BLACK SWIFT. 623 



weather was oppressively hot, the atmosphere perfectly stag- 

 nant, and I judged it possible that there might be thunder 

 before night. The Swifts flew at a moderate height, in perfect 

 silence, and appeared busily occupied, neither mingling in 

 groups, nor chasing each other. About six in the evening, 

 having seated myself on a rock on Blackford Hill, I watched 

 about a dozen flying at about the same height over the little 

 valley. They retained the same silence which they had kept 

 all day, flew rather more slowly than usual, and never chased 

 or interfered with each other. The Bank Swallows had re- 

 tired to their holes, a very few Larks and Corn Buntings were 

 heard singing ; but the birds in general were unusually silent. 

 The Swifts now and then came so close to me, that I could 

 perceive with certainty that their mouths were not open, and 

 trace all their motions in a satisfactory manner. They keep 

 the head quite retracted, and rather below the level of the 

 back ; the wings are never fully extended, unless during some 

 sudden turns ; but when the bird is gliding along, the two 

 wings appear to form a curve of about the third of a circle ; 

 the tail is very slightly spread so that the fork is just percepti- 

 ble, but, during deflection in a vertical direction is spread out 

 and depressed or elevated. On returning home, I found the 

 Swifts flying low over the houses, much in the same style, but 

 occasionally emitting a scream, which had not however the 

 usual joyous expression. The dark haze hung over the sky, 

 but, although the air bad an electric feeling, and there was not 

 a breath of air, no thunder was heard, and no rain fell. The 

 weather continued the same until eight next morning, when 

 a slight breeze sprung up, a smart shower of very heavy drops 

 fell, and by ten the sky was clear, with thin cirrocumuli, and 

 a light wind. In the evening the Swifts flew more joyously, 

 screaming and chasing each other. The heat was then much 

 less oppressive, for there was a good breeze, and a clear sky. 



On the fourth day, the weather was close and sultry. The 

 Swifts were silent. At five rain fell, and continued until night. 

 For an hour or so, no Swifts were seen, but in the evening 

 they were flying just over the houses, in the midst of the rain, 

 dashing along, and screaming, in their most joyous mood. 



