THE ELECTRIC LIGHT. 
37 
these people are several eminent scientists, whose efforts are not 
likely to be misdirected. 
Among the more recent developments of electric lighting is 
the electric light of Mr. Van der Weyde, ordinarily utilised by 
him for photographic purposes, to which he was the first to apply 
it. It is not the production of the current nor the means of 
converting it into light at which Mr. Van der Weyde has laboured 
so much as the rendering of the light produced available as an 
illuminator without wasting it, so to speak, and yet without 
throwing the rays directly upon the object to be illuminated. 
His apparatus and arrangements may be described as follows : — 
In the basement of the house is an Otto silent gas engine of 
eight-horse power, which works steadily and well and without 
needing any attention, save at starting and stopping, goes on 
hour after hour driving either one or a pair of Siemens’ dynamo- 
electric machines, as may be required, the machines producing 
continuous currents. The current thus produced is led up to 
the burners which are placed in the various studios, and which 
consist of two carbon rods placed vertically one over the other, 
the light being produced between the points. The upper rod is 
three- eighths of an inch in diameter, and the lower one three- 
quarters of an inch, and these are placed near the mouth of a 
concave reflector lined with white material. None of the rays 
of light reach the spectator direct ; they are intercepted by a 
disc of opal glass about four inches in diameter. The whole 
body of the rays is gathered up in the reflector and thrown out 
in a flood of pure white light, in which the most delicate shades 
of tint are distinctly discernible. At present the consumption 
of the carbons is followed up by hand-adjustment, that being 
most convenient for photographic purposes. For general illu- 
mination, however, Mr. Van der Weyde proposes a mechanical 
arrangement. In fact, it does not affect his principle whatever 
apparatus for burning he uses ; he can take the Serrin or the 
Siemens lamp, the Jablochkoff candle, or any other suitable 
arrangement. His principle consists in cutting off the direct 
rays from the objects to be illuminated, and surrounding them 
only with a white cloud of light. Mr. Van der Weyde is now 
engaged in a modification of his system, which will shortly be 
seen in an improved form in Regent Street. As regards expense, 
we have here some exact data afforded by the six hours during 
which the light was publicly exhibited on November 9. Long 
use of the Otto gas engine has shown Mr. Van der Weyde that 
the cost of the gas for it is exactly 6c?. per hour. A pair of car- 
bons costs 2s. 6c?., and a pair was consumed during the experi- 
ment. This gives a total of 5s, 6c?., or exactly 11c?. per hour per 
light. But it is to be observed that during the experiment the 
second machine was at times running, so that some deduction 
should be made on that account. In fact, only half the power — 
i 
