CHAPTER V. 



Artificial Incubation. 



The Chinese and Egyptisins have, for fhousands of years, had the secret of 

 hatching eggs without the intervention oi the hen. Indeed, it would seem al- 

 most a matter of course that the inhabitants of tropical countries should early 

 have learned this art, from watching the method by which i^e eggs of turtles, 

 alligators, etc., are incubated, being simply buried in the warm sand of the river's 

 bank. As early as 1750 the French scientist, De Eeaumur, perfected a process 

 of artificial incubation, which, though successful, was not practicable for ordi- 

 nary purposes. During the past twenty years, hqivever, the attention of poul- 

 terers has been freshly drawn to this questiori, and now the number of appliances 

 for artificial incubation bids fail' to equal the patent bee-hives. 



The essentials of a successful incubator are three : an equable heat of about 

 105 degrees ; sufficient moisture in the atmosphere to prevent an undue evapora- 

 tion from the egg ; and ventilation. These conditions are obtained by the Egyp- 

 tians and Chinese through the use of large ovens, which are watched day and 

 night by skilled attendants. De Beaumur, in his investigations upon this sub- 

 ject, first used ovens, but unsuccessfully; his final success was obtained by the 

 use of fermenting horse manure, and that material is still employed in at least 

 one of the processes used to-day. It is not a pleasant material to handle, how- 

 ever, and does not give that opportunity for frequent insp^tion of the eggs 

 which is desirable, hence numerous attempts have been made to revive the more 

 ancient processes, with such modifications as are demanded by our age of steam 

 and lightning, and especially to provide an automaton whiqh shall raise the.flame 

 of the lamp when the mercury in the egg-drawer begins to fall, and lower it 

 if the heat becomes too great. This is the problem which has vexed the soul of 

 many a Yankee during the past two decades. 



It has been found that the mercury may rise to HO degrees without injury to 

 the eggs, provided it does not remain at that point more than a very few minutes, 

 or it may sink as low as 50 degrees, for a correspondingly short time ; but should 

 it remain below 100, or above 106 for many hours, all the labor expended upon 

 the lot of eggs which the incubator may then contain wiU. have been thrown 

 away, while, as will be seen, it requires a very delicate instrument to quickly 

 appreciate the difierenoe between these degrees of heat. Electricity, that most 

 sabtile of aU the powers of nature whose aid man has learned to invoke, has 

 been naturaUy the first thought of many for this work, and numerous machines 

 have been constructed with electrical appliances attached, so arranged in con- 

 nection with instruments for the measuring of heat that a very slight change in 

 the temperature of the drawer containing the eggs will cause machinery to be 



