NATURAL PHILOSOPHY. 1G1 



must depend upon the character of the intervening conductor. 

 The question as to the route by which signals are transmitted 

 when part of the circuit is formed by the earth, is thus disposed 

 of; and the position maintained in the memoir above cited is 

 entirely corroborated, although it loses its theoretical significance. 



The duration of one signal current was intended to be uni- 

 formly one-quarter of a second, but depended upon the skill and 

 care of the observer, no automatic signal-giver having been em- 

 ployed. Every electrician knows how greatly the strength of the 

 current is augmented by an increase of its duration from 0.2 s to 

 0.3 s , yet the duration of the signals varied frequently through a 

 larger range than this. Still the actual length of each signal as 

 recorded upon the chronograph register, and its average did not 

 vary much from the prescribed duration of 0.25 s . 



It appears manifest that not an electrical charge or discharge, 

 but simply anelectrical disturbance, is requisite for transmitting a 

 signal ; that an inductive impulse, sufficient to deflect the galva- 

 nometers employed, was transmitted through 1 cable, having at 

 each end a condenser with 10 cells, in somewhat less than the 

 third of a second, 5 seconds after the transmission of an impulse 

 of the opposite sort ; that with a circuit formed by the 2 cables, a 

 smaller electromotive force sufficed to transmit the signals with 

 yet greater rapidity ; that the signals travelled more rapidly 

 through a cable which had not recovered its electrical equilibrium 

 alter a current of the opposite character; and that the speed of 

 the signals is modified by the earth connections more rapidly than 

 by changes in the battery power. And the very marked differ- 

 ences found in the rates of transmission, between signals given by 

 completing an interrupted circuit and those given by interrupting 

 a closed circuit, may perhaps lead to investigations which will 

 afford an explanation. 





