INCUBATION 
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Most people have an exaggerated idea of the hen’s success 
as a hatcher. I have a number of records of hen hatching 
with large numbers of eggs set, and they are all between 55 
per cent. and 60 per cent. The reasons the hen does not hatch 
better are as follows: 
First: Actual infertile eggs—usually, running about 10 per 
cent. in the best season of the year. 
Second: Mechanical breakage. 
Third: Eggs accidentally getting chilled by rolled to one side 
of the nests, or by the sick, lousy or crazy hens leaving the 
nests or standing up on the eggs. 
Fourth: Eggs getting damp from wet nests, dung or broken 
eggs; thus causing bacterial infection and decay. 
The last three causes are not present in artificial incuba- 
tion. From my observation they cause a loss of 15 per cent. 
of the eggs that fail to hatch, when hens are managed in large 
numbers. This would properly credit our hens with hatches 
running from 70 per cent. to 75 per cent., which, for reasons 
later explained, is not equal to hatches under the best known 
conditions of artificial incubation. 
The assumption that the hen is a perfect hatcher, even 
barring accidents and the inherited imperfection of the egg, is 
not, I think, in harmony with our general conception of nature. 
Not only are eggs under the hens subject to unfavorable 
weather conditions, but the hen, to satisfy her whims or hun- 
ger, frequently remains too long away from the eggs, allowing 
them to become chilled. 
For directions of how to manage setting hens, consult the 
Chapter on “Poultry on the General Farm.” 
The Wisdom of the Egyptians. 
Up to the present there have been just three types of arti- 
ficial incubation that have proven successful enough to war- 
rant our attention. These are: 
First, the modern wooden-box-kerosene-lamp incubator which 
is seen at its best development in the United States. 
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