FACTS OBSERVED IN HATCHING. 141 



as well as they would have grown and been formed 

 if the eggs had been kept all the time under a hen, 

 there appeared to be sufficient hope that, by re- 

 doubling my attention, I might afterwards fully 

 succeed. I therefore put some fresh eggs into the 

 same oven, continuing every day to put in the eggs 

 laid by my own hens, taking the precaution to write 

 the date upon each. But I was again disappointed, 

 several of them giving evidence of being tainted as 

 early as the twelfth day. 



" Upon resuming my experiments the following 

 November, I caused chicken-ovens to be constructed 

 of different forms, one after another, some in the 

 form of a baker's oven ; but these not appearing to 

 suit, I reverted to my first plan, and had one con- 

 structed in the month of February in a stable large 

 enough to contain six horses. When the temperature 

 had risen to the proper degree, I put in the eggs. 

 The dung of the bed was very moist, and the season 

 being ill suited to dry it, the inside of the oven, when- 

 ever the cover was taken off, was seen to be filled 

 with a thick foggy vapour, so very considerable that 

 the eggs were continually bedewed with it as if 

 sprinkled with water. Some of the eggs were laid 

 in open boxes, having sand strewed over the bottom, 

 which was converted by this moist vapour into a sort 

 of mire. But though the eggs in this mire were 

 nearly as moist as if they had been plunged in water, 

 the embryos continued to be developed till the 

 seventh day, beyond which none of them lived. 



4< The sides of this oven, however, at length be- 

 came dry, and no perceptible vapour remained, yet 

 all my trials with it during two months and a half 

 proved equally abortive, though I was daily imagin- 

 ing and endeavouring to obviate the causes of the 

 failure. After many such trials, enough to wear out 

 the most enduring patience, I at last clearly perceived 



