We all know that heat ascends. As long as the 

 air in the egg chamber is warmer than that outside, 

 the heat of the egg chamber will seek an outlet, 

 and the colder the outside temperature the faster 

 the current of air will circulate through the incu- 

 bator (the greater the volume of air that will pass 

 through in a given time), but the moment the out- 

 side temperature gets as warm as that of the egg 

 chamber the current ceases. Then it follows that 

 more air passes through the egg chamber on a cold 

 day than on a warm one, consequently there is 

 more moisture supplied from the outside on a cool, 

 damp day than on a warm, dry one. 



When you look at all these facts and think ot 

 the difference in incubators, the wonderful variety 

 of climates and altitudes on this vast continent, the 

 different kinds of shells which envelop the eggs 

 thick, hard shell, thin, hard shell, thick porous, 

 and thin porous each requiring different treat- 

 ment (the hard shell requiring more moisture than 

 the porous shell), you will appreciate the difficulty 

 of giving a direct answer to the question of 

 " How much moisture should be used in an incu- 

 bator? " It is impossible, in the ordinary instruc- 

 tions which accompany an incubator, to give 

 directions which will fit every case in every 

 locality, therefore the incubator manufacturer who 

 would conscientiously perform his duty to each of 

 his patrons must have an actual knowledge, 

 which can only be acquired by actual experience, 

 of the action and requirements of his own incubator 

 in the various altitudes and climates of this country 

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