258 POULTRY CULTURE 



the lot. Eggs with irregular and defective shells are often hatched 

 artificially, when by the natural method they would be likely to 

 be broken. Even a cracked egg may be patched with sticking 

 plaster, or with a piece of paper gummed over the crack, and 

 successfully incubated. The use of ill-formed and defective eggs 

 is not advised except in case of scarcity of perfect eggs, when it 

 may be better to fill up the incubator with such eggs as are. avail- 

 able than to wait until the required number of selected eggs can 

 be obtained. The eggs used should be as fresh as possible. It is 

 desirable that they be from vigorous stock that is known to be pro- 

 ducing strongly fertile eggs, but as a rule the quality of the eggs 

 secured for first hatches is doubtful to be determined only by 

 the result. 



Preliminary regulation of heat. A new incubator, or one that 

 has been out of use for some time, should be run empty for several 

 days, no eggs being put into it until it is adjusted to and running 

 steadily at 103. It will require several hours to bring the egg 

 chamber back to that temperature after cold eggs are placed in it. 

 Then the actual process of incubation begins. 



Routine work of incubator operation. The ordinary routine of 

 incubator operation is as follows : The lamp is filled once a day, and 

 the wick trimmed at that time and also, if it seems necessary, after 

 twelve hours. If the lamp is small, or if oil of inferior. quality is used, 

 it is better to remove the charred scale from the wick twice a day. 



Turning the eggs is begun on the third day and continued twice 

 daily until the eighteenth day (for ducks' eggs, the twenty-fourth 

 day), after which the eggs should not be turned. For a long time 

 it was the common practice to turn the eggs by placing an inverted 

 tray over the tray containing the eggs, and, holding the two trays 

 tightly together, turning them so as to place the eggs, turned half 

 over, in the new tray. The method now generally preferred is by 

 shuffling, which only slightly changes the position of the egg and 

 more closely conforms to the conditions in natural incubation. 

 Some machines have attachments for turning the eggs without 

 removing from the machine, but operators generally prefer to take 

 them out. 



Cooling the eggs begins simultaneously with turning. Until the 

 seventh day the cooling incident to the removal of the eggs for 



