Mr. R. H. M. Bosanquet on Practical Electricity. 253 



When the charging is started, the auxiliary battery is 

 removed. An instability of the same sort as that above de- 

 scribed takes place. 



This method is not superior to the last, and is troublesome 

 from requiring the auxiliary battery. 



A very simple mode of charging, where the cells are all 

 similar, is to make them up into two or more parallel circuits, 

 according to the electromotive force available. When there 

 are different kinds of cells this method is troublesome, as the 

 two circuits have to be exactly balanced, and this must be 

 done by trial. Further, the red-lead cells alter during charging 

 as if their resistance diminished, which I take to be caused by 

 the decomposition of the sulphate of lead with evolution of 

 sulphuric acid. It is then necessary to keep watch at the 

 galvanometers in the two parallel circuits and rearrange the 

 circuits when necessar}", which is very troublesome. Latterly, 

 however, I have used this method more. With my machine 

 it would be more suitable for charging about 40 cells. The 

 charging is started with a resistance in the same way as in 

 the first case. 



The next method is an interesting one ; I found it useful 

 when the cells were in good condition, with low resistance 

 and with about 20 cells ; but I have used it also with 30 cells. 

 When the resistance of the cells is high, it is better to use the 

 last method with 30 cells. 



I call the present method the method of balanced charging. 

 It arose in this way : — I began by putting the magnets in a 

 shunt circuit, with a resistance in the magnet circuit ; then 

 accumulators could be charged in the main circuit (armature- 

 terminals), and the current spent in heating the resistance in 

 the magnet circuit went to waste. I therefore tried substi- 

 tuting cells for the resistance in the magnet circuit. I put 

 the two similar quantity galvanometers in the two circuits, 

 and varied the distribution of the cells until the deflections 

 were equal; so that all the cells were getting uniformly 

 charged. I found at once that under certain conditions a 

 balance was established, so that the tension-difference on the 

 two sides of the magnet circuits was small, and that, so long 

 as the balance was maintained, there was no tendency to 

 reversal. 



The following scheme will explain one of these arrange- 

 ments : — 



