228 ELECTRIC LIGHTING. 



resulting from the condensation, and that therefore it should 

 exhibit the effects of discharge of static electricity. It is for 

 this reason that, instead of the four candles which may be 

 introduced into each of the four circuits of a Gramme division 

 machine, eight may be placed in each circuit ; but it is neces- 

 sary that the condenser attached to each group of four candles 

 should have an extensive surface, and to attain this each 

 element is made of 32 of the largest sized sheets of tinfoil. 

 Under these conditions the light of each candle appears of 

 undiminished intensity. It remains to be seen whether the 

 generator does absorb a greater amount of motive power ; 

 but no experiments have yet been made on this point. 



According to Jablochkoff, the use of these condensers, 

 which, after Warren de la Rue, he calls exciters, is indis- 

 pensable for obtaining electric lights by derivations of the 

 current. When the experiment is tried without the con- 

 densers, it is found that the lamp which offers the least resist- 

 ance absorbs so much of the current that in a few minutes 

 the others are extinguished. If the derived circuit had a 

 perfectly uniform resistance, satisfactory results might perhaps 

 be obtained in this way ; but there are so many causes for 

 variations of resistance, that it is impossible to reckon on 

 such a uniformity continuing for any length of time. It is 

 only in these condensers that the solution of the problem 

 has been found, at least as regards electric candles. 



The condensers used by Jablochkoff are of a very great 

 size, and they take up a comparatively large space. For a 

 series of four candles they form, as we have seen, a pile of 

 25 elements, of about 75 centimetres high, 80 long, and 50 

 wide, but do not require any particular position, and may be 

 placed in any convenient place. They are made of sheets of 

 tinfoil, separated by thin layers of sealing-wax, or by varnished 

 silk, or by paper covered with paraffin. 



The Jablochkoff candles are now very largely used. In 

 Paris they are set up in four large drapery shops ; at the 

 Besselievre and De la Scala concerts; at the Theatre du 



