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COMMERCIAL POULTRY RAISING 



providing either extreme is discovered and corrected. These 

 temperatures might be termed the limits of natural incubation. 

 Some operators prefer to start a hatch at 102 degrees, and grad- 

 ually allow it to creep up to 1033^ degrees at the close. 



Hen's Temperature. — Personally, I think there is no better 

 authority than an imitation of the hen's ways. If we insert a ther- 

 mometer under a sitting hen we will find a temperature of 104^ de- 

 grees against her bare breast ; in her plumage in about the center of 

 the nest the temperature is a trifle more than 103 degrees; while 

 the temperature inside the sitter's wings, a position that corre- 

 sponds to the outside row of eggs, is about 100 degrees, sometimes a 



little less. Thus, the eggs are 

 exposed to a constant vari- 

 ation in temperature, with an 

 average of 1 02 >^ degrees. The 

 hen turns her eggs about eight 

 times daily in order to over- 

 come this variation, but it 

 cannot be doubted that some 

 eggs will remain in the 

 warmest part of the nest for a 

 greater length of time, no 

 matter how faithful and care- 

 ful the hen may be. 

 Thermometer. — Notwithstanding the existence of this varia- 

 tion, it should not be construed to mean that the office of the 

 thermometer is unimportant. The thermometer should be 

 absolutely accurate, since it is only by this instrument that the 

 operator can attempt an average temperature. We have shown 

 where a variation of a degree or so will not seriously affect a 

 hatch, if it is shortly corrected, but if the temperature varies a 

 degree or even a half degree for the entire period, it will make a 

 big change in the hatch. 



There are two general styles of incubator thermometers, while 

 each style has numerous modifications. One is mounted on a 

 metal frame and placed on the egg tray, with the bulb located 



[(Courtesy Buckeye Incubator Company) 



Fig. 151. — Incubator tray. showing the 

 relation of thermometer to the eggs. 



