INCUBATION AND BROODING 343 
the machine under the eggs, but at the top over them. 
This heat must be stable. When a hen is brooding her 
temperature is about 104 degrees. The successful incu- 
bator must be capable of developing a top heat of 104 
degrees to the eggs and keep it steadily at that point. 
While it is true that eggs under a hen vary in tempera- 
ture according to position, they are changed in the nest 
INCUBATOR CELLAR 
Showing the incubators in place. 
from time to time by the hen, as every farm boy knows, 
thereby, on an average, ranging from 102 to 103 degrees. 
Each machine must also possess sufficient ventila- 
tion, Fresh air is a perpetual necessity. Moisture is 
essential in successful incubation, but a saturated atmos- 
phere is not wanted. The idea is to replace what has 
been evaporated through the machine. 
Every reputable maker of incubators sends out instructions with 
his machine, and the purchaser should follow these implicitly. If 
he does not, he is running a risk. The instructions sent out with 
any machine are the result of experience with that particular make, 
and as the manufacturer’s interest lies in obtaining satisfactory 
hatching, so the directions are to that end and should be valued. 
