INCUBATION 265 



fault in incubation would have made a good hatch impossible, no 

 matter how good the eggs. If it is known that eggs from a certain 

 lot are hatching 80 per cent, either under hens or in other incu- 

 bators, a much lower hatch in any case is reasonably conclusive 

 evidence that the hatch was not properly handled. In such a case 

 the experienced operator knows that something went wrong during 

 incubation, though he may not know what it was ; 1 the inexpe- 

 rienced operator is likely to blame the machine. In a sense it 

 may be the fault of the machine, but the operator is responsible 

 for the machine. It is his business to know its limitations and to 

 see that everything essential to successful incubation is done. 



Common errors in operating incubators. The most prevalent 

 faults in the management of incubators are (i) irregular and defi- 

 cient attention and (2) poor judgment in ventilation and moisture. 

 Errors of the first class are easily corrected if the operator can look 

 after the work at frequent intervals, and if he gives his attention 

 to it. Errors of the second class are more difficult to overcome. 

 They can be definitely ascertained only when other causes of poor 

 hatches have been eliminated. They are affected by variations in 

 general atmospheric conditions, by the volume of air and the venti- 

 lation in the apartment in which the incubators are placed, and by 

 the number of incubators in the apartment. The best adjustments 

 are soonest found when several incubators of the same make are 

 operated at the same time on eggs of the same kind, and slight 

 variations in ventilation and moisture are made in the different 

 machines. 



1 The most remarkable case of this kind that I have known was reported to me 

 by one of the most successful growers of winter chickens. From two incubators of 

 36o-egg capacity, set with eggs from the same lot, he took, on the same day, from 

 one machine 299 chicks, from the other a few over 300 (the exact number I do 

 not now recall). Three months later he still had the 299 chicks from the first in- 

 cubator, but not a single chick of the second lot remained alive. They had died 

 at first by the score, then in smaller numbers until all were gone. As far as the 

 operator knew, the incubator was run correctly throughout the hatch, but from the 

 results (the chicks being brooded under exactly the same conditions) he knew 

 that something went wrong. 



