on the Wires of the Electric Telegraph. 29 
wire, and these would constantly vary in intensity with the dif- 
ferent positions of the cloud. Although currents produced in 
this way may be too feeble to set in motion the marking appa- 
ratus, yet they may have sufficient power to influence the action 
of the current of the battery so as to interfere with the perfect 
operation of the machine. 
down into the well ; at every flash of lightning a series of cur- 
rents in alternate directions was produced in the wire. 39 
I was also led, from these results, to infer that induced cur- 
80 
rents must traverse the line of a railroad, and this I found to be 
