Testing may be done by means of an ordinary candling device such as is used with hens' eggs, each egg being examined separately.
"Ducks and Geese"
Harry M. Lamon Rob R. Slocum
To save time a piece of apparatus may be used which is simple in construction and which simplifies the process of candling considerably.
"Ducks and Geese"
Harry M. Lamon Rob R. Slocum
First grade that can be separated by candling, corresponding to about twenty-four hours of incubation.
"The Dollar Hen"
Milo M. Hastings