UTAH ACADEMY OF SCIENCES 167 
SOME PROBLEMS IN DAYLIGHT 
ILLUMINATION. 
BY C. ARTHUR SMITH. 
(Abstract). 
Only two of the many problems of daylight illumin- 
ation were taken up in this investigation, viz. Daylight. 
Factor and Distribution. 
The work was mainly carried on at the Liberty 
school during the summer and fall of 1918. This build- 
ing was selected because of the ideal conditions both as to 
location and architectural design. It is free from obstruc- 
tions, natural and artificial. All rooms except those in 
the four corners of the building are unilaterally lighted. 
The corner rooms are bilaterally lighted. The desks 
are arranged in rows parallel to the windows. The exter- 
nal walls of the rooms are mainly occupied by windows 
which extend from about 18 inches above the tops of the 
desks to within about 2 inches of the ceiling. The walls 
are finished in light cream and the window shades are a 
light tan. 
The daylight factor, i. e. the per cent of light indoors 
to that out of doors, was found to be independent of the 
time of day, of the season of the year, and of atmospheric 
conditions. That is to say, any change in outside illumin- 
ation produces an exactly corresponding change inside. 
It differs, however, in different places, even in different 
places in the same room. For unilaterally lighted rooms, 
the variation from the row of desks nearest the windows 
to that farthest away is shown by the curve, fig. 1. 
For bilaterally lighted rooms, the change in daylight 
factor in different parts of the room are not regular, i. e. 
taking rows of desks along either side of the room in 
which the windows are situated, it is found that the day- 
light factor does not diminish regularly to the far side 
