NATURAL AND ARTIFICIAL INCUBATION 83 



Attend to the regulation of the temperature of the incu- 

 bator before opening the door of the machine to attend to 

 the eggs, but do not change the regulator any more than is 

 absolutely necessary. The eggs will tend to throw off some 

 heat as the embryo in the egg develops so that this fact may 

 occasionally make it necessary to change the regulator 

 slightly. The temperature in the egg chamber may Ukewise 

 be regulated by lowering the flame of the lamp in the mid- 

 dle of the day when the room is warmer, owing to outside 

 heat. Incubators require careful, regular, and sys- 

 tematic attention, which, though simple, is very ex- 

 acting in order to secure good hatches. 



The correct temperature. This depends upon the posi- 

 tion of the thermometer in the egg chamber. The manu- 

 facturers' directions should be followed in this connection 

 and changed only after experience shows that they can be 

 improved. When the contact thermometer is used, the 

 temperature should be held at 1013^° to 102° F. the first 

 week; 102° to 103° the second week; and 103° the third 

 week. When a hanging thermometer is used, the tempera- 

 ture should be 102° to 1023^° F. the first two weeks, and 

 103° F., the last week. When the hatch is complete the 

 thermometer will frequently run up to 104° or 105° F. with- 

 out any injury to the chicks. This is due to the increased 

 heat from the bodies of the chicks. It is not advisable to 

 change the regulator at this time, provided the temperature 

 does not run beyond 105° F. With a good hatch the eggs 

 will usually start to pip on the evening of the 19th day 

 or the morning of the 20th and most of the chicks will be 

 out of the shell on the morning of the 21st day. A high 

 temperature during the incubation period may hatch the 

 eggs too quickly and produce weak chicks, while a tem- 

 perature that is too low throughout the hatch may delay 

 the hatch somewhat. 



