Velocity of the Galvanic Current in Telegraph Wires. 75 
ring. When it is necessary to conceive some actual mode of 
transmission of signals, I am accustomed to represent it to myself 
in this way. The experiments of Wheatstone show thatthe 
tached to the armature-lever makes its mark upon the paper, All 
these processes require time, and the absolute interval, elapsed be- 
tween the electropea signal and its record on the paper fillet, is 
thus very considerably larger than that due to the time of trans- 
F mission of the signal along the wire. ‘The difference consists— 
Ist, of the induction-time, or time which elapses after the cur- 
as been induced in the iron to overcome the tension of the spi- 
ral spring, and move the armature. | 
2d, of the pass-time, or time required by the armature for trav- 
ersing the pass, and closing the local circuit. 
_8d, of the time of transmission of the electropoea 1m the local 
circuit. 
battery is constant, the last three quantities remain the same for 
i , and exert no influ- 
“a. ive one is connected with the ome gb ot coating 0 . 
es an imitation of a broken circuit connec ith a battery. r 
_ between the exterior of the last jar in the series and the interior of the first, either 
throu igh a discharging rod or through the ground, corresponds to Fs beri gid 
e-cireuit, The difference between the charge of the first 
‘the resistance to conduction. 
rent is established in the helix, before sufficient magnetic power — 
i, $$ 516, 1630. + Walker, Astr. Journ., i, p. 52. 
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