160 



THE PEOPLE S PRACTICAL, POULTRY BOOK. 



the same temperature as those above. It is claimed that in this machine 

 that difficulty is entirely overcome ; and that by the arrangement of the 

 ventilators heat is more perfectly under control than has been before at- 

 tained. This an even temperature is the most important point to be 

 secured ; with it success is almost certain ; without it, almost impossible. 

 The proper heat is one hundred and three degrees Fahrenheit ; the minimum 

 being one hundred degrees, and the maximum one hundred and five degrees. 

 It is not always fatal to let the heat go below one hundred degrees, if not 

 allowed to remain so any great length of time ; but a heat of one hundred 

 and seven or one hundred and eight degrees is almost certain death to all 

 unhatched chickens. The period of incubation is not shortened, as many 

 suppose ; or, at most, only one day twenty days being the average time ; 

 and we frequently see hens bring off their broods in that time, if close 

 sitters. The chicks come out remarkably strong and healthy, and are 

 always free from vermin ; and after the first few days require no more care 

 than if hatched under a hen. 



THE GRAVES' INCUBATOR. 



Figure 1 is a perspective view of a portion of an incubator case, showing 

 the ventilating and heat-regulating devices. Figure 2 is a transverse, 

 vertical section of figure 1. Figures 3 and 4 are views in detail of the heat- 



FIG. 1 PERSPECTIVE VIEW OF GRAVES' INCUBATOR. 



regulating devices ; and figure 5 (shown elsewhere,) is a view of an artificial 

 mother, or protector. The object of this invention is to maintain a definite 



