178 POULTRY-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: 
5 ‘“‘ 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; 
a0 and about three-quarters of an inch on the nineteenth 
day,— the measurement taken in the middle of the 
15 egg. Such air cells indicate the proper amount of 
moisture; if less than that, too much moisture is 
49 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 tothe 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. Diagram Showing 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.) When 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: 
Witu A Hort 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 unti! 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 atmospherie 
