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wilh any nice obferver, that is ftartled at this fuppolition, 
to life his own eyes, and I think he will foon be con- 
vinced. In another clafs of animals, videlicet^ the infe&y 
nothing is fo common as to fee the different fpecies of 
many genera in conjiindion as they fly. The fwift is 
almoll: continually on the wing; and as it never fettles 
on Xhe ground, on trees, or roofs, would feldom find op- 
portunity for amorous rites, was it not enabled to indulge 
them in the air. If any perfon would watch thefe birds 
on a fine morning in May, as they are failing round at a 
great height from the ground, he would fee every now 
and then one drop on the back of another, and both of 
them fink down together for many fathoms, with a loud 
piercing fliriek. This I take to be the jun61;ure when the 
bufinefs of generation is carrying on. As the fwift 
eats, drinks, colle6ls materials for its nefb, and, as it feems, 
propagates on the wing ; it appears to live more in the 
air than any other bird, and to perform all fuiuflions 
there, fave thofe of fleeping and incubation. This hi- 
rundo differs widely from its congeners, in laying inva- 
riably but two eggs at a time, which are milk-white, long, 
and peaked at the fmall end ; whereas the other f^iecies 
lay at each brood from fotir to Jix, It is a mofl alert bird, 
riling very early, and retiring to reft very late, and is on 
the wing, in the height of fummer, at leaft fixteen hours. 
In the longeft days it does not withdraw to reft till a 
quarter before nine in the evening, being the lateft of 
all day-birds. Juft before they retire, whole groups of 
them affemble in the air, and fqueak and fhoot about 
with 
