June 1, 1897.J 



KNOWLEDGE 



145 



On June 8rd she -will again be at greatest brilliancy, so 

 that she will be favourably situated for day views most of 

 June. 



Being now a little south of the sun, we know that if we 

 mark a place from which the sun will be just hidden by a 

 chimney or gable at noon, Venus will be a certain distance 

 below that point at a certain time before the sun ; or we 

 may mark a place from which the sun appears the right 

 distance above the object we have ch(S3u, and Venus will 

 be just over it. 



This table will show how much to allow for different 

 dates : — 



Venus South of Sud. Venus Souths, 

 h. m. 



June 4th ... ll°i ... 9 18 



,, nth ... ll°i ... 9 7 



„ 18th ... 10°i ... 8 59 



„ 2.5th ... 9°' ... 8 64 



If we fail to find her by this method, we can get up 

 before the sun and keep her in sight all day, by con- 

 tinually making fresh marks. 



When we have once seen her we can make a mark from 

 which she will appear exactly above the chimney, and we 

 shall have no difficulty in seeing her again. 



If such a method be adopted we can easily find her 

 without any optical aid ; indeed, I have found her when out 

 in a field where I scarcely knew my bearings, on a hazy 

 day, without any protection from the light of the sun. 



As it is always an advantage to be shaded from the sun, 

 the south-west side of a house is a good place from which to 

 observe. We may also observe from the open window of 

 a room, keeping as far back into the room as the altitude 

 of Venus will allow, as this shields us not only from the 

 light of the sun, but the brightness of the sky, which 

 would otherwise be glaring us. 



For the same reason Venus is seen very distinctly when 

 the sun is obscured by a large cloud. 



If, in addition to the sun's being hidden by a cloud, the 

 sky be of that brilliant clearness generally prevalent in 

 windy, showery weather, then sometimes — even if it be 

 mid-day — Venus will be seen almost to sparkle, and it is 

 impossible to glance in her direction without seeing her. 



The following are some of my notes : — 



Marcli 1st, 1897. — Saw Venus at 2 p.m., the sun being 

 obscured by a cloud, and kept her in view till dark. Made 

 some telescopic observations in the evening. 



2Iarch 2nd. — Saw Venus at 2.15 p.m. 



March Sn/.— Saw Venus at 2.30 p.m. 



March Gth. — Saw Venus at 1.80 p.m. Sky hazy, sun 

 shining. 



March lOth. — Saw Venus at 11.45. I could see her 

 quite distinctly through glass. 



March 12?/i.— Saw Venus at 11.80. 



March VAth. — Saw ^'enus at 10.40. 



March nth. — Saw Venus at 3.5 p.m. 



March 18th. — Saw Venus at 11.40. 



Owing to the weather having been unfavourable since 

 the last date, I have only been able to obtain glimpses. 



THE SWIFT'S NIGHT-FLIGHT. 



By Charles A. Witchell. 



DURING June and July, dwellers in places where 

 the swift abounds may investigate its recently 

 discovered habit of soaring upward at evening 

 and (apparently) spending the night in the sky. 

 This interesting incident may be observed in 

 June more easily than in July, because the evening sky is 



clearer in the former month than in the latter. It was 

 just ten years ago that observers in England first noticed 

 this extraordinary behaviour on the part of a diurnal 

 British bird ; and during that cloudless Jubilee June 

 three persons were watching, night after night, the scaring 

 swifts. 



One of these observers was Mr. Aubrey Edwards, son of 

 the vicar of Orleton, E.S.O., Herefordshire, who often saw 

 the swifts from Orleton Church depart upward at night ; 

 and he, with bis father and brother, remained in the 

 churchyard until 10.30, or even 11 o'clock, watching for 

 the birds, which did not return. There were about forty 

 of these ascending swifts, which Mr. Edwards justifiably 

 conceived to be males ; and other swifts remained in the 

 nests. ■ 



In the same month Mr. Douglas Brodie, of Croydon, 

 was making similar observations on the colony of swifts 

 which lived under the eaves of the houses in the centre of 

 that town — as appears from his reply to a query of the 

 writer at a later date. " A certain number of the colony, 

 after the rest have gone to roost, .go soaring up in circles 

 with a peculiar quivermg of the wings, till they go clean 

 out of sight. With field-glasses I have seen them nearly 

 a minute longer." ! 



On the 10th June, 1887, the writer was watching a large 

 flock of swifts from a garden halfway up Stroud Hill, in 

 Gloucestershire. The air was very clear, and the swifts 

 whirled across and across the sky. The sun had set, 

 but the birds did not descend. They finally went 

 right up out of sight. On the 21st the swifts at 

 Stroud exhibited the same wonderful behaviour, which 

 was recorded.:]: 



Since then I have every year watched for the upward 

 night-flight of the swifts ; but as the flights occurred at a 

 rather inconvenient time for observation, there were often 

 several successive evenings on which nothing of the kind 

 was seen. Often, also, the birds would fly away towai'ds 

 the horizon, though when they did this late in the evening 

 their course was generally an upward one. They were, 

 however, no less inclined to a lofty flight on a cloudy 

 night than on a clear one ; and I often saw them vanish 

 into the clouds. But this never happened when the air 

 was very thundery. 



It is convenient to watch the swifts from a somewhat 

 elevated spot, so that they may be kept within view aa 

 continuously as possible, since, if they pass out of the 

 field of vision at a distance, it is almost impossible to 

 find them again. It is also desirable to have a support 

 to lean upon, for without this the constant gazing 

 towards the zenith becomes very tiring, especially if field- 

 glasses are used. It is not often that the birds can be 

 seen during the whole of the upward flight ; they generally 

 swing around in wide circles for some time, and pass 

 out of sight towards the horizon, after which the 

 repeated cry, xwee ree, first indicates their return. The 

 whole incident, as it generally occurred, may be described 

 as follows : — 



The sun has set, and most of the small birds have retired 

 for the night, though the sparrows are still noisy in the 

 creepers on the house. IMost of the swifts are flying low 

 over the meadows, but some are in the sky ; and of these 

 a few are chasing others, and performing those magnificent 

 swoops by which it appears that the males drive the 

 females to their nests. Certain it is that the pursuing 

 birds (always acting singly) chase particular individuals, 

 whose course they follow at a greater altitude, but always 



Nature, 27tli October, 1887. + The Field, 18th May, 1889. 

 X The Field, No. 1851. 



