49 



Table XVIII : Actual vs. Apparent Humidity in Nests. 



It was found that several samples could not be taken in succession, 

 for the second and third were invariably lower than the first. Great vari- 

 ations in humidity were found in all nests. For hen No. I. the range was 

 70.6 per cent, to 99.3 per cent.; for No. II., 48 to 83; for 

 No. III., 40.5 to 60.4. Readings were taken in the top of the 

 nest, the bottom, and between the leg and breast, but no uniformity was 

 reached. Of seven readings for hen No. I. the highest was obtained at 

 the bottom, the next three in order were top readings, the remaining three, 

 bottom readings. For hen No. II. the highest was a top reading, the 

 next three were bottom readings, and the remaining one a top reading. 

 For No. III. the highest was between the leg and breast, the second and 

 third bottom readings, the fourth a top reading; the fifth between the leg 

 and breast, and last a bottom reading. Probably much of the variation 

 with these hens might be accounted for if we knew how closely or remotely 

 the reading followed some shifting of the hens. The humidity in nests I. 

 and II. \vas also determined by the "frame" hygrometer, two readings 

 in each case. In No. 1 the absolute method gave a higher reading than 

 the hygrometer; in II. the hygrometer gave the higher reading. Of 

 course the two methods could not be used simultaneously in the same nest, 

 hence in fairness we could compare only the averages. Averaging the 

 two, the hygrometer gave 71.8, the absolute 70.8. Hence we must con- 

 clude that for earth nests at least the nest hygrometer is correct within 

 the limits of experimental error. This is the test previously referred to 

 in discussing the frame hygrometer. Looking now at the vapor pressure 

 in the nests, we see that ftf is from 2\ to 4 times as great as in the room 

 during the same time. 



