252 Mr. R. H. M. Bosanquet on Practical Electricity. 



starting the charging in this form ; but until I had acquired 

 considerable experience and a thorough understanding of the 

 conditions, I frequently failed. 



When this arrangement is once started, and if sufficient 

 power is available to keep it going, it is not only the most 

 economical method of charging with this machine, but is more 

 economical than any other method, excepting the case where 

 the magnets form a shunt circuit of very high resistance 

 indeed. 



The objection to the arrangement in question is that there 

 is a very small margin between the tension of the battery and 

 that of the machine which has to overcome it ; consequently 

 at the slightest check to the steam, and frequently without 

 any apparent cause, the battery-current will overpower the 

 tension of the machine and reverse it. The motion of the 

 machine tends to reinforce the current of the battery in the 

 new condition, and the resistance of the machine is small; 

 so that a tremendous current, probably more than 50 amperes, 

 is poured through the machine, and the electromagnetic 

 attraction resulting is powerful enough to stop the engine. 

 This reversing is indicated by a hiss of the belt on the pulley, 

 followed by the stoppage of the engine. The person in 

 attendance has immediately to break the circuit, or the whole 

 store of electricity would soon be poured uselessly away. 



With the limited power at my disposal I have never been 

 safe from reversals in charging in series in this manner when 

 the number of cells to be charged amounted to twenty or more. 



Another method of starting the charging in series is to 

 throw a current through the magnets from an auxiliary 

 battery or from a series of accumulators already charged, and 

 then introduce those to be charged. The connexions are as 

 follows: — 



Accumulator . 



Auxiliary 



initial 

 current 



In this arrangement one terminal of the magnets must be 

 disconnected from the armature, and the magnets m:.de up 

 into one circuit. 



