Chapter XXXIX. 



AETIPIOIAL I3Sra"CnB-&-TXO:fcT_ 



Artificial Incubators in Ancient Times — Progress in Invention of Incubating 

 Machines — The Graves Incubator — Halsted's Automatic Incubator — 

 The Boyle Incubator — Tomlinson's Automatic Incubatob — Thermostatic 

 Incubator — Hbabson's Regulator. 



ARTIFICIAL incubation has been practiced in Egypt and China 

 for thousands of years. The profession was hereditary, and 

 the secrets of the successful processes" descended from father 

 to son, and were guarded with religious sacredness. 



The fertile eggs of all animals will produce their kind if they have 

 the requisite amount of heat, moisture, and air. The different ani- 

 mals have many ways of development from the egg. Some snakes' 

 eggs hatch while in the cold ground ; some eggs are incubated in the 

 water ; others again are hatched m the body, and still others in N the 

 sun-heated sand, as in Egypt, or in the warm earth, as in other trop- 

 ical countries. 



One of the greatest difficulties to be overcome in artificial incu- 

 bation in the temperate latitudes is the regulation of the heat sup- 

 ply, an obstacle easily surmounted by the ancient nations in their 

 warm climates. . v The hen supplies a certain amount of heat and 

 moisture, admirably regulated by nature, and adjusted to the pur- 

 pose of developing the life-principle in the egg into the organized 

 chick, through the process of incubation. The problem in artificial 

 incubation is to supply, in the requisite degree, this heat and moist- 

 ure, and to preserve and regulate the temperature and state of the 

 atmosphere so as to reproduce, as nearly as possible, the conditions 

 of the process as carried on by nature herself. On the deserts of 

 Africa the Arabs hatch out eggs in the hot sand with great success, 

 the heat being of just that even temperature required for the pur- 

 pose. 



In the process of investigation into the methods of producing 

 artificial heat, there have been invented large numbers of incubating 

 machines in all countries, but until within a very few years the in- 

 tricacy of their mechanism and their expensiveness have prevented 

 their extensive adoption. In our own day their simplicity of con- 



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