32 Electric Light 



and either propels a car, or turns other machinery. When 

 electricity is employed for the propulsion of tramcars, the 

 current may be conveyed along an insulated rail or cable, and 

 collected by the running vehicle by means of a brush of copper 

 wires made to press on the conducting rail. As a rule, only 

 from 50 to 60 per cent of the original power can be utilized when 

 transmitted by electricity, but even this small percentage may 

 be most valuable in certain cases, especially if the original power 

 is obtained from a waterfall which would otherwise go to waste, 

 such, for instance, as the electric tramway at Portrush. 



Another method tor making use of electricity for motive 

 power is by using accumulators or storage batteries. The 

 objection to these at present is their weight and size, but I 

 believe there is a great future for the employment of storage 

 batteries, and it would not surprise me to find the tramcars of 

 Belfast and other towns propelled by electricity before many 

 years pass by. Storage batteries are of immense service where 

 temporary stoppages of the machinery occur, or for the regu- 

 lation of the light when the power is of a fluctuating nature ; 

 also, where a few lights are required to be kept in operation all 

 night. 



The lecture was illustrated by numerous photographs thrown 

 on a screen by dissolving lanterns, operated by Mr. R. W. Welch. 

 Not only were there diagrams for shewing the special parts of 

 the machines, but the various types of the leading dynamos of 

 different construction were illustrated. The experiments, named 

 by Mr. Greenhill in the early part of the paper, were most 

 successfully carried out. 



At the conclusion, on the second evening, Prof. Everett, F.R.S., 

 in proposing a vote of thanks, said, that he felt great pleasure 

 in presiding that night, and he was very much pleased that the 

 lecture had been repeated, as it gave him and others who were 

 not present on the first evening, an opportunity of hearing it on 

 the second occasion. He had to congratulate Mr. Greenhill for 

 the lucid explanations of what some might think rather complex 

 matters, and for the successful way in which the experiments 



