174 NATURAL HISTORY 



may-flies, and dragon-flies) that were just emerged out of 

 their aurelia state. I then no longer wondered that they 

 should be so willing to stoop for a prey that afforded them 

 such plentiful and succulent nourishment. 



They bring out their young about the middle or latter end 

 of July : but as these never become perchers, nor, that ever 

 I could discern, are fed on the wing by their dams, the 

 coming forth of the young is not so notorious as in the other 

 species. 



On the thirtieth of last June I untiled the eaves of an house 

 where many pairs build, and found in each nest only two 

 squab naked pulli : on the eighth of July I repeated the same 

 inquiry, and found they had made very little progress towards 

 a fledged state, but were still naked and helpless. From 

 whence we may conclude that birds whose way of life keeps 

 them perpetually on the wing would not be able to quit their 

 nest till the end of the month. Swallows and martins, that 

 have numerous families, are continually feeding them every 

 two or three minutes ; while swifts, that have but two young 

 to maintain, are much at their leisure, and do not attend on 

 their nests for hours together. 



Sometimes they pursue and strike at hawks that come in 

 their way ; but not with that vehemence and fury that swal- 

 lows express on the same occasion. They are out all day long 

 in wet days, feeding about, and disregarding still rain : from 

 whence two things may be gathered ; first, that many insects 

 abide high in the air, even in rain ; and next, that the feathers 

 of these birds must be well preened to resist so much wet. 

 Windy, and particularly windy weather with heavy showers, 

 they dislike ; and on such days withdraw, and are scarce ever 

 seen. 



There is a circumstance respecting the colour of swifts, 

 which seems not to* be unworthy our attention. When they 

 arrive in the spring they are all over of a glossy, dark soot- 

 colour, except their chins, which are white ; but, by being all 

 day long in the sun and air, they become quite weather- 

 beaten and bleached before they depart, and yet they return 

 glossy again in the spring. Now, if they pursue the sun into 



