BRITISH BIRDS OF FASTEST FLIGHT 41 
lengthened, and tapering backwards. The diffi- 
culty in regard to these birds, and particularly in 
regard to the Alpine swift and the spine-tailed 
swift, is to obtain the necessary opportunities and 
conditions for comparing their maximum speed 
with that of other very fast birds. It is difficult 
to realise merely from a consideration of the 
description and measurements of these three 
swifts in the authoritative works of ornithologists 
how much larger the Alpine swift and spine- 
tailed swift are than the common swift. I have 
had opportunities of handling and examining the 
stuffed specimens of these birds in the British 
Museum (Natural History) at South Kensington, 
and should like to acknowledge here the courtesy 
and assistance given to me at the Museum by 
Mr. W. P. Pycraft, Dr. P. R. Lowe, and 
Mr. N. B. Kinnear. 
The actual measurements of the three birds are 
as follows : 
Length. Wing. 
Common Swift . . . 6-75 inches 6-8 inches 
Alpine Swift .... 8 „ 8-45 „ 
Needle-tailed S\\'ift ... 8 „ 8-1 „ 
It is not generally realised that the common 
swift, so well known in this country, which looks 
so imposing in flight as it glides overhead with 
6 
