ECONOMY OF THE ELECTRIC LIGHT.


Mr. W. H. Preece writes to the _Journal of Arts_ as follows:

At the South Kensington Museum, very careful observations have been made
on the relative cost of the two systems, _i. e._, gas and electricity.
The court lighted is that known as the "Lord President's" (or the Loan)
Court. It is 138 feet long by 114 feet wide, and has an average height
of about 42 feet. It is divided down the middle lengthwise by a central
gallery. There are cloisters all around it on the ground floor, and the
walls above are decorated in such a way that they do not assist in the
reflection or diffusion of the light. The absence of a ceiling--the
court being sky-lighted--is to some extent compensated for by drawing
the blinds under the sky-lights.

The experiments commenced about twelve months ago, with eight lamps
only on one side of the court. The system was that of Brush. The dynamo
machine was driven by an eight horse-power Otto gas engine, supplied by
Messrs. Crossley. The comparison with the gas was so much in favor of
electricity, and the success of the experiment so encouraging, that it
was determined to light up the whole court.

The gas engine, which was not powerful enough, was replaced by a
14-horse power "semi-portable" steam engine, by Ransomes & Co., of
Ipswich--an engine of sufficient power to drive double the required
number of lights. The dynamo machine is a No. 7 Brush. There are sixteen
lamps in all--eight on each side of the court. The machine has given no
trouble whatever, and it has, as yet, shown no signs of wear. The