94 PHOTO-TELEGRAPHY 



before any important portion of the photograph 

 has been transmitted he can ensure its reception 

 being good. In any optical method of reception, 

 on the other hand, should any error have occurred 

 in the preliminary adjustments, the operator cannot 

 know of his fault until after both the reception has 



FIG. 44. i. Capacity on line. 2. No capacity. 3. Capacity 

 on line, but balancer in shunt. 



Photograph showing the balancing effect of the Telectrograph 

 arrangement. Currents were sent to the receiver by 

 closing a circuit with a Morse key. The chemical marks 

 produced are elongated or "tailed" when capacity is 

 shunted on the line (i). They are short and end abruptly 

 with no capacity (2). The capacity effect is obviated by 

 the balancer (3). 



been completed and the film or sensitive paper has 

 been developed. When we remember that the cost 

 of the telephone line between London and Paris is 

 four shillings for three minutes, or over a farthing 

 a second, the need for rapidity becomes apparent. 

 The machine must be simple, rapid, and, if pos- 

 sible, certain ; the preliminary tests and adjust- 

 ments reduced to the minimum, and the operator 

 himself must be quick and intelligent, and be able 

 to locate a fault rapidly. 



