was £475. The number of lamps in use is 187, and the cost for the year 1896 was 190, as compared with a gas bill for the year 1891 of £95. The difference in cost, however, must not be closely compared, for several rooms are now used by the public which were not in use in 1891. It is estimated that the gas bill for the whole building would now be about £150.
In both these cases it will be seen that the electric current is obtained from a company. Some libraries, such as the British Museum, manufacture it for themselves. The experience of the Mitchell Library, Glasgow, which does this, is that the wages of engineer, and cost and repairs of plant, gas for engines, &c., amount to £350 yearly for an installation of 274 lights. This experience, and similar results elsewhere, seems to prove that only in very large libraries is it cheapest to produce the light if it can be purchased at anything below 8d. per unit. It may also be mentioned that if it is decided to make your own light, the machinery for doing so should be placed in a separate and detached building away from the library. If the works are placed in the basement, they will be found to be a nuisance from the vibration and noise caused by the working of the engines.
The system of lighting best adapted for libraries is that of a plentiful supply of 8 candle-power lamps, or larger, for the reading-tables, each provided with a separate switch, so that it can be turned off when not in use. For large and lofty rooms there should be provided, in addition, two
