136 The Hen at Work 



air is sweet and fresh about an incubator, and the 

 operator can usually tell by the "feel" whether 



The fresh egg has a small air space as shown at the top. The 



second Hne shows the larger air space after one week of 



evaporation, the third line after two weeks, and the 



lower line shows the air space the chick 



will have at hatching time 



the atmosphere is damp or dry. It should have 

 a distinct feeling of dampness. 



If the air seems too dry, there are several devices 

 for supplying sufficient moisture. 



