74 THE PRACTICAL POULTRY KEEPER. 



that of moisture. One circular before us claims that the 

 special machine described "evaporates treble the amount of 

 moisture of any other machine, hence its great success." It 

 is simply a disastrous mistake. As a rule we believe it to be 

 true that hot-air incubators, especially such as admit lamp- 

 products direct, need more moisture than tank machines, 

 owing to the greater dryness of their atmosphere. But 

 having investigated this matter very carefully, some results 

 are simply baffling to all theory we have been able to frame, 

 and make mincemeat of explanations published by some 

 pretentious treatises which purport to declare the " laws " of 

 the process. To take one of the most startling, which 

 reaches us from America, where the summers are far hotter 

 and dryer than here : Captain Casey reported (from the 

 celebrated Aratoma Farm, Katonah, New York) on hatches 

 with a leading American incubator, known as the Prairie 

 State machine. The incubator is a hot-air one ; the locality 

 is on high table-land ; the incubator-house (differing from 

 the usual American practice) is two feet above the ground ; 

 the time was the hot and dry August of 1896 ; the windows 

 of house open on all sides. No moisture whatever was used, 

 and yet out of 227 fertile eggs 212 strong chickens were 

 hatched ; and we have other very similar instances. 



We are, however, convinced that eggs do as a rule need 

 more moisture in incubators, the eggs not being gradually 

 greased as by the body of a hen, which checks evaporation. 

 We have reason to believe that wiping with a very slightly 

 greased cloth when turning, might prove a promising line 

 of experiment bearing on that point. But we also believe 

 that more chickens are lost by too much moisture than from 

 any other cause ; that little is needed the first week, and 

 that after that it should be graduated according to weather, 

 giving more in brisk dry weather than in close. Excess 

 acts by packing the egg too full to hatch. The air-cell 



