NATURAL HTSTOUY OF SELBOENE. 
131 
As I have regarded these amusive birds with no small attention, if I 
should advance something new and peculiar with respect to them, and 
different from all other birds, I might perhaps be credited ; especially 
as my assertion is the result of many years exact observation. The 
fact that I would advance is, that swifts tread, or copulate, on the 
wilig ; and I would wish any nice observer, that is startled at this 
supposition, to use his own eyes, and I think he will soon be convinced. 
In another class of animals, viz. the insect, nothing is so common as to 
see the different species of many genera in conjunction as they fly. The 
swift is almost continually on the wing ; and as it never settles on the 
ground, on trees, or roofs, would seldom find opportunity for amorous 
rites, was it not enabled to indulge them in the air. If any person would 
watch these birds of a fine morning in May, as they are sailing round 
at a great height from the ground, he would see, every now and then, 
one drop on the back of another, and both of them sink down together 
for many fathoms with a loud piercing shriek. This I take to be the 
juncture when the business of generation is carrying on. 
As the swift eats, drinks, collects materials for its nest, and, as it 
seems, propagates on the wing, it appears to live more in the air than 
any other bird, and to perform all functions there save those of sleeping 
and incubation. 
This hirundo differs widely from its congeners in laying invariably 
but two eggs at a time, which are milk-white, long, and peaked at the 
small end ; whereas the other species lay at each brood from four to six. 
It is a most alert bird, rising very early, and retiring to roost very late ; 
and is on the wing in the height of summer at least sixteen hours. In 
the longest days it does not withdraw to rest till a quarter before nine 
in the evening, being the latest of all day-birds. Just before they retire 
whole groups of them assemble high in the air, and squeak, and shoot 
about with wonderful rapidity. But this bird is never so much alive as 
in sultry thundry weather, when it expresses great alacrity, and calls 
forth all its powers. In hot mornings several, getting together in 
little parties, dash round the steeples and churches, squeaking as 
they go in a very clamorous manner ; these, by nice observers, are 
supposed to be males serenading their sitting hens ; and not without 
reason, since they seldom squeak till they come close to the walls or 
eaves, and since those within utter at the same time a little inward note 
of complacency. 
When the hen has sat hard all day, she rushes forth jjist as it is 
almost dark, and stretches and relieves her weary limbs, and snatches 
a scanty meal for a few minutes, and then returns to her duty of 
incubation. Swifts, when wantonly and cruelly shot while they have 
young, discover a little lump of insects in their mouths, which they 
pouch and hold under their tongue. In general they feed in a much 
higher district than the other species ; a proof that gnats and other 
insects do also abound to a considerable height in the air ; they also 
range to vast distances, since locomotion is no labour to them who are 
endowed with such wonderful powers of wing. Their powers seem to 
. be in proportion to their levers ; and their wings are longer in pro- 
portion than those of almost any other bird. When they mute, or case 
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