142 



HABITS OF BIRDS. 



Egg-frame. 



that the chief point to be attended to was to keep 

 the eggs properly warm by the heat of the dung, 

 without being exposed to the vapour exhaled from 

 it, which pervaded the pores of the shell and became 

 fatal to the embroyo. 



" With this view I caused one of those casks, 

 called half-hogsheads, to be sunk into the bed of 

 dung, after having had a hole dug large enough 

 for its admission, taking great care to have the edges 

 raised three or four inches above the surface of the 

 hot-bed. The top alone had been previously con- 

 verted into a moveable lid by means of cross-bars, 

 and one large and eight smaller holes were made in 

 it and bunged with corks, to serve as regulators of the 

 temperature within. The eggs were let down into 

 the casks in round baskets, about two inches in diame- 

 ter less than the cask, some being deep and others shal- 

 low, the former containing two and the latter one layer 

 of eggs. I caused three of these baskets to be placed 

 in the oven, which contained about two hundred eggs, 

 in such a manner that the lowest was some inches 



