270 THE LIFE OF A BIRD. 



precise way is, to look at them by the light of a 

 candle ; if quite fresh, there are no spots upon the 

 shells, and they have a brilliant light-yellow tint." 

 This important point, more important in artificial 

 incubation even than in culinary affairs, having been 

 attended to, the eggs are placed in the incubator, 

 and the process commences. The eggs are gently 

 moved three times in the twenty-four hours, by 

 which the slight displacement affected by the hen 

 in leaving and returning to her nest is imitated. 

 This action appears necessary, it is said, to obviate 

 adhesion to the shell, and to permit of the minute 

 blood-vessels ramifying with greater freedom over 

 the surface of the egg; but on these points our 

 information requires to be confirmed. The stove 

 which supplies the machine with heat, contains a 

 sufficient supply of fuel when fully charged to 

 last the twenty-four hours. When once lighted 

 it consequently requires but a small degree of 

 attention. About mid-day daily, the eggs are 

 taken out and cooled, for about twenty minutes. 

 This is also in imitation of the hen, which is known 

 to leave her nest every day in search of food for 

 twenty minutes or half an hour. It is supposed 

 that in this way a certain degree of aeration is 



