle travels faster than the disc J, contact with P is broken and fresh contact is made with P², the lamp L is extinguished and the red lamp L² lights up, and remains alight until the operator reduces the speed. Similarly, too, if the needle travels slower than J, contact is made with P¹, and the circuit of the blue lamp L¹ is completed. When the speed is either above or below the normal, the needle K engages with one or the other of the pins D, and as the tension of the driving belt is only such as is required to drive the needle, the belt slips on the pulleys until the normal speed is regained.

Method of Working

The clockwork motor M, Fig. 51, should be capable of running for several hours with one winding, and powerful enough to take up the work of driving the machine without any appreciable effort. The main spindle of the motor is so arranged that it makes one revolution in two minutes, and the reduction in speed between the motor shaft and the shaft to which the coupling A is attached is 30:1. The metal line print having been wrapped round the drum of the machine, the stylus is put into position, at the edge of the lap, and with the needle resting about half-way on

the margin of the bare foil left at the commencing edge of the print. Now, when the two stations are in perfect readiness for work, the motors are started and the speed adjusted; the speed of the machine being just under one revolution in four seconds.

M, clockwork motor; S, isochroniser; E, friction break; T, brushes; F, electric clutch; X, gearing; D, D¹, switches; A, flexible coupling; K, polarised relay; L, circuit breaker; B₁, B₂, B₃, batteries; P, electric clock; W, terminals for connection to telephone relay; H, terminals for connection to terminals J, on transmitting machine.