ception), are of iron, and of the size known in trade as aoe 
68 Velocity of the Galvanic Current in Telegraph Wires. 
all other velocities known to us, excepting that of light—as “4 war- 
his 
One of these results, as announced by him, was, that the veloci- 
ty of electricity — the copper wires used, was indeed ap- 
preciable,—-but exceeded that of light through the planetary 
space,” that it ost not be less than 288,000 miles i in a second, 
while light traverses about 196,000 during the same time. 
e telegraphic observations, instituted under the immediate 
direction of Mr. Walker, by the U. S. Coast Survey, for deter- 
mining the differences of longitude between remote stations in 
the United States, led to a very unexpected result,—viz.: that to 
distances between the telegraphic stations. No explanation of 
this phenomenon offered itself, excepting the hypothesis, suggest- 
edt by Walker, and communicated by yourself to the Am. Phil. 
Society in March, 1849, that the time elapsing during the pas- 
sage of the si nals between remote stations was much more con- 
siderable, and the velocity consequently less than had been before 
imagined. . 
ince Walker’s results were first published, the subject has en- 
gaged the attention of numerous astronomers and physicists in 
Europe and America, among whom Mitchel, Fizeau and Stein- 
in which it has forced itself upon the consideration of astrono- 
mers have made it incumbent upon them to enter into a full dis- 
cussion of the subject. 
While in Washington in the month of February last, I accepted 
with pleasure an invitation from Mr. Walker to take Pious in an 
pets north of the Capitol, and the city of St. Louis were con- 
on the 4th February, in one colossal galvanic circuit, and 
but for the damage occasioned by a storm on the sa ay, the 
circuit would have extended even to Dubuque in the territory of 
owa, a distance of some 1500 miles 
The wires of that line of telegraph, and of all I think which 
have been used in the experiments for velocity (with a single ex- 
: me rang, 1834, p. 591, 
L Soc. v. pp, 76, Astr. Nachr., xxix, 54, 
