NATURAL HISTORY OF SELBORNE. 175 



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, 

 thundery 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 serenad- 

 ing 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 jusb 

 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 



