44 



Floor Watered. 



The first reading- shows that when the humidity was low the difference 

 was high, 23.3 as compared with 15.7 in the hens' nests. The second 

 reading shows that with higher humidity the difference was less, being 

 only 12.7. Many readings not recorded here were taken from time to 

 time at average humidities of from 50 to 65, and the difference was always 

 in the neighborhood of 15 per cent., very close to the difference in the 

 nest. Was it possible that the air-movement in the hen's nest was equiva- 

 lent to free diffusion in the room? It did not seem credible. The tem- 

 peratures of course are not the same in the two cases, so that the tests 

 are not exactly parallel, still the existence of the same difference between 

 the hygrometers in the nest, as in the room, pointed strongly to the sus- 

 picion that the nest was subject to air movement equal in effect to the 

 free diffusion of the room. If so, then the reading of the "frame" hygro- 

 meter was really a fanned reading, and, therefore, strictly accurate; of 

 which more later. 



But how can we reconcile the ideas of rapid air movement and high 

 nest humidity? Surely there is not enough evaporation from the eggs 

 to maintain such high humidity in the face of such rapid circulation. Let 

 us examine. Referring to Table XII., under "evaporation" we learn 

 that the average loss from all eggs under hens in 1906 was 12 per cent, 

 of their original weight. The ventilated and board nests, however, are 

 unnatural conditions, and the evaporation is high, hence in any argument 

 based on evaporation these nests should be omitted. The average evap- 

 oration in the remaining kinds of nests is 11 per cent. The weight of a 

 setting of eggs is about 26 ounces, and the evaporation would thus be 

 2.86 ounces. And this divided up equally amongst the first 19 days is 

 sufficient to saturate the air under the hen at least four times an hour for 

 the whole period. This known, it is not so difficult to conceive of high 

 humidity in the face of rapid air movement. Moreover, it is possible that 

 some moisture comes from the hen's body, aiding in the maintenance of 

 the high humidity. 



Circulation in Incubators. 



The idea of circulation in the nests led us to the consideration of cir- 

 culation in incubators, but owing to the incompleteness of the work on 

 the former the latter has been held in abeyance. It may be stated, how- 

 ever, that the differential reading between the "egg" and the "frame" 



