Proceedings, <Scc, for 1885. 177 



The usual method of using the secondary battery is to arrange 

 for a constant supply of current less than is required for the total 

 power of the lamps to be supplied, but more than the minimum 

 power used. When a small number of lamps are lit, the balance of 

 current from the dynamo goes to charge the battery which will be 

 used conjointly with the dynamo when the full power is required 

 for the lamps. 



The only serious objection to the secondary battery is an obvious 

 one — its leakiness — and this cannot well be provided against. 



Such are the main points to be considered and difficulties to be 

 overcome in designing a system of electric lighting. And from 

 what has been said it can readily be understood there is very wide 

 room for improvement, even in the broadest outlines. But, even 

 after having chosen the particular system to be used, there is still 

 an almost infinite number of details to be considered, all of them 

 important, and no one of which can be overlooked. We have only 

 to mention a few of these to bring this conclusion very forcibly 

 home to your minds — the dynamo, with its general outline, style 

 of winding, speed, class of armature, commutator, terminals and 

 fittings, lubricators, ventilators, &c. But after all these have been 

 satisfactorily arranged, we must face all the difficulties of the mains y 

 switches and branches, the lamps and holders, the safety-fuse, the 

 carriage and insulation of the mains, the main and branch junction 

 boxes, the magnetic cut-outs, the regulators of potential and 

 current, and the testing arrangements. 



It is the blending of all these into one harmonious whole, every 

 contingency being foreseen and having its pre-arranged remedy, 

 and where necessary its appropriate piece of mechanism, that 

 constitutes an electric system. 



N 



