THE ELECTRIC LIGHT 457 



These determinations were made with extreme care and 

 accuracy by Mr. Douglass, the engineer- in- chief, and Mr. 

 Ayres, the assistant engineer of the Trinity House. It is 

 practically impossible to compare photometrically and di- 

 rectly the flame of the candle with these sun-like lights. 

 A light of intermediate intensity — that of the six-wick 

 Trinity oil lamp — was therefore in the first instance com- 

 pared with the electric light. The candle power of the oil 

 lamp being afterward determined, the intensity of the elec- 

 tric light became known. The numbers given in the table 

 prove the superiority of the Alliance machine over that 

 of Holmes. They prove the great superiority both of the 

 Gramme machine and of the small Siemens machine over 

 the Alliance. The large Siemens machine is shown to 

 yield a light far exceeding all the others, while the coup- 

 ling of two Grammes, or of two Siemens together, here 

 effected for the first time, was followed by a very great 

 augmentation of the light, rising in the one case from 

 6,663 candles to 11,896, and in the other case from Q^^Q^ 

 candles to 14,134. "Where the arc is single and the ex- 

 ternal resistance small, great advantages attach to the 

 Siemens light 



After this contest, which was conducted throughout in 

 the most amicable manner, Siemens machines of type No. 

 2 were chosen for the Lizard. * 



"We have machines capable of sustaining a single light, 

 and also machines capable of sustaining several lights. 

 The Gramme machine, for example, which ignites the 



* As the result of a recent trial by Mr. Schwendler, they have been, also 

 chosen for India. 



SCIENCE^VI— 20 



