412 



Prof. Ayrton and Mr. Medley on 



The rise in candle-power with time, which occurred during 

 the early part of the life of all the Edison- Swan lamps which 

 we tested, may be noticed also in the collection of curves 

 published by Mr. Feldman in the ' Electrician/ Nov. 29th, 

 1892 (fig. 11). But there are certain very important differ- 

 ences between the results recorded by these curves and those 



Fig. 11. 



400 500 600 



Time in Hours. 



700 800 



900 



1100 1200 



which we have obtained. These differences are shortly as 



follows: — 



(1) The greatest rise of light emitted by the lamps as re- 

 corded in Mr. Eeldman's curves was 14 per cent. In 

 our experiments this maximum rise was 45 per cent. 

 In spite of the first rise in the candle-pow T er as shown 

 in Mr. Feldman's curves (fig. 11), the candle-power at 

 the end of the life of the lamps was in all cases much 

 less than it was when the lamps were new. Whereas 



(2) 



