A GUIDE FOR KEEPERS OF POULTRY 213 
ditions of natural incubation. In this case the excessive 
evaporation is undoubtedly due to the dryness of the air 
in the incubators, because the drier the air the more mois- 
ture it will take from the eggs just as more water will 
be evaporated from a wet bulb thermometer.’ 
“As a climax to this very careful and extended series 
of experiments under varying conditions the best en- 
dorsement of our own discoveries is unknowingly given 
in relating facts as they were found from actual experi- 
ence. Speaking of sand as a means of supplying mois- 
ture the bulletin says: ‘To show the difference in evapo- 
ration from a tray of sand and a pan of water, incubator 
No. 6, set June 1, was provided with a tray of water in- 
stead of sand. The tray was the same as used in the 
other machines. The loss of weight in the eggs in this 
machine was 16.13 per cent as against an average of 12.28 
per cent for the maximum moisture machines where sand 
was used. The sand is therefore more effective as an 
evaporating surface than water.’ ” 
Profs. Graham and Dryden and Mr. Nix are probably 
the highest authorities we have on artificial incubation, 
Profs. Graham and Dryden making their experiments in 
the line of their duties in connection with the experiment 
stations to which they are attached, and Mr. Nix for his 
own benefit as a manufacturer of incubators. It will be 
seen that all of them agree that moisture is necessary to 
the best results in artificial incubation. However, it is 
but justice to add that we have used two non-moisture 
machines with perfect satisfaction and the chicks hatched 
from them were healthy and vigorous and grew to matur- 
ity with no more than the normal loss. These machines 
were used within two miles of Lake Michigan where the 
atmosphere is naturally humid and the conditions favor- 
