EGG-DRILLS. 



37 



for the smallest eggs — even of hummingbirds — and 

 up to warblers, sparrows and those say of a thrush. 

 The grooves forming the drilled surface should be 

 cut with a chisel. The second size will suit the gen- 

 erality of eggs, excepting those of very large birds 

 and of sea-fowl, which usually lay eggs with a strong 



Fig. 3. 



but soft shell. The grooves may be cut either with 

 a chisel or a file, but if with the latter, greater care 

 will be requisite in its use. A third size is intended 

 for the largest eggs, and even some of the smaller 

 ones which have a chalky shell, such as Crotophaga. 

 The grooves are cut with a file; in the manufacture 

 of all these drills the greatest care is necessary that 



