conditions.

[Illustration: LOCOMOTIVE ELECTRIC HEADLIGHT]

[Illustration: SEARCH-LIGHT ON A FIRE-BOAT]

[Illustration: BUILDING SHIPS UNDER ARTIFICIAL LIGHT AT HOG ISLAND
SHIPYARD]

Although it is difficult to present figures in a brief discussion of
this character, it may be stated that, in general, the cost of adequate
artificial light is about 2 per cent. of the pay-roll of the workers;
about 10 per cent. of the rental charges; and only a fraction of 1 per
cent. of the cost of the manufactured products. These figures vary
considerably, but they represent conservative average estimates. From
these it is seen that artificial lighting is a small factor in adding to
the cost of the product. But does artificial lighting add to the cost of
a product? Many examples could be cited to prove that proper artificial
lighting may be responsible for an actual reduction in the cost of the
product.

In a certain plant it was determined that the workmen each lost an
appreciable part of an hour per day because of inadequate lighting. A
properly designed and maintained lighting-system was installed and the
saving in the wages previously lost, more than covered the
operating-expense of the artificial lighting. Besides really costing the
manufacturer less than nothing, the new artificial lighting system was
responsible for better products, decreased spoilage, minimized
accidents, and generally elevated spirits of the workmen. In some cases
it is only necessary to save one minute per hour per workman to offset
entirely the cost of lighting. The foregoing and many other examples
illustrate the insignificance of the cost of lighting.

The effectiveness of artificial lighting in reducing the cost of living
is easily demonstrated by comparing the output of a factory operating on
one and two shifts per day respectively. In a well-lighted factory which
operated day and night shifts, the cost of adequate lighting was 7 cents
per square foot per year. If this factory, operating only in the
daytime, were to maintain the same output, it would be necessary to
double its size. In order to show the economic value of artificial
lighting it is only necessary to compare the cost of lighting with the
rental charge of the addition and of its equipment. A fair rental value
for plant and equipment is 50 cents per square foot per year; but of
course this varies considerably, depending upon the type of plant and
the character of the equipment. An inves