1402 



The Cornell Reading-Courses 



A temperature higher than 105° and one lower than 103" should be 

 avoided at this time. Both of these undesired extremes will occur at some 



time during the hatching period unless careful 

 provision is made against them. It would be 

 much better to remove the lamp for a time 

 than to permit the great increase in temperature 

 that usually occurs when the hatch is at its best. 

 Generally, this increase may be overcome by turn- 

 ing down the lamp flame. Very often toward 

 , the end of the hatching period it is necessary 

 to raise the 

 flame in order ^, . - -^ 



to- keep the 7 ..^^^^ "' ~^^\^ 1^ 



required tem- ■ ij 



perature. •' 

 Fig. 38. — Various positions rr>i , 



of air cells These two 



changes in 



temperature in so short a time will 



be readily understood when it is 



remembered that the eggs supply 



a great amount of animal heat 



during the last week of incubation, 



and that this animal heat naturally 



increases as the chickens commence 



to work their way out of the shells. 



After the chickens are all hatched 



and have dropped into the nursery, 



the heat decreases. There is also 



more or less condensation of mois- 

 ture from the newly-hatched chick 



at this time, and this has a tendency to lower the temperature. 

 The position of the ventilators at hatching time depends on the make of 



the incubator. It is not considered 

 advisable to permit a very great 

 change of air until the chickens are 

 all out. After the hatch is completed 

 the egg trays should be removed, 

 together with any eggshells that may 

 have dropped into the nursery, and 

 the ventilators should be opened full 



width. If the room is warm the incubator door may be fastened open 



one half inch at the top. 



Fig. 39. — Size of the air cell at different 

 periods of incubation: i day, 7 days, 

 14 days, and ig days of incubation 



Fig. 40. — A serviceable box for moving 

 chicks frorft the incicbator to the brooder 



