Incubation 189 



impossible for the poultrymen of modern times 

 to maintain large flocks of young birds for egg 

 production and rear chickens by the natural 

 method. 



AKTIFICIAL INCUBATION 



The art of hatching eggs by means of arti- 

 ficial heat has been known for a long time. 

 Early travelers in Egypt gave accounts of ovens 

 that were used for hatching the eggs of ducks, 

 geese, and chickens. Heat was supplied by fer- 

 menting manure. Remains of these ovens are 

 said to have been seen in comparatively recent 

 times. It is said that the French became inter- 

 ested in artificial incubation as early as the fif- 

 teenth century, but not until the latter part of 

 the eighteenth century was use made of hot 

 water as a means of conveying heat for artificial 

 incubation. From this time until the middle of 

 the nineteenth century, comparatively little ad- 

 vancement was made in the construction of incu- 

 bators. Since 1870 many improvements have 

 been made and a large number of incubators 

 have been placed on the market. 



In the manufacture of the modern incubator, 

 the idea has been largely to imitate nature. As 

 the hen applies heat above the egg, so nearly all 

 incubators apply heat to the egg -chamber from 

 above. In natural incubation the hen provides 



