48 
The Illustrated Book of Poultry. 
provided. She should then be brought at night, in a comfortable basket, entirely shut in so as 
to be dark, with a nest-egg under her, and placed on the nest by candlelight ; or still better, put 
down in front where she can see the nest-eggs, and be allowed to walk in herself ; then shut in 
securely. Next morning, her food being provided before, she should be unfastened and allowed 
to come off herself, and to find her own way back. Not till she has thus found her own way 
twice should the eggs be trusted under her, when there will hardly ever be a failure. 
At the expiration of from six to eight days the eggs should be examined by candlelight, as 
the unfertile ones can then be easily detected, and if the greater part be sterile time is saved, as 
the same hen may be at once set again. A new-laid egg, as is well-known, appears clear and 
translucent when held between the eye and a candle. Barren eggs appear so still (as shown in 
Fig. 26), even after being sat upon for a week ; but the eggs which contain embryo chickens then 
Barren Egg. Fertile Egg. 
Fig. 26. 
have a dark shadow in the centre, shading off to more transparency at the edges. The amount of 
shadow will vary with the time of incubation and size of the eggs, and perfect opacity will not be 
found till nine or ten days have elapsed, even with good-sized eggs ; but after a few experiments, 
enclosing the egg between the thumb and forefinger, and turning the rest of the hand so as to 
shade the light as much as possible, no mistake will ever be made, and by degrees, even with the 
hand alone, the quality will be determined with certainty at the fifth day. By using a plate of 
tin or zinc, to shade the light, and holding the egg to an aperture in it, cut to the shape, Lhe light 
may be brought closer, and the difference known at the fourth day; and by employing a more 
perfect apparatus (shown at Fig. 27), where the light of the lamp A is strongly thrown by the 
reflector B and lens C full upon the egg at E, and all other light excluded, fertile eggs can be 
known even at the end of thirty-six hours (some say twenty-four), the minute blood-vessels which 
begin to form round the germ being clearly visible. The sterile eggs up to about eight days are 
perfectly good for culinary purposes ; and if withdrawn at the end of the second day will not 
