262 



POULTRY CULTURE 



chamber, so the condition of the egg chamber is affected by the 

 condition of the apartment in which the incubator is operated. 

 Thus the problem of ventilatio;i becomes a matter of the proper 

 adjustment of the machine to its atmospheric environment, to secure 

 the normal evaporation of the eggs. If the atmosphere of the apart- 

 ment is relatively dry, a ventilator of fixed opening may remove 

 moisture from the egg chamber too fast, and the air in it will be- 

 come so dry that the rate of evaporation from the eggs will be 

 too high. Then evaporation could be checked by moistening the 

 air (wetting the floor) of the room, by placing moisture pans in 



the egg chamber, or by 

 reducing the ventila- 

 tor opening. Deficient 

 evaporation would be 

 remedied, in an incu- 

 bator with supplied 

 moisture, by removing 

 water from the egg 

 chamber, by increasing 

 the ventilator open- 

 ing, or by increasing 

 the ventilation and 

 reducing the humidity of the air in the room ; in a nonmoisture 

 machine the deficiency would be remedied by the two means last 

 mentioned. 



Measuring ventilation. The standard gauge of ventilation is 

 the rate of evaporation in natural incubation. Comparison may be 

 made either on a basis of the size of the air cell as observed by 

 testing, or by weighing eggs artificially incubated from time to time 

 and comparing the loss of weight with the standards experimen- 

 tally determined from natural incubation. With suitable scales each 

 tray used may be weighed empty and the weight marked on it, 

 weighed with the eggs when filled, and afterwards as often as de- 

 sired. The data as given for one five-day and two seven-day periods 

 are not adapted to this purpose. As it is desirable to discontinue the 

 handling of eggs after the eighteenth day, the best arrangement is 

 to make the weighings at the close of the sixth, twelfth, and eight- 

 eenth days. For six-day periods the loss of weight is approximately 



Fig. 297. 



Egg just before exclusion and partially 

 excluded chick 



