INCUBATION 257 



light conditions continue in the i?itervals betzveen the regular 

 hours for attending the incubator. This will depend mostly upon 

 the faithfulness and skill with which instructions have been fol- 

 lowed, and upon the judgment used in modifying them to suit local 

 conditions, but occasionally also upon weather changes. Thus, after 

 filling lamps and trimming wicks, many operators return in the 

 course of fifteen or twenty minutes to see that lamps are burning 

 well. They also take a look at the incubators, noting the temper- 

 ature and the condition of the flame whenever they happen to be 



Fig. 287. Interior of incubator cellar at Pittsfield Poultry Farm, Pittsfield, Maine, 



showing one side of a mammoth (Hall) incubator of six-thousand-egg capacity 



(Photograph from Pittsfield Farm) 



near them. In extreme cold weather or in high winds they watch 

 the incubators very closely, for it is under such conditions that the 

 ordinarily automatic regulator is most likely to become erratic. 



Selection of eggs for artificial incubation. Considering only the 

 matter of incubation, selection of eggs need not be as rigid for 

 artificial as for natural incubation. When the eggs are to be turned 

 in the trays they must be of uniform size or many may be broken 

 in turning. When eggs are turned by hand, by shuffling on the 

 tray, uniform size is not so essential, although as a rule it is not 

 desirable to use those varying much from the average size of 



