1 78 PO UL TR T- CRAFT. 



pure, then ascertain by experiment the amount of moisture needed to maintain 

 proper evaporation. The simplest method of determining the exact quantity 

 of moisture necessary is by testing the eggs. According to Boyer : 



-, ^*^~ ^^^ " The air cell on the fifth day should measure about 



a quarter of an inch ; on the tenth day, a half an inch ; 

 on the fifteenth day, about five-eighths of an inch; 

 and about three-quarters of an inch on the nineteenth 

 day, the measurement taken in the middle of the 

 egg. Such air cells indicate the proper amount of 

 moisture; if less than that, too much moisture is 

 given ; if more, there is a lack of moisture." 



257. Turning the Eggs. 



"The eggs should be turned twice a day up to the nine- 

 teenth day.* If this is not done, many of the germs will 

 dry fast to the shell during the early stages, owing to the 

 influence of a high temperature and the breaking up of 

 the arrangement of the albumen, which then allows 

 the germ to be pressed upward with some force. * * * 

 Fig. 79. DiagraTshowing Correct Pro- When the egg is not turned during the later stages of 

 portions of Air Space at Different Stages of incubation, the embryo does not attain a natural 

 Incubation. position, and has little chance of being excluded. 



(By courtesy of Prairie State Incu. Co.) Wheil turning the eggs during cold weather it should 

 be done as quickly as possible, so that eggs and chamber lose but little warmth. The 

 position of the trays should be shifted at least once a day, so as to equalize the heat, as 

 in no large machine can the eggs be heated sufficiently near a uniform temperature to 

 warrant leaving them in the same relative position throughout the hatch." (Cyphers). 



258. Cooling, or Airing, the Eggs. Some of the highest authorities 

 disagree on this point. The disagreement when analyzed, seems to be more a 

 matter of form than of fact. Cyphers maintains that cooling is unnecessary, 

 and seems to leave the reader to infer that it is objectionable. Campbell and 

 McFetridge, while admitting that good hatches may be made without cooling 

 the eggs, assert that better, more vigorous chicks are hatched when the eggs 

 are properly aired. Campbell's rule for airing is: "None at all in cold 

 weather; a great deal in hot weather, with variations to suit between." The 

 directions for cooling given by McFetridge are : 



WITH A HOT WATER MACHINE. Commence to cool on the fourth day. Keep them 

 out for a few minutes only at first. Always close the doors of a hot water machine, and 

 cool the eggs outside. (If the doors of a hot water machine are left open, the water in 

 the tank, which is the source of heat, is cooled). Do this every morning. Toward the 

 last part of the hatch, about the seventeenth day, let them cool twenty minutes with 

 the temperature of the room about 60 degrees.t 



* NOTE. Some operators do not begin turning until after the fourth day, but all authorities are agreed as to the 

 necessity of turning from that time up to the nineteenth day, and that after the nineteenth day they should not be 

 turned. 



t NOTE. As to the rate at which eggs will cool, Cyphers says: "Under the influence of an atmospheric 



