42 



These tests established beyond doubt that our second objection was 

 well founded, that the "egg" did bottle up the moisture and thus give 

 readings far too high. If all the differences of both tests are averaged we 

 find the egg readings too great by 15.7. Referring to Table XII., and 

 subtracting 15.7 from the "egg" humidities, we obtain the next column, 

 the humidities by the "frame." 



But doubtless in the minds of some there is an objection to even the 

 "frame" hygrometer: The wet bulb is giving vapor to the air in the 

 nest, and although it cannot eive enough to saturate the air, still it may 

 be giving sufficient to raise the humidity considerably above what it would 

 be if the wet bulb were not there. This objection seems plausible, but it 

 may be stated here that during the present season (1907) the "frame" 

 hygrometer in the nest was subjected to a rigorous test by the absolute 

 method and it was established that the hygrometer readings are not in 

 error to any appreciable extent. Details of this test will be given later 

 in another connection. Then taking as correct the humidity of the nests 

 as given by the frame hygrometer, we observe that it is very much higher 

 than the fanned reading in the dry machines, as 59 is to 39. (See Tables 

 IX. and XII.) Hence if we are to take the hen as our guide we must infer 

 that dry incubators have not sufficient moisture, and that incubators 

 cannot be expected to give best results unless they are made as moist as 

 the hen's nest. 



Now referring to Table XII., and comparing the various kinds 

 of nests, we observe that the rubber and the earth nests had highest 

 humidity, and that they also hatched best. Barring the board nests, where 

 5 eggs were broken, the hatch increased or decreased as the humidity did. 

 Referring to Table No. IX., it will be seen also that on the average 

 the "wet" machines, or machines into which moisture was introduced, 

 gave a considerably greater hatch than did the dry ones, in the case of 

 both the selected and the shuffled eggs, though the difference was the 

 more marked on the latter. Hence from the practical side also for both 

 the hens and the incubators we thought it a fair conclusion from the work 

 of 1906 that high humidity must be productive of larger hatches. This 

 conclusion has been thoroughly confirmed by the extended tests of 1907. 

 Consulting Table No. VII., the reader will observe that 1,221 eggs 

 were set in machines where moisture was introduced by use of water only, 

 and 1,406 in dry machines. In the "wet" machines the hatch was 51.9 per 

 cent, of the total eggs set; in the '.'dry" machines it was only 40.7 per 

 cent. Then besides, more chicks hatched in "wet" machines lived than 

 those hatched in dry ones, 63 per cent, of the former living to the age of 

 four weeks as against 39.5 per cent, of the latter, or, counting the chicks 

 alive at the end of four weeks in terms of total eggs set, the "wet" 

 machines produced 32.7 per cent, as many chicks as eggs set and the dry 

 machines 16. 1 per cent., or less than half as many as the wet. 

 Or stating it otherwise, 3 eggs in a wet machine produce 1 chick four 

 weeks of age, while it takes 6 eggs in a dry machine to produce 1 chick 



