Velocity of the Electric Current. 



169 



An examination of this table reveals no law, except that 

 apparently the shorter the circuit and the more delicate 

 the instrument, the greater is the velocity. 



Circuits were secured on the nights of April 8th, May 

 20th and May 27th. But owing to want of uniformity in 

 the adjustments and manipulations of the instruments, 

 only those results, obtained on the 27th, can be employed 

 for determining the law of propagation. 



Relays. 



Three different relays were used in these experiments 

 the approximate resistances of which, are as follows : 



No. 1, . 30 miles of No. 9 wire, Tillotson, maker. 

 2, 55 " " " " " ' Day, " 



35 " " " " " Williams, " 





Nos. 1 and 3 were placed at the ends of the circuit. No. 

 2 could be switched in either end at pleasure, or cut out 

 entirely. 



Switch Board. 



A special switch board, was constructed which was capable 

 of the following manipulations : 



1. Relay No. 2 could be thrown in either end of the circuit. 



2. Relay No. 2 could be thrown out entirely. 



[ Trans. vi.~] 22 



