82 



L. Schwendler — Discharge of long Telegraph lines. [No. 1, 



As it was evident that the prolonging effect of the shunt must 

 greatly depend upon its resistance, (supposing the resistance of the 

 discharging relay and also all other circumstances were given), 

 the following investigation was made in order to ascertain its 

 amount. 



Figure 2 represents the simple circuit as obtained from dia- 

 gram 1. 



r 



Fig: 2 



6' 



~ E 



-\r 



Two bobbins of wire, r and b, are connected parallel to the two poles 

 of a battery E, the circuit of which may be closed and opened at will 

 by a stopper, 1 . Only one of the bobbins, r for instance, contains 

 iron, which becomes a magnet as soon as the battery circuit is closed. 

 When the circuit is opened, the magnetism in r ceases, causing 

 an extra current in (r -f- b) which acts in the same direction as the 

 original battery current, and consequently causes the loss of mag- 

 netism in r to go on much slower, than it would without 

 such a shunt b ; and therefore, if the magnetism in r were made 

 use of for closing a contact 2, this contact would be somewhat 

 prolonged by such a shunt. Consequently the question to be solved 

 is, what must be the resistance of this shunt, supposing r, and 

 everything else were given, in order to make the remanent 

 magnetism a maximum, i. e. the prolonging effect of the shunt as 

 regards contact 2 greatest. 



That for a given r a certain b does exist for which the extra 

 current, or its equivalent the remanent magnetism, is greatest, 

 follows simply enough. Suppose for instance the resistance of the 

 shunt b were infinite, which is the same as having no shunt at all, 

 then no extra current would exist, though its cause, •". e. the mag- 



