16.1 11.9
February 10.0 10.5
March 7.6 8.8
April 6.1 6.9
May 5.2 5.8
June 3.8 5.9

The figures in one column have no direct relation to those in the other;
that is, each column must be considered by itself. It is seen from the
foregoing that about half the number of the accidents due to poor
illumination occurred in the months of November, December, January, and
February. These are the months of inadequate illumination unless
artificial lighting has been given special attention. The same general
type of seasonal distribution of accidents due to other causes is seen
to exist but not so prominently. The greatest monthly rate of accidents
during the winter season is nearly four times the minimum monthly rate
during the summer for those accidents due to lighting conditions. This
ratio reduces to about twice in the case of accidents due to other
causes. Looking at the data from another angle, it may be considered
that the likelihood of an accident being caused by lighting conditions
is about twice as great in any of the four "winter" months as in any of
the remaining eight months. Doubtless, this may be explained largely
upon the basis of morale. The winter months are more dreary than those
of summer and the workman's general outlook is different in winter than
in summer. In the former season he goes back and forth to work in the
dark, or at best, in the cold twilight. He is not only more depressed
but he is clumsier in his heavier clothing. If the enervating influence
of these factors is combined with a greater clumsiness due to cold and
perhaps to colds, it is not difficult to account for this type of
seasonal distribution of accidents. A study of the accidents of 1917
indicated that 13 per cent. occurred between 5 and 6 P. M. when
artificial lighting is generally in use to help out the failing
daylight. Only 7.3 per cent. occurred between 12 M. and 1 P. M.

[Illustration: SIGNAL-LIGHT FOR AIRPLANE]

[Illustration: TRENCH LIGHT-SIGNALING OUTFIT]

[Illustration: AVIATION FIELD LIGHT-SIGNAL PROJECTOR]

[Illustration: SIGNAL SEARCH-LIGHT FOR AIRPLANE]

[Illustration: UNSAFE, UNPRODUCTIVE LIGHTING WORTHY OF THE DARK AGES]

[Illustration: THE SAME FACTORY MADE SAFE, CHEERFUL, AND MORE PRODUCTIVE
BY MODERN LIGHTING]

There is another aspect