46 ARTIFICIAL HATCHING. 



through the means of fire, or stable-dung ; we made 

 choice of the former. A number of eggs, wrapped 

 in wool, and covered in flannel, in a common wicker- 

 bottom sieve or riddle, were suspended over a chaff- 

 ing-dish of charcoal, in a chimney where was no 

 other fire. The chimney-skreen was constantly kept 

 fast, in order to concentrate the heat. It was a 

 small chimney, into the funnel of which the wind 

 did not set with any force, at least at that time, and 

 the heat was well retained as in a stove. We had no 

 thermometer, but measured the degree of heat 

 merely by our own feeling, and as we could judge 

 it to correspond with the natural heat imparted by 

 the body of the hen during incubation. Reaumur 

 determined the proper degree of heat to be thirty- 

 two degrees by his thermometer, about one hundred 

 of that of Fahrenheit. Constant attendance, at 

 least every three or four hours, must obviously be 

 necessary, both night and day, to preserve an equal- 

 ity of heat to both sides of the eggs, of which there 

 was only one layer, filling the bottom of the sieve, 

 to the number of forty odd. This was effected by 

 turning the eggs, giving each side the equal chance 

 of nearness to the fire, which must be constantly 

 kept to a moderate and equable heat. We made 

 use of all fine and new-laid eggs, but in our first 

 attempt we lost a number, which however were not 

 rotten, but had evidently bred chickens, that pe- 

 rished from an imperfect disposition of the heat. 

 They were most probably of the eggs placed in the 

 circumference, where the heat might be defective, 

 and which we afterwards had the precaution to 

 change to the centre, where the heat was greatest. 



