156 The Natural History 



nidification quite in the dark, in crannies of castles, and 

 towers, and steeples, and upon the tops of the walls of 

 churches under the roof; and therefore cannot be so 

 narrowly watched as those species that build more 

 openly : but, from what I could ever observe, they begin 

 nesting about the middle of May ; and I have remarked, 

 from eggs taken, that they have sat hard by the ninth of 

 June. In general they haunt tall buildings, churches, 

 and steeples, and breed only in such : yet in this village 

 some pairs frequent the lowest and meanest cottages, and 

 educate their young under those thatched roofs. We 

 remember but one instance where they breed out of 

 buildings ; and that is in the sides of a deep chalk-pit 

 near the town of Odiiiam, in this county, where we have 

 seen many pairs entering the crevices, and skimming and 

 squeaking round the precipices. 



As I have regarded these amusive birds with no small 

 attention, if I should advance something new and pecu- 

 liar 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 wing : 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 amor- 

 ous 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 tiiey 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 



