1865.] Dr. Davy on the Temperature, $c. } of Birds. 



445 



December 2nd. 10 45 A.M., air 58 

 11 45 58 



12 45 P.M., air 58 



Owl .... 100 



93-25 



86-25 



.... 80-50 



.... 75'75 



.... 72 



.... 69-25 



.... 64-50 



61-25 



.... 59-25 



.... 54-5* 



.... 56-25 



.... 57 



,, .... 58-5 



57 



55-5f 



.... 58-5 



57 



These results seem sufficient to show that birds owe much of their high 

 temperature, especially its preservation, to their clothing of feathers. 

 Further, it may be remarked in proof of the little activity of their cuticular 

 structure (except, indeed, in the growth of feathers), that birds are never 

 observed to eat, or have their feathers wet from condensation on them 

 of perspired moisture ; nor am I aware that their breath becomes visible, 

 to use a popular expression, in the coldest weather. And in accordance 

 it would appear, comparing birds with animals of other classes, that the 

 proportion of their aqueous element is somewhat less, which also harmo- 

 nizes with an inconsiderable cooling effect from cutaneous evaporation a 

 fact which some of the results given seem to prove, and as is shown by the 

 following, so far as trials on the dead are applicable, inferentially to the 

 living animal. 



Of four sparrows just shot, one (No. 1) weighing 414*5 grs. was sus- 

 pended with its feathers entire ; a second (No. 2) clipped, i. e. its feathers 

 cut short, weighing 405-6 grs. (it had lost 23 grs. by the clipping), was 

 suspended by its side, as were also the other two ; No. 3, deprived of its 

 feathers, its skin unbroken, weighing 414 grs. ; No. 4, deprived of its 

 skin as well as its feathers, weighing 384-5 grs. During twenty-four 

 hours' exposure to the air of room varying from 48 to 50, No. 1 lost 1-5 

 per cent.; No. 2, 2-3 ; No. 3, 7'9 j No. 4, 17'4. 



* In the room there was no fire from 5 P.M. on the 2nd to 8 A.M. on the 3rd ; during 

 the night the thermometer in air must have been below 54 -5 ; in a small cup of water 

 close to the bird at 9 A.M. it was 53. 



t Water in cup covered 55. 



