A Book on Birds 



atmosphere; and so must they to get them. 

 While a heavy, moist air pulls both down 

 close to the surface of the earth. And who 

 has not seen this? The birds soaring at 

 times in a bright, blue sky so far aloft 

 they were almost invisible; and, again, on 

 a changeful day sweeping by so low as to 

 just graze the tops of the fences. 



The Chimney Swift is very softly and 

 closely feathered, and in color is an ashen- 

 black above, and a pearl-gray upon throat 

 and upper breast. 



What becomes of him in winter has 

 been a much-mooted question among orni- 

 thologists, some of whom, after repeated 

 unsuccessful efforts to find the terminus 

 of his annual migration southward, declare 

 that he seems to literally disappear from 

 the face of the earth during the entire time 

 cold weather prevails. Whether this means 

 that he hibernates somewhat after the habit 

 of snakes and bats; or, as is more likely, 

 seeks some congenial bourne thus far 

 unknown to us, is a matter still to be 

 exactly determined. 



[66] 



