136 



♦ KNOWLEDGE 



[Feb. 13, 1885. 



THE FACE OF THE SKY. 



From Feb. 13 to Feu. 27. 

 By F.R.A.S. 



SOLAR activity seems to iliminish but slowly, and beautiful 

 groups of spots still continue to appear at intervalson the Sun's 

 face. Map. II. of "The Stars in their Seasons " shows the face of 

 the night sky. Mercury and Venus are both morning stars, but are 

 still most indifferently placed for the observer. Mars is invisible. 

 Jupiter, a little to the east of Kegulus, towards which he continues 

 to travel, is now visible all night long, and is — as ho has for some 

 time been — by far the most brilliant and conspicuous object in the sky. 

 He comes into opposition to the sun at 8 a.m. on the 19th, so that 

 he is about as well placed for the observer as ho can be. The 

 phenomena of his satellites occurring during convenient hours of 

 the night, during the next fourteen days, are numerous and in- 

 structive. The student will note that prior to the 19th the shadow 

 of a satellite precedes the satellite itself on the disc of the planet ; 

 and that after the 19th the satellite precedes its shadow (see 

 Knowledge, Vol. V. pp. 12G and 127). On the 14th, then. Satellite 

 II. will reappear from Occultation at 7h. 12m. p.m. On the 10th 

 Satellite III. will disappear in eclipse at 7h. 21ra. JSs. p.m., to re- 

 appear from behind the planet's limb at llh. 9m. p.m. On the 17th, 

 Satellite I. will be eclipsed, igm. 16s. after midnight. On the 18th, 

 the shadow of Satellite I. will enter on to Jupiter's disc at lOh. 5m. 

 p.m., followed by the Satellite casting it only one minute later. 

 The Satellite and its shadow will practically leave the opposite 

 limb of the planet together 25 minutes after midnight. On the 19th, 

 Satellite I. will be occulted at 7h. 15m. p.m. Satellite IV. will 

 reappear from eclipse at 8h. 41m. 52s. p.m. The reappearance of 

 Satellite I. from occultation will occur at 9h.34m. ; and the transit 

 of Satellite II. begin at llh. 3Sm., followed by that of its shadow 

 at llh. 40m. On the 20th, Satellite I. will pass off Jupiter's 

 face at 6h. 51m. p.m., as will its shadow at Ch. 54m. On the 21st 

 Satellite II. will be occulted at Gh. 32ni. ; pass behind the body of 

 the ])lanet into its shadow, and reappe.ar from eclipse at 9h. 33m. 41s. 

 On the 23rd, Satellite III. will be occulted at lOh. 19m. p.m. On 

 the 25th, the transit of Satellite I. will begin at llh. 50m., p.m. and 

 that of its shadow at midnight. On the 2Cth, the same Satellite 

 will be occulted at 8h. 58m., to reappear from eclipse at 

 llh. 26in. 2is. p.m. Finally, on the 27th, the beginning of the 

 transit of Satellite I. may possibly be perceived at Gh. 16m. p.m. 

 Its shadow follows it at Gh. 28m. It passes off the opposite limb 

 of Jupiter at 8h. 35m. ; as does its shadow at 8h. 48m. At 9h. 38m. 

 Satellite IV. enters on to Jupiter's face; followed by its shadow at 

 llh. 34m. p.m. The student is recommended to pay particular 

 attention to this phenomenon ; inasmuch as it is the two outer 

 Satellites which have been most frecjucntly perceived as dark or 

 even black spots on the brilliant disc of the planet. Saturn should 

 be looked for now as soon after dusk as may be convenient ; as, 

 though he is still above the horizon during the working hours of the 

 night, he is slowly, but surely, approaching the West. He still 

 forms a rudely isosceles triangle with ji and J Tauri. Uranus may be 

 found during the later part of the night by fishing almost due east 

 of >i Virginis. Xeptnne is not worth looking for. The Moon is new 

 at 2h. 21m. 8s. in the early morning of the 15th, and enters her 

 first cjuarter at lOh. 31m. a.m. on the 22nd. Four occultations 

 of fixed stars (one of them a notable one) occur during the 

 next fourteen days. The first is of the 5th Mag. Star, 

 38 Arietis, which will disappear at the Moon's d.ark limb on the 

 20th at 7h. 41m. p.m., at an angle from her vertex of 211°, re- 

 appearing at her bright limb at 8h. Im., at a vertical angle of 246°. 

 (.)n the 22nd Aldebaran will be occulted, and to this phenomenon 

 the attention of the student is particularly directed, inasmuch as 

 this is the star which has been most frequently seen projected on 

 the Moon's limb. It will disappear at 5h. 17m. in the late after- 

 noon at the dark limb, at a vertical angle of 20', and reappear at 

 5h. 50m. p.m. at the bright limb, at an angle of 330° from the Moon's 

 vertex. On the 23rd 130 Tauri, a sixth magnitude star, disappears 

 at the dark limb at llh. 3m., at a vertical angle of 145°, reappear- 

 ing at the bright one two minutes after midnight, at an angle of 

 288° from her vertex. And, lastly, on the afternoon of the 26th, at 

 3h. 59m., the sixth magnitude star B.A.C. 2872 will disappear at 

 the dark limb, at an angle from the Lunar vertex of 340°, to re- 

 appear at 4h. 21m., at a vertical angle of 280". Up to noon to-day 

 the Moon is in C'apricornus, but at 4 o'clock this afternoon crosses 

 into Aquarius, through which she is travelling until G p.m. on the 

 16th, when she enters Pisces. It takes her until 9 p.m. on the 19th 

 to pass across this great constellation, and at the last-named hour 

 she passes into Aries. This she quits for Taurus at noon on the 

 21st. Travelling through Taurus at midnight on the 23rd she 

 .arrives on the confines of the northern strip of Orion, and by the 



noon of the 24th has passed over this and entered Gemini. She 

 leaves Gemini for Cancer at 2 a.m. on the 20th, and Cancer for Leo 

 at 1 o'clock the next afternoon. Tliere we leave her. 



EPHEJIERIS OF ENCKE'S COMET. 



From Feb. 13 to Feb. 27. 



The short path shown in the above ephemeris starts from a 

 point to the north-west of the 4th mag. star w Piscium 1° 20' due 

 north of which it will be found on the night of the 14th. 



irligrrHanfa, 



Mari^ Twain intends, says the Athetrwum, visiting England in 

 May, for the purpose of giving readings from his own writings. 



The number of passengers between England and France last year 

 was 361,154, a falling off of 70,320, due, of course, to the cholera; 

 182,897 went by w.ay of Dover and Calais, 96,304 of Folkestone 

 and Boulogne, 67,156 of Newhaven and Dieppe, and 14,797 ot 

 Southampton and Havre. 



PiiOTOGR.ipniNG the Lartnx. — Dr. Theodore Stein has devised an 

 ingenious and simple apparatus for taking photographs of the 

 larynx which is likely to be useful in medicine and pathology, 

 since it will enable doctors to study from day to day the changes 

 of laryngeal disorders. It consists of a small incandescent lamp 

 of 10 candle-power fed by a portable battery and cooled by Nitze's 

 system of circulating water. This supplies the light which illumi- 

 nates the throat and larynx. An image of the latter caught on a 

 small mirror is received into a small camera on gelatine-bromide 

 plates, the exposure being regulated by an electro-magnetic device 

 operated by pressing a button. — Engineering. 



The Aeronautical Society of Great Britain (which must be care- 

 fully distinguished from the Balloon Society) proposes to take a 

 practical step towards the attainment of the end for which it was 

 established, by holding an Aeronautical Exhibition at the Inter- 

 national one to be opened at the Alexandra Palace next month. 

 The Aeronautical Exhibition itself will however, not, begin until 

 June. The objects for exhibition will be : — 1. Models of designs 

 for the accomplishment of aerial navigation by mechanical means 

 only. 2. Models of designs for the accomplishment of aerial 

 navigation partly by buo^'ancy and partly by mechanical means. 



3. Models constructed to elucidate either of the two last objects, 

 which are capable of flight and carrying their own motive power, 



4. Machines constructed upon a scale calculated to carry a weight 

 equal to that of a man, upon the principles advocated by the 

 inventors. X.B. — The practicability may be demonstrated by the 

 flight of a model of similar character, and of weight-carrying 

 capacity sufficient to enable a judgment to be formed as to the 

 probable eflSciency of the large machine when actuated by the 

 power necessary for its support and propulsion, whether by manual 

 or mechanical methods. 5. Light motors. X.B. — It may be 

 observed that light motors are in request for other purposes than 

 aerial navigation. But for the latter object it is essential that 

 extreme lightness shall be a condition. Therefore only a motor 

 possessing that qualification in proportion to its power with the 

 smallest consumption of fuel (in the case of steam) or other 

 adjuncts, and capable of workmg up to one horse power at the 

 least for twenty minutes, will be deemed deserving of the prize. 

 6. Balloon.s, navigable or otherwise. 7. Balloon material and 

 appliances for propulsion or otherwise. 8. Kites or other aerial 

 appliances of that cluaracter, for saving life at sea, for traction, or 

 otherwise. 9. Objects of interest connected with aeronautics. 



