Velocity of the Galvanic Current in Telegraph Wires. 157 
Pitisburg Signals. 
Register. No. obs. Interval. | Prob. error. | Velocity. | Min. limit. | Max. limnit. | 
: 0:0295 0:00154 | 19525 18557 20601 
‘ 36 00317 000233 | 18170 16926 1961 
L. | 37 0:0347 | 00258 | 16591 15451 | 17922 
St. L. 10 0°0405 000249 | 12659 12003 1339 
Classifying these according to the stations whose distances are 
+ measured by the recorded values. . 
Stations, | Mean Interval.) No. obs. 1 Ded’d Velocity. | 
Pittsburg. .............. 0°03567 152 16147 miles per second. 
a 008289 196 15008 
co nie ee 0°12291 147 12156 
eee | 014510 61 14404 
The combination of all these, according to the method of least 
Squares, gives, as the result of the experiments of Feb. 4, a ve- 
locity of 14900 miles, with a probable error of the mean = +10 
These last tables seem to answer conclusively the first of the 
questions just propounded,—and at the same time to suggest the 
seco e are justified in assuming that the signals, given by 
making and breaking the galvanic circuit of the telegraph, reach 
the several stations successively in their order of distance, and 
traveling with a finite and measurable velocity. But do they 
and another back. But in all the lines in use in this country, 
the earth forms one half of the circuit. Are we to consider, 
when the two distant extremities of a line of wire communicate 
With the earth at a distance of many hundred miles from one 
another, that there is a special line of tension through the earth 
rom one extremity to the other? and that a signal is communi- 
cated from terminus to terminus through the ground, in the same 
manner as it is through the wire? or may we consider the earth 
_ 48 a huge receptacle, to speak metaphorically, capable of receiv- 
mig or imparting any amount of electricity at any time? ‘The 
rmer opinion is held by my friend Mr. Walker. = 
But does it not seem improbable that the slight activity of a 
Vanic battery, traversing a circuit of 1000 miles of wire, should 
ufficient to establish a special line of electric tension extend- 
rough the earth in a cord or parallel with the surface for 
For my own part, when I remember not only the 
