PRESIDENTIAL ADDRESS, S.T.E. 1874. 225 



careful observer to estimate with practical accuracy 

 the indication that he would have were there no 

 working of the line going on at the time. A 

 magnetic storm of considerable intensity does not 

 stop the working, does indeed scarcely interfere 

 with the working, of a submarine line in many 

 instances when a condenser is used at each end. 

 Thus, observations, even when the line is working, 

 may be made during magnetic storms, and again, 

 during hours when the line is not working if there 

 are any, and even the very busiest lines have 

 occasional hours of rest. Perhaps, then, however, 

 the operators have no time or zeal left, or, rather, 

 I am sure they have always zeal, but I am not 

 sure that there is always time left, and it may be 

 impossible for them to bear the strain longer than 

 their office hours require them. But when there 

 is an operator, or a superintendent, or mechanic, 

 or an extra operator who may have a little time 

 on his hands, then, I say, any single observation 

 or any series of observations that he can make on 

 the electric potentials at one end of an insulated 

 line will give valuable results. 

 VOL. II 



