ris, Velocity of the Galvanic Current in Telegraph Wires. 159 
2. We may suppose the velocity through the earth to be so 
small, that the electrotome after a passage of 742 miles through 
the earth has not reached St. Louis until the whole signal-pause 
and electropea have been transmitted through the wire 1049 ; 
miles. On this theory, the passage of the 742 miles through the 
ground would occupy more than a quarter of a second, and we 
can not tell how much more. 
% The second argument in support of my view is also derived 
from experiment, and although not consisting of so direct a nega- 
tion as the first, partakes of the nature of a reductio ad absurdum 
in a sufficient degree to be perhaps yet more convincing than 
the former. It depends on the comparison of the records of sig- 
nals made at St. Louis and at the nearer stations. 
f we assume that the signals between Washington and St. 
Louis were transmitted through the earth, it is easy by the com- 
parison of the Louisville and St. Louis fillets to determine the 
velocity of propagation in the ground. ‘The St. Louis register 
gives, on the assumption above made, a velocity through the 
earth which would make the time of transmission for 742 miles 
between the termini equal to that required for traversing 528 
‘miles of the wire. is amounts to the same thing as if the 
current between the termini traveled with the same velocity asin 
: the wire, but through a distance of only 528 miles. For con- 
_ Venience of expression, I will speak as though this were the 
ase. The result would be precisely the same. 
We have then, on comparing the different registers, two kinds 
of cases—one in which the distance between the stations is 
shorter through the wire, and the other in which it is shorter 
u 
s + 
Relative Distance. Corresponding Velocity. 
Hyp. L Hyp. Ul Hyp. Lb __ Hyp. iL 
576 | +259 12800 1311 
6 59 10473 1073 
1244 427 1309 "651 
1244 427 17771 10386 
1494 977 11405 1458 * 
1494 977 13484 8817 
2090 1055 14415 7283 
