362 
Recent Advances in Telegraphy. 
(July, 
gave the artificial line an equivalent inclusive capacity, and 
produced a counterfeit “ kick ” in the opposite direction, by 
the addition of the condenser. Steam’s system has achieved 
a wide application in the United States. 
Stearns’s Key. 
Cerulervfer 
Another successful duplex method on land-lines is that of 
Mr. G. K. Winter, of Madras. It is called the method of 
“ opposed batteries,” and consists essentially of the “differ- 
ential method but whereas in the latter the battery circuit 
is only completed in the aCt of sending a signal, in the 
former the circuit is closed, so that the batteries at each 
station oppose each other through the line. 
Stimulated by their successes on land-lines, both Winter 
and Stearns, as well as others, in 1873 began to turn their 
attention to the far more difficult task of duplexing sub- 
marine cables. The marked induCtive effeCt of the earth 
on a submarine cable — which resembles an attenuated 
Leyden jar— greatly complicated the requirements of the 
balance. The eleCtric signal travels through a cable in the 
form of a wave, and is sensibly retarded by the earth’s in- 
duction. 
How to produce an artificial line which should be 
electrically equivalent to the aCtual cable in all its effects 
on the current. This was one way of solving the problem. 
Another lay in finding some contrivance or device (mechan- 
ical or otherwise) which should counteract the effect of the 
prolonged inductive charge of the cable on the receiving 
instrument, so as still to produce a balance. 
As early as 1862 Mr. Varley had invented an artificial 
cable, for use as a circuit on which to test the working of 
