15S 



KNOWLEDGE. 



[August 1, 1893. 



but in the reverse direction .... at the same time also 

 our own birds return from the Continent to their nesting 

 quarters in these islands." 



The reason of such migratory movements can scarcely 

 be explained as the result of lack of food and unsuitability 

 of climate, since multitudes of the same species as those 

 which leave pass the winter in the same country. 



An interesting and apparently ioexplicable fact recorded 

 by the British Association Committee, and not alluded to 

 by Mr. Dixon, is a migration westwards from the west 

 coast of Ireland. Thus, in their report for 1887, they 



write : — , 



'• At Rathlin O'Birne (West Donegal) immense tiocks ot 

 birds— starlings, thrushes, and fieldfares— passed nrt^t from 

 December 18th to 28rd. The nearest land to the west ol 

 this rocky island is America. This is not an isolated 

 occurrence. The westerly tiiKht of land birds at stations 

 off the west coast of Ireland has been noticed on other 

 occasions ; the movement is apparently as reckless as that 

 of the lemmings." 



Certain natm-alists have suggested, in all seriousness, 

 that the westward migration of the lemming is m search 

 of the lost Atlantis, to which their ancestors were wont to 

 roam. Will they accept this westward migration of birds 

 as a further illustration of the former existence of tUe 

 Platonic continent ? 



THE FACE OF THE SKY FOR AUGUST. 



By Herbert Sadler, F.R.A.S. 



NEITHER sunspots nor faculs show very percep- 

 tible signs of decrease. Conveniently observable 

 minima of Algol occur at llh. 3'Jm. i'.m. on the 

 11th, and at 8h. 28m. p.m. on the 14th. 



Mercury is too near the 8un during the first 

 portion of the month to be visible, he being in superior 

 conjunction on the 8th. On the 20th he rises at 3h. 31m. 

 a.m!, or Ih. 28m. before the Sun, with a northern declina- 

 tion of 15° 39', and an apparent diameter of 8^", j-o^ths of 

 the disc being illuminated. On the 2.5th he rises at 8h. 

 22m. A.M., or Ih. 40m. before the Sun, with a northern 

 declination of 16° 1', and an apparent diameter of 1^'', 

 ^Vo-tiis of the disc being illuminated. The next morning 

 he"is at his greatest western elongation (18| > On the 

 31st he rises at 3h. 35m. a.m., or Ih. 38m. before the Sun, 

 with a northern declination of 14° 47', and an apparent 

 diameter of fli", fTTijt.hs of the disc being illuminated. 

 While visible. Mercury passes through a portion of Cancer 

 into Leo, without approaching any conspicuous star. 



Venus is an evening star, setting on the 1st at 8h. 33m. 

 P.M., or 59m. after the Sun, with a northern declination of 

 11= 27', and an apparent diameter of 11", t,M'^ o' ^^^^ 

 disc being illuminated. On the I8th she sets at 8h. 13m. 

 P.M., with a northern declination of 8° H', and an apparent 

 diameter of llf", xVot^s of the disc being illuminated. 

 On the 31st she sets at 7h. 45m. p.m., or 57m. after the Sun, 

 with a southern declination of 8° 84', and an apparent 

 diameter of 12^", tVo^Iis of the disc being illuminated. 

 Her brightness at the beginning of the month is about one 

 quarter'of what it will be at the begiiming of next .January. 

 During August she passes from Leo into Virgo, being near 

 the 4', magnitude star ^ Leonia on the 8th, and the 4th 

 magni'tude star o- Leonis on the 12th. On the evenings of 

 the iHth and 19th she is not far from the 3^ magnitude 

 star fi \'irgiuis, and on the 25th she is near the 4 th magni- 

 tude star 1) Virginis, and at the end of the month to the 

 south-west of Saturn. 

 Mars is invisible ; and as Neptune does not rise till after 



midnight at the beginning of the month we defer an 

 ephemeris ol him tdl September. 



Jupiter rises after llh. p.m. at the beginning of August, 

 and is getting into a favourable position for observation. 

 He rises on the 1st at llh. 15m. p.m., with a northern 

 declination of 18° 41', and an apparent equatorial diameter 

 of 87-5", the phase on the p limb being perceptible. 

 On the 19th he rises at lOh. 9m. p.m., with a northern 

 declination of 19° H', and an apparent equatorial diameter 

 of 89'4". On the 81st he rises at 9h. 25m. p.m., with a 

 northern declination of 19° 19', and an apparent equatorial 

 diameter of 40-S ", the phase on the /' limb amounting 

 to 0-4 ". He is in quadrature with the Sun on the 23rd. 

 During the month he describes a short direct path in 

 Taurus, being about 4° south of the Pleiades on the 1st, 

 but without approaching any naked eye star during the 

 month. At halt an hour after midnight on the 29tli a 9-5 

 magnitude star will pass behind the centre of the planet 

 a little to the north, the occultation lasting about four 

 hours. The following phenomena of the satellites occur 

 while Jupiter is more than .S= above and the Sun K° below 

 the horizon : — On the 2nd a transit egress of the shadow 

 of the second satellite at Hi. 5m. a.m., and of the satellite 

 at lb. 26m. a.m. Ou the Gth a transit ingress of the 

 shadow of tlie first satellite at 2h. 25m. a.m., and of the 

 shadow of the third satelliteat 3h. 12m. a.m. An occultation 

 reappearance of the first satellite at 8h. 6in. a.m. on the 

 7th. A transit egress of the first satellite at Oh. 26m. a.m. 

 on the 8tli. A transit ingress of the shadow of the second 

 satellite at Ih. 19m. a.m. on the 9th. An occultation 

 reappearance of the third satellite at Oh. 6in. a.m. on the 

 lOth. An occultation reappearance of the second satellite 

 at Ih. 29m. a.m. on the 11th. An eclipse disappearance 

 of the first satellite at Ih. 29m. 31s. on the 14th. On the 

 15th a transit ingress of the first satellite at Oh. lOm. a.m. ; 

 a transit egress of its shadow at Oh. 59m. a.m. ; a transit 

 egress of the satellite at 2h. 21m. a.m. ; an occultation 

 reappearance of the first satellite at llh. 30m. p.m. Au 

 occultation disappearance of the third satellite at 2li. 40m. 

 A.M. on the 17th. On the 18th an eclipse reappearance of 

 the second satellite at lb. 17m. 56s. a.ji., and its occultation 

 disappearance at Ih. 49in. a.m. On tl;e 21st an eclipse 

 disappearance of the first satellite at 3h. 23m. 16s. a.m. 

 Ou tiie 2;ind an ingress of the shadow of the first satellite 

 at Oh. 41m. a.m., a transit ingress of the satellite at 2h. 4m. 

 A.M., and a transit egress ol its shadow at 2h. 58m. a.m. 

 An occultation reappearance of the first satellite at lb. 24m. 

 a.m. on the 28rd. On the 24th an eclipse disappearance of 

 the third satellite at Ih. Cm. 4s. a.m., and its eclipse re- 

 appearance at Uh. 34m. lOs. a.m. On the 25th an eehpse 

 disappearance of the second satellite at Ih. 39m. 41s. a.m., 

 and Its reappearance at 8h. 58in. 52s. a.m. It is stated by 

 Webb that only four observations of the disappearance and 

 reappearance of the second satellite on the same night are 

 on record. A transit egress of the second satellite at 

 Oh. 52m. A.M. ou the 2(Uh. On the 29th a transit ingress 

 of the shadow of the first satellite at 2h. 35m. a.m.; a 

 transit ingress of the satellite at 3h. 5Sin. a.m. ; an eclipse 

 disappearance of the first satellite at llh. 45m. 28s. p.m. 

 On the 80ih an occultation reappearance of the first 

 satellite at 8h. 17m. a.m. On the 80tli a transit egi-ess of 

 the shadow of the first satellite at llh. 16m. p.m. On the 

 81st a transit ogress of the first satellite at Oh. 37m. a.m. 

 The following are the limes of superior and inferior 

 conjunctions of tue fourth satellite : — Superior, August 

 16tii, 3h. 9m. P.M. ; Inferior, August 8th, 7h. 12m. a.m., 

 25tli, Ih. 38m. a.m. 



Saturn is still just visible in the evening, hut niu.st be 

 looked for in the early twilight to be seen at all. He sets 



