FACTS OBSERVED IN HATCHING. 139 



experiments with dung in a state of fermentation, an 

 abstract of which may be interesting 1 , were it only to 

 show the importance of certain circumstances to the 

 success of hatching. It is well known to gardeners 

 that beds of fresh dung become hot a few days after 

 they have been made up; and that the heat sub- 

 sequently increases more and more every day till it 

 becomes considerable enough to give pain to the 

 hand, and consequently much stronger than what 

 ought to be employed in hatching. In fact the dung 

 hot-bed used by M. Reaumur almost dressed the eggs 

 and made them fit for eating, though they were in a 

 pot. The heat in question, however, is by no means 

 steady or uniform in temperature, neither is it ever 

 the same at different depths, or in different parts 

 of the same bed. In order to obviate these diffi- 

 culties, this ingenious experimenter conceived the 

 idea of only employing the dung to heat a cavity or 

 oven instead of plunging the eggs into it ; and he 

 began by trying two beds, not so wide as cucumber 

 beds, parted by a narrow path, closed at the ends, 

 and forming an oblong oven or cavity, the air of 

 which was kept warm by the fermentation. The 

 whole was covered in by boards, though not very 

 closely, and the temperature was ascertained by 

 means of thermometers placed in various parts ; 

 and, to shelter it from rain which would have 

 injured the eggs, it was placed in a large coach- 

 house. 



" A few days after it had been constructed," con- 

 tinues the enthusiastic naturalist, " the thermometer 

 informed me that the heat of the oven was much 

 superior to what I wanted ; but as soon as it was 

 reduced to the degree desired I introduced 200 eggs 

 into the oven, enough for a first experiment, though 

 it was large enough to contain above 1000. The 

 greater part of the eggs in question were ranged 



