AMERICAN POULTRY CULTURE 
the same age and size, and may all be kept in one 
flock with a great saving in time and labor; and 
machine-raised chicks are decidedly easier to keep 
free from lice. 
It is always best for the beginner to follow 
closely the instructions sent along with the machine 
Instructions he is using, because different makes 
for Operating of machines, different locations, and 
Incubators — different climatic conditions require 
vastly different methods of operation; and the man- 
ufacturer of your machine ought to know better 
than anybody else how to operate it for best results. 
There are, however, a few general principles 
which may be laid down that will hold good with 
every make of machine and in every climate, and 
which sometimes are not found in incubator instruc- 
tion books, even though they are important to one 
who has never had experience. 
Make sure that your thermometer registers ex- 
actly correct. Test it at the beginning of each 
hatching season with a physician’s thermometer. 
This may be done by holding the two instruments 
in a pan of water and stirring gently and steadily 
to keep the temperature of the water uniform. A 
half degree variation in the thermometer may ruin 
a hatch. New thermometers sometimes are imper- 
fect, and old ones will occasionally show a slight 
variation from one season to the next. 
Have the incubator setting perfectly level, as 
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