December 30, 1897] 



NATURE 



207 



observed with other optically active hydroxy-acids and their 

 ethereal salts, but no increase is produced with optically active 

 substances, such as chlorosuccinic acid, which do not contain a 

 hydroxyl group, and indeed a slight diminution is caused in 

 some of these cases. Optically inactive acids, such as mesotar- 

 taric acid, inactive malic acid, &c , are quite unaffected by the 

 addition of these substances. Apart from its high theoretical 

 interest, the phenomenon provides a ready method of dis- 

 tinguishing active substances of low rotatory power from their 

 inactive isomerides. 



The additions to the Zoological Society's Gardens during the 

 past week include a Chacma Baboon (^Cynocephalus porcarius, 

 <J ), a Black-backed Jackal ( Cams viesoinelas, 9 ) from South 

 Africa, presented by Major Haynes Sadler ; a Red-bellied 

 Wallaby {Macropus billardieri) from Tasmania, presented by 

 Mrs. Beaumont ; a Guillemot {Lonivla troile), British, pre- 

 sented by Mr. John Pettitt ; a Yellow-cheeked Lemur {Lemur 

 xanlhoniystax) from Madagascar, a Marsh Harrier {Circus 

 .cntginosiis), European, deposited ; six Summer Ducks {^x 

 sponsa, 5 (J , i 9 ), purchased. 



OUR ASTRONOMICAL COLUMN. 



Astronomical Occurrences in January : — 



January 



2. Meteoric shower irom Quadrans (230° + 52°). 

 h. m. h. m. 



3. 6 59 to 8 16. Occultation of 16 Tauri (mag. 6-5). 

 3. 7 13 » 8 27. „ 17 „ 3 8). 

 3- 8 2 „ 9 II. „ 23 „ 4-2). 

 3. 8 46 „ 10 8. „ 1) „ 30). 

 3. 9 55 » II II- „ 28 „ 6-2). 

 3. 10 I „ 10 59. „ 27 „ 3-8). 

 5. Uranus 52' S. of fi Scorpii. 



5. 12 561013 58. Occultation of 125 ,, 4-9) 



7. 10 57 ,, 12 32. Partial eclipse of the moon. Magnitude 



0157 at iih. 45m. 



9. 8 II ,, 9 8. Occultation of o' Cancri (mag. 5'2). 



lo- 15 53 V 17 4- Occultation of B. A. C. 3398 (mag. 6-0). 



14. 5 Jupiter in conjunction with moon. 11 7° 5' N. 



17. 16 '30 to 17 31. Occultation of B. A. C. 5314 (mag. 5.4). 



17. 18 51 „ 20 I. ,, „ 5347 ,, 5-8). 



18. 7 Saturn in conjunction with moon. fj 5" 40' N. 

 t8. 12 53 to 15 25. Transit of Jupiter's Satellite III. 



20. 831. Minimum of 3 Persei (Algol). 



21. Total eclipse of the sun invisible at Greenwich. Begins 



on the earth generally i6h. 46m., ends 2ih. 53m. 

 23. 5 20. Minimum of Persei (Algol). 

 25. II 56 to 14 52. Transit of shadow Jupiter's Sat. III. 

 25. 16 37 ,, 19 6. ,, Jupiter's Sat. III. 



29. 4. Mercury at greatest elongation (21;'^ 4' W.) 



"Nautical Almanac" Corrigenda.— In a letter to the 

 Journal of the British Astronomical Association, Dr. A. M. W. 

 Downing forcibly impresses upon astronomers the necessity and 

 importance of consulting the page of errata in each issue of the 

 N^autical Almanac. In consequence of the Nautical Almanac 

 going to press four years in advance, any corrections to data 

 influencing the tables gives, of course, slightly modified results. 

 We read, for instance, that " in the first edition of the Nautical 

 Almanac for 1 898 (issued in December 1894) the data are affected 

 by an error which throws out the times of the lunar eclipses to a 

 considerable extent ; in the second edition (issued last April), 

 and in a subsequent edition, now being struck off, this error has 

 been corrected. The correct data are also given amongst the 

 errata on page xiii of the Nautical Almanac 1899. It will 

 therefore be advisable for those interested in these phenomena, 

 should they happen to possess the First edition of the Nautical 

 A manac for 1898, to correct the data for lunar eclipses in that 

 edition by the errata given in the Nautical Almanac for 1899." 



Another correction in the same edition is the position of 

 16 Tauri in the Pleiades, which makes an occultation of this 

 star on January 3 a near approach only. 



Occultation of the Pleiades.— For the third time in 

 less than half a year the Pleiades will suffer occultation by the 

 moon on January 3. As in the case of the occultation which 



NO. 1470, VOL. 57] 



took place last October, all the brighter stars will be occulted 

 with the exception of 16 Tauri (see note on " Nautical Almanac 

 Corrigenda "), and this star, although approaching very near, is 

 just missed. The most interesting occultation will be that of 

 Alcyone (mag. 3*0), the brightest star in the Pleiades, and its 

 disappearance at the dark limb should be seen with the smallest 

 telescope. The times are as follow : — 



Time of disappearance, January 3d. 8b. 46m. G. M. T. 

 ,, reappearance ,, loh. 8m. ,, 



The Iris Gulf will be in the neighbourhood of the terminator 

 where the star disappears. 



The passage of the moon before the Pleiades, although a 

 beautiful phenomenon at any time, in this case loses some of its 

 charm through the brightness of the moon, her age being nearly 

 1 1 days, and consequently the aerial reflection will overpower 

 the fainter stars of this group. 



Partial Eclipse of the Moon. — That the moon is getting 

 into position for eclipsing the sun on January 22 is announced 

 by the fact that she herself is under partial eclipse at the 

 preceding lunation on January 7. The phenomenon commences 

 a little before midnight, and ends an hour and a half after. 



The eclipse is a very small one, its magnitude being only 

 o"i57 (moon's diameter = l). 



The following are the corrected phases as given in the 

 Nautical. Almanac (1898) (see note on ^^ Nautical Almanac 

 Corrigenda.") 



d. h. m. 

 First contact with the penumbra, January 7 10 i '2 p. m. 



,, ,, ,, shadow ,, II 47"4 ,, 



Middlg of eclipse „ 80 34-9 a.m. 



Last contact with the shadow ,, I 22-4 ,, 



,, ,, ,, penumbra ,, 386 ,, 



New Investigations of ;3 Lvr.«. — Prof. A. Belopolsky 

 has recently completed a new series of photographs in connec- 

 tion with the spectrum variations of j8 Lyrae ; and his paper on 

 ' ' New investigations of the spectrum of Lyrse " appears in the 

 Astrophysical Journal, November 1897. In all, twenty-six 

 photographs have been taken corresponding to all the phases of 

 brightness, and the results are especially interesting since an 

 "iron comparison" has enabled him to determine the velocity 

 of the system with respect to the sun, and also the radial 

 velocities at different parts of the orbit. 



The dark line at K 4482 has been utilised in making all the 

 measures, for this line changes but little in appearance, whilst 

 the lines A. 4471, Hys and Hy undergo great variations. 



From measures made of the above line, with the iron com- 

 parison as datum lines, he finds that the proper motion of the 

 system = -2'00 geographical miles, and the maximum radial 

 velocity is about 25 geographical miles. Moreover, the 

 curve of radial velocities shows that the changes of brightness 

 may be sufficiently well explained by an eclipse ; for the times of 

 radial velocity = o are very close to the times of principal and 

 secondary minima. His description of the cyclical changes 

 which take place in the appearances of the lines at .\X 4471 and 

 4482, and the reappearance of certain additional lines at parti- 

 cular phases agrees remarkably well with the Kensington results, 

 which, it may be remembered, showed that of the components 

 producing the dark lines, one was like Bellatrix, and the other 

 gave a spectrum similar to that of Rigel. 



The Atmospheres of Planets. — Dr. Johnstone Stoney's 

 name has long been connected with an important theorem in 

 molecular physics, which may be thus stated. The atmosphere 

 round any planet will extend to a height determined by the 

 force of gravity on that planet, arid if the speed with which the 

 molecules move in that atmosphere exceed a critical velocity, 

 they will escape from the planet and move independently in 

 space. In the Transactions of the Royal Dublin Society, 

 November 1897, Dr. Stoney has given in some detail his full 

 views on this subject, and substituted better numerical results 

 for those originally given in scattered scientific papers, by basing 

 them on the fact that helium, whose density is twice that of 

 hydrogen, can, and does, escape from the earth. It is contended 

 that helium is continually being supplied to the earth's atmo- 

 sphere from hot springs, that it exhibits no tendency to combine 

 with other elements, and since no trace of it can be found in the 

 atmosphere, it escapes above, as rapidly as it enters below. 

 Water vapour, on the other hand, remains on the earth, and 

 consequently limits of speed cm be assigned between which 



