308 POULTRY BREEDING AND MANAGEMENT 



The purchaser of an incubator is furnished directions for 

 its care, and those directions should be carefully followed 

 until, at least, experience has demonstrated that they may 

 be modified with advantage. Second, the construction of 

 machines varies more or less, and no set of directions will 

 suit all machines. The safe plan, therefore, is to study the 

 directions that come with the machine. While different 

 machines require different methods of operating, on some 

 fundamental points, however, there should be agreement 

 in directions. 



Humidity Conditions. On the question as to whether 

 moisture should be supplied to the incubator, there is a 

 great diversity of views among incubator makers. In ex- 

 periments by the writer at the Utah and Oregon Stations, 

 it has been found that moisture or humidity conditions have 

 a great deal to do in the successful incubation of hen eggs. 



Experiments reported in Utah Bulletin 92 (1905) 

 showed that there was a greater loss in weight of eggs in 

 incubators than under hens during incubation. This loss 

 is largely water evaporated. In the first 18 days of incuba- 

 tion the average loss in incubators was 18.4%, and of eggs 

 under hens the loss was 15%. In later experiments at the 

 same station (Bulletin 102, 1907) machines with no 

 moisture averaged 17.8% loss, medium amount of moisture 

 14%, and with maximum amount of moisture the loss was 

 12.3%. At the Oregon Station, as reported in Bulletin 100 

 (1908) , eggs under sitting hens in dry nests averaged 14.8% 

 loss. In later tests the average was lower than this. The 

 results were for no-moisture machines 16.6% loss, medium 

 moisture 12.8%, and maximum moisture 10.8%. The loss 

 is also affected by the amount of ventilation, as discussed 

 in another place. 



Some startling differences in the hatching were secured. 

 In the Utah experiment (1907) maximum moisture pro- 



