1854 The Cornell Reading-Courses 



in artificial incubation do not admit of so many turnings. However, 

 it has been found essential to turn the eggs twice daily, beginning twenty- 

 four to thirty-six hours after they are put in the incubator and continuing 

 until the nineteenth day of incubation, on and after which the incubator 

 should be kept closed. The additional fact that, as a rule, incubators 

 do not supply an even distribution of heat to all parts of the egg tray, 

 makes it doubly necessary not only that the eggs shall be turned twice 

 each day, but that their positions on the trays shall be changed as regularly 

 as the eggs are turned. Regularity in turning the eggs has mucli to 

 do with the success of the hatch. The best time to turn the eggs in the 

 morning is before any other work has been done in connection with the 

 care of the incubator. The eggs must be turned again in the evening. 

 These times for turning the eggs should be twelve hours apart, as nearly 



as possible. Not only does this ar- 

 rangement enable the operator to have 

 a specified time for doing the work, 

 btit it keeps the times for turning the 

 eggs as far apart as is conveniently 

 possible, and it equalizes the space 

 of time between turnings ^ — two im- 

 portant factors. 



Since the principal reasons for 

 turning eggs are (i) to prevent the 

 iG. 5. urning eggs germ from drydng to the shell and (2) 



to equahze the heat, it is necessary that the eggs be given a thorough 

 shuffling (Fig. 65). This may be done satisfactorily by removing a few 

 eggs from the center of the tray and by rolling the remaining eggs 

 with the palms of the hands. The eggs should be rolled in such a way 

 that those around the outer edges of the tray and in the comers 

 will be worked toward the center, and those from the center toward 

 the outer edges. The eggs taken from the center of the tray at the 

 beginning of the operation should be placed in the comers of the tray. 

 The eggs must not be shoved roughly against one another, nor rolled 

 too vigorously. The tray may be turned end for end at each tuming 

 of the eggs; and if two trays are used they may be interchanged at one 

 tuming and turned end for end the next time. 



Cooling the eggs. — The successful cooling of eggs during incubation 

 counterbalances, to some extent, the still imperfect methods of ventilation. 

 In order to cool eggs properly, the operator must consider the length 

 of time they have been incubated, the weather conditions, and the room 

 temperature. It is not known just how much cooling is necessary for 

 the best results, nor can a time-table be made that will work successfully 



