American Agriculturist 
THE FARM PAPER THAT PRINTS THE FARM NEWS 
“Agriculture is the Most Healthful, Most Useful and Most Noble Employment of Man ”—Washington 
Reg. U. S. Pat. Off. Established 1842 
Volume 112 For the Week Ending September 22, 1923 Number 12 
The Factor of Intensity of Light 
A Vital Influence in the Successful Use of Illumination in the Poultry House 
T HE effect of artificial illumination on 
poultry was observed some thirty- 
three years ago and like all discov¬ 
eries was given little attention at the 
time, but during the past ten years pro¬ 
gressive poultrymen have dared to try out 
artificial lighting and the agricultural col¬ 
leges in the United States and Canada have 
carried on extensive experiments which 
have proved that the judicious use of ar¬ 
tificial light does increase the winter egg 
production, that the use of lights for this 
purpose is profitable 
and that no ill effects 
are produced on the 
birds. 
This may seem a 
sweeping statement, 
but all the great mass 
of evidence which has 
been obtained by ex¬ 
tensive experimenta¬ 
tion proves that the 
use of lights alone will 
not produce desirable 
results, but that the 
proper care and feed¬ 
ing methods combined 
with the use of lights 
produces greater egg 
production during the 
winter or short day 
season. 
It is sometimes er- 
roniously assumed 
that the use of lights 
causes the birds to pro¬ 
duce more eggs .per 
year. The number of 
eggs per year that the 
bird produces depends 
on other things, one of 
which is the breeding. 
The real benefit from 
the use of lights is to 
lengthen the working 
day during the high- 
price egg period, and 
to get/a more uniform 
production during the 
laying period of - the 
bird. This better dis¬ 
tributes the labor of caring for the flock and 
due to the variation in the price of eggs 
makes it possible to maintain the flock 
through the winter at a profit. 
The factors of the length of day to give 
the birds and the feeding practice under 
artificial light have been pretty well de¬ 
termined and information on this is available 
at all the agricultural colleges, but the factor 
of the intensity of light in the pen to pro¬ 
duce results had not been given serious at¬ 
tention until the New York State College of 
Agriculture at Ithaca commenced investiga¬ 
tions some two years ago to determine if 
possible, first, the intensity of light on the 
floor of the poultry house which would enable 
the birds to see and pick up the grain readily 
and second, the most economical means of 
securing this intensity. 
By F. L. FAIRBANKS 
The arrangement of the test pen is shown 
in Figure 1. Two lines of stakes at right 
angles were set along the floor the zero point 
of each line directly under the light. Many 
different reflectors, sizes of lamp and heights 
from the floor were used and in each case 
the intensity of light on the floor at each 
stake was measured by a foot-candle meter. 
In this way charts of the floor intensity were 
obtained. Then the birds were allowed to 
work under these different combinations of 
lamp, reflector and height from the floor, 
until it was determined that below a certain 
intensity the birds feed slowly or as it was 
termed, the birds were inactive. The ac¬ 
tivity increased up to a certain intensity and 
above this intensity no increase in activity 
was obtained. This intensity for active feed¬ 
ing was from eight-tenths to one foot-candle. 
It was also found that other factors than 
the intensity of light on the floor had a very 
noticeable effect on the activity of the flock. 
One of these factors was the general illumi¬ 
nation of the pen and by general illumina¬ 
tion is meant the intensity of light on the 
floor, the walls, the perches and the ceiling. 
Please for a moment consider how the 
break of day rouses the birds. As the day¬ 
light increases it floods the perches and the 
floor with light. The walls above the perches 
and the ceiling are of course illuminated. 
But the point is that the light comes directly 
to the birds eyes. The bird dqes not look 
above the light, it looks into it and down to 
the ground under it where the food is found. 
The conditions with artificial light are 
somewhat the same. The arrangement in 
Figure 1 is such that the light goes directly 
to the birds on the perches and causes them 
all to come down to feed. The arrangement 
in Figure 2 does not permit direct light to 
strike the perches and 
it was found by re¬ 
peated trial that some 
of the birds tended to 
stay on the perches. 
These two examples 
also show a difference 
in feeding area with 
the same size of lamp, 
Figure 1 giving the 
greater feeding area 
with the same ex¬ 
penditure of electric 
energy. 
A great number of 
interesting facts were 
observed in these ex¬ 
periments, but it is 
not possible to discuss 
them fully here, how¬ 
ever the outstanding 
features are: 
1. An intensity of 
light of from eight- 
tenths to one foot- 
candle is the intensity 
which permits active 
feeding. 
2. The perches 
should have direct 
light from the lamp so 
that all the birds will 
come down to feed. 
3. The economical 
lamp which will give 
this intensity is a 
forty watt Mazda. 
4. The reflector 
which gives the widest 
workable distribution 
is cone shaped, sixteen inches in diameter 
by four inches high, the reflecting surface 
being aluminum bronze. 
5. White-wash on the walls and ceiling 
have a decidedly detrimental effect with 
the use of artificial light. 
6. The general rule for finding the num¬ 
ber of lighting units, (one 40-watt Mazd^ 
lamp with 16 by 4-inch reflector,) for a 
given size of pen, is to divide the number 
of square feet of floor space by 200. The 
nearest whole number will be the number 
of lamps required. 
7. Locate these units six feet from the 
floor, ten feet apart and along a line mid¬ 
way between the front of the house and the 
front of the dropping board. 
8. Where a long house is divided into 
(Continued on page 203) 
Figure 1. With a shallow reflector, the more desirable, the light goes directly tq the birds on the 
perches, causing them to come down and feed 
