22 
Ordinary Meeting, November 26th, 1878. 
J. P. Joule, D.C.L., LL.D., F.R.S., &c., President, in the 
Chair. 
“On some Improved Methods of Producing and Regu- 
lating Electric Light,” Part II., by Henry Wilde, Esq. 
In a former communication to the Society, I directed 
attention to the fact, that when the electric light is pro- 
duced from the ends of two carbon pencils placed parallel 
to each other, if the strength of the electric current, the 
thickness of the carbons, and the distance between them 
are rightly proportioned, the carbons will burn steadily 
downwards until they are wholly consumed, without any 
insulating material between them. To initiate the light by 
this method, it is necessary to complete the electric circuit 
between the carbons by means of some conducting sub- 
stance, which volatilises on the passage of the current, and 
establishes the electric arc between the points. 
When a number of such lights are produced simulta- 
neously from the same source of electricity, any interrup- 
tion in the continuity of the current extinguishes all the 
lights in the same circuit, and each pair of carbons requires 
to be reprimed before the lights can again be established. 
This defect, as will be obvious, would cause great inconve- 
nience when the lights are not easily accessible, or are at 
considerable distances apart. 
In the course of my experiments it was observed that 
when the electric circuit was completed at the bottom of a 
pair of carbons close to the holders, the arc immediately 
