76 Velocity of the Galvanic Current in Telegraph Wires. 
quantities to deal with,—the time of transmission and the induc- 
tion and pass-times of the main circuit. ; 
The record of the electrotome signal is not so much exposed 
to accidental disturbance. The moment that the current ceases 
in the helix, the enclosed iron begins to lose its magnetic condi- 
tion, and as soon as it has parted with its magnetism sufficiently 
to allow the tension of the spiral spring to draw off the armature, 
the local circuit is broken. 'The outward pass-time has no influ- 
ence upon the register. ‘The only quantity to be considered is 
the time elapsing between the cessation of the current in the he- 
lix and the loss of magnetism in the iron. This juterval is the 
converse of the induction-time, and might therefore be denomi- 
nated the eduction-time. 
The same that has been remarked of the corrections in the 
ease of an electropm@a holds true with regard to the propagation 
of an electrotome through the local circuit, and the eduction-time 
in its-electro-magnet. The local-circuit adjustments being well 
made and continuing unchanged, and the intensity of the battery 
remaining constant,—the error from these sources is the same for 
all electrotomes and electropeeas, 
h 
magnet is limited by the condition that the tension of the spiral 
Spring must be strong enough to wi 
