162 Velocity of the Galvanic Current in Telegraph Wires. 
‘part of the circuit between the clock and Pittsburg. The differ- 
ence between the times of transmission given in the two cases, 18 
so small as to be practically inappreciable, and probably owing to 
the unavoidable errors of reading. 
Eight measurements on the Pittsburg and Cincinnati registers, 
where the battery was not interposed, gave as the time of trans- 
mission from Washington to Pittsburg 0303049. Seventy-four 
measurements on the same registers when the battery was inter- 
6 
Louis register and follows the corresponding one on the Wash- 
ington registers. This was first discovered by Mr. Walker, who 
considerst it to indicate that waves caused by breaking and clos- 
ing the circuit may travel in opposite directions and cross one 
another, without interference. This view is theoretically startling 
to those who have looked on electric phenomena as exhibitions 
of a polar force, and I have examined with great care all the cases 
of this kind which could be found. In none of them can I find 
the distance between the signal-pauses on the two fillets to cor- 
respond, even approximately, to the velocity which the compari 
son of the same fillets indicates. The interval is generally twice 
as great as would be due to the time of transmission. [I have 
been compelled to look in a very different direction for the expla- 
nation of the phenomenon. ‘The St. Louis operator often struck — 
the break-circuit key twice in quick succession ; and in the cases ~ 
under discussion, it would appear that the interval between these 
two consecutive signal-pauses was very nearly equal to the time 
* Pogg. Ann. xlv, 23. ene 
{ Hallat, Comptes Rendus, vi, 52. De la Rive, Arch. de l’Electr,, iii, 288. 
Proceedings Amer. Assoc., Charleston, 1850, p. 124. ine 
