Importance of Air in the Incubator. 65 



Mr. Halsted's minute directions to somewhat raise it at this period, we need hardly say this lot 

 altogether failed ; none of the chicks having properly absorbed the yolk for want of sufficient 

 heat. Of the third four eggs, one hatched, and this is the last trial the result of which has 

 reached us. We add a few of Mr. Wren's own notes, as they are both interesting, and may be 

 practically useful to other experimenters in the same direction. 



"My conclusion is that the heat should not be more than 102" for the first ten days; after 

 that should not fall on any account below it, but be rather higher, and ^ith. plenty of air. In this 

 I feel sure we are imitating Nature ; because a hen when she first commences to sit has feathers 

 between her body and the eggs, which are non-conductors of heat. By the friction of the eggs 

 these wear off, and her body comes in direct contact with the eggs ; therefore the heat must, if 

 any dift'crence, be rather greater the latter part of the time. The four eggs that hatched so well 

 were in the incubator from the first, and were kept at from 102'' to 104°, with plenty of fresh air 

 several times a day. Instead of damping, a small vessel of water was placed in one corner of the 

 egg-drawer. 



" I may add that it is very easy to be deceived as to uniformity of temperature. In my 

 first experiments I laboured under an impression that the temperature had not varied one degrep, 

 because in the morning I found the heat the same I had left it at night ; but when I put in a 

 ' registering thermometer, I found it had varied six degrees during the night. 



" While I think that the first ten days under the hen is the most critical period as to the 

 danger of a chill, I do not consider it so in the incubator, only so far as requiring a more uniform 

 temperature and not alloiouig it to exceed 102". I have found that at that stage 106° continued for 

 a few hours will destroy the vitality altogether.* 



"I think I have learnt more by my failures than by my first success. The reason of the 

 latter I believe to be, that during the incubation of the first eggs I was continually making 

 alterations, and sometimes the drawers were out and the incubator stopped for half an hour several 

 times a day ; consequently they got more air than those put in since. I have also examined the 

 eggs under a sitting hen, and mad'- the following memoranda of the position of the eggs during a ' 

 part of one day : — ■ 



" At 10.30 a.m. marked four eggs, and left them in the centre of the nest. 



"At 1.30 p.m. three of the marked eggs were moved to the outside ; one still left near the 



centre. Marked three more, and left them in the middle. 

 "At 2.4s p.m. the three marked last were moved to the outside, also the four marked first 



were still on the outside. Marked four more, and left them in the middle. 

 " At 4 p.m. the four marked last were on the outside, and some of those marked first were 

 back again to the middle of the nest. 

 " This I think proves that a hen is continually moving her eggs to the outside, so that they 

 obtain fresh air ; and my future experiments will be directed to supply the eggs in the drawer with 

 a certain amount of air continually." 



Mr. Wren adds that the first four eggs which hatched so successfully were Brahmas, while 

 the others were Hamburghs ; and as under the hens at the same period he found his Brahmas 



* This paragraph was written in reply to a communication from ourselvss embodyinj Mr. Halsted's experience as to the impor- 

 tance of the first ten days. The words italicised are remarkable ; since, while the writer supposes he disagrees with Mr. Halsted, 

 in reality his own obseiTations exactly corroborate him. 



9 



