182 
THE NATURAL HISTORY 
[LETT. 
and wonderful, since that time is often the sweetest season in 
the year. But, what is more extraordinary, they begin to retire 
still earlier in the most southerly parts of Andalusia, where they 
can be no ways influenced by any defect of heat : or, as one 
might suppose, defect of food. Are they regulated in their 
motions with us by a failure of food, or by a propensity to 
moulting, or by a disposition to rest after so rapid a life, or by 
what ? This is one of those incidents in natural history that 
not only baftles our searches, but almost eludes our guesses ! 
These liirunclines never perch on trees or roofs, and so never 
congregate with their congeners. They are fearless while haunt- 
ing their nesting-places, and are not to be scared by a gun ; and 
are often beaten down with poles and cudgels as they stoop to 
go under the eaves. Swifts are much infested with those pests 
to the genus called hippoboscm {Anaperm hiriindinis, Leach), and 
often wriggle and scratch themselves, in their flight, to get rid of 
that clinging annoyance. 
Swifts are no songsters, and have only one harsh screaming 
note ; yet there are ears to which it is not displeasing, from an 
agreeable association of ideas, since that note never occurs 
but in the most lovely summer weather. 
They never settle on the ground but through accident ; and 
when down can hardly rise, on account of the shortness of their 
legs and the length of their wings : neither can they walk, but 
only crawl ; but they have a strong grasp with their feet, by 
which they cling to walls. Their bodies being flat, they can 
enter a very narrow crevice ; and when they cannot pass on their 
bellies they will turn up edgewise. 
The particular formation of the foot discriminates the swift 
from all the British hvmndines; and indeed from all other known 
birds, the Hirnndo melba, or great white-bellied swift of Gibral- 
tar, excepted ; for it is so disposed as to carry " omnes quatuor 
digitos anticos " — "all its four toes forward;" besides, the least 
toe, which should be the back one, consists of one bone only, and 
the other three of only two apiece : a construction most rare 
and peculiar, but nicely adapted to the purposes in which their 
feet are employed. This, and some peculiarities attending 
the nostrils and under mandible, have induced a discerning 
