8o 



THE BOOK OF FOULTRY. 



customary to keep the best thermometers for six 

 montlis in a heated chamber before supplying 

 to the incubator manufacturers, and it is desir- 

 able that this system should be followed. Any 

 thermometer can be easily used, by ascertaining 

 its " correction " from the standard one, which is 

 best done by immersing both in a pail of water 

 heated to about 105°, and kept stirred : without 

 stirring, the water may heat the two quite differ- 

 ently. The test described by some of putting 

 the thermometer into the mouth is not to be 

 depended upon within two degrees. 



For these thermometric reasons, first adjust- 

 ments of temperature may fail in practice ; but 

 there is a simple common-sense rule by which 

 in that case the error may be corrected. If fresh 



of 106^ would either kill chicks outright, or so 

 weaken them that they would probably die in 

 the shell ; whereas later on an accidental baking 

 will, if in a dry chamber, often be borne with 

 impunity — even 112° for four hours has then 

 been recorded, with still a fair hatch. It 

 has been found that if such a state of affairs 

 occurs, the best procedure is quickly to damp 

 a towel with warm water and spread it on 

 the eggs, replacing the tray, but leaving the 

 door open for a while. This cannot be done 

 unless there is a door independent of the 

 drawer or tray ; otherwise, leave the drawer 

 partially open for a while. Such a door, in- 

 cluding a glass door, is very desirable for all 

 sorts of reasons, and especially for reading the 



hen's eggs which hatch pip between the evenings 

 of the twentieth and twenty-first days the heat 

 has been about right ; at all events the average 

 heat, apart from faults in regulation.* If the 

 eggs pip a day earlier the heat has been too 

 great, and a shade lower had better be tried. 

 If on the contrary fresh eggs are decidedly late, 

 then the regulator should be set a little higher, 

 whatever the thermometer may appear to read. 

 It is especially to be remembered, that too high 

 a temperature is particularly fatal during the 

 -first ten days. During that period a few hours 



• Bantams' eggs, and other small ones, average a clay or more 

 earlier, and should reckon accordingly. 



thermometer. Where there is none, the stem 

 must either be pulled out or the drawer opened. 

 In the latter case the reading must be taken 

 instantly, as there will be a rapid fall. In some 

 of the large establishments of America a small 

 electric light is fitted up close to each thermo- 

 meter, which is switched on and the reading taken 

 as the attendant passes each machine in turn. 



The temperature should have been held 

 steady for at least a day before any eggs are 



introduced. Of course, it is foolish 

 Eg&s°^ °^ *° "^"^ valuable eggs in a first 



essay ; fresh and strongly fertile 

 common eggs should comprise the first attempt 



