256 



NATURE 



LOCTOBER 20, 192 I 



Our Astronomical Column. 



The Lunar Eclipse of October 16. — The three 

 interesting phenomena of the present year — the solar 

 and lunar eclipses and the occullation of Venus — have 

 all been favoured with line weather in London. The 

 chief interest of the lunar eclipse on October 16 was 

 the varied colouring of the shadow. The outer por- 

 tion was bluish- or slate-grey, the inner portion 

 decidedly ruddy. It is not difficult to give an ex- 

 planation ; the light reaching the outer portion needed 

 only a small amount of refraction, and passed 

 through the higher regions of the earth's atmosphere, 

 sufTering but little absorption, while that near the 

 centre of the shadow underwent large refraction, 

 and must have passed close to the earth's surface, so 

 that only the long red waves could get through. 

 Some have reckoned this as a dark eclipse ; the 

 present writer would class it as of average character, 

 having seen both darker and brighter eclipses. There 

 was a large amount of lunar detail plainly visible in 

 the outer region of the shadow ; a Greenwich photo- 

 graph with 40 seconds' exposure showed the Maria 

 and bright rays conspicuously. Two of the predicted 

 occultations were successfully observed at Greenwich. 

 The sky near the moon was too bright to permit the 

 others to be seen. 



Reform of the Calendar. — The Astronomical 

 Union will meet next year in Rome, and among fhe 

 committee meetings that will be held there is one 

 on calendar reform. This committee is presided over 

 by Cardinal Mercier, and includes Sir F. W. Dyson 

 and Prof. Sampson from Great Britain, MM. 

 Bigourdan and Deslandres from France, M. Lecointe 

 from Belgium, and Prof. Campbell from the United 

 States. The main outlines of the reforms to be dis- 

 cussed include a more uniform arrangement of the 

 lengths of the months, alteration in the position of 

 the leap day (the end of the year would be far more 

 convenient from the point of view of astronomical 

 tables), and making the incidence of the week-days 

 the same every year by placing one day a year (two 

 in leap year) outside the weekly reckoning. The 

 further question of the fixation of Easter may be 

 raised, but the committee will, of course, not attempt 

 to make any change without seeking ecclesiastical co- 

 operation. The question of calendar reform has been 

 mooted for many years, but it is much easier to recog- 

 nise the inconveniences of the present system than 

 to agree on an alternative one. 



The Spectrum of ^ Cassiopel^. — Major W. J. S. 

 Lockyer and Mr. D. L. Edwards contribute a paper 

 on this spectrum to the June Monthlv Notices. They 

 show that it is intermediate between those of a Cygni 

 and 7 Cygni. Thus the hydrogen lines and the 

 enhanced lines of manganese and iron progressively 

 weaken from a to 7, while the remaining iron lines 

 and the enhanced lines of titanium progressively 

 strengthen. Seven stars are indicated with spectra 

 almost exact replicas oT that of Cassiopeiae, includ- 

 ing Canopus and a Leporis. Eight other stars are 

 indicated with spectra intermediate between those of 

 <f> Cassiopeiae and 7 Cygni ; they include the two 

 Cepheid variables, r; Aquilae and 8 Cephei ; it is 

 further stated that the spectra of these two approach 

 that of (p Cassiopeiae at maximum, and that of 7 Cygni 

 at minimum. Reasons are given for inferring that all 

 the stars discussed are giants, with temperatures highest 

 in the a Cygni type and lowest in that of 7 Cygni. 



The paper also discusses the differences between 

 the spectra of giant and dwarf stars of spectral type F, 

 Procyon being taken as a representative of the 

 dwarfs. The hydrogen lines are much sharper in the 



NO. 2712, VOL. 108] 



giant stars, and the enhanced n etallic lines more 

 pronounced. 



Reproductions are given of five of the spectra lis- 

 cussed, and it is also pointed out that the research 

 has some importance in connection with the inter- 

 pretation of the spectra of novae, the earlier stages 

 of which resemble the o Cygni type. 



Minor Planets. — Astr. Nach., No. 5122, contains 

 an important research by Edzard Noteboom on the 

 perturbations of Eros, in continuation of work on the 

 subject by Prof. Witt, the discoverer of Eros. The 

 actions of Mercury, Uranus, and Neptune, though 

 almost insensible, are included for completeness. The 

 observations of eleven op|X)sitions, from 1893 to 1914, 

 are compared with theory and twenty-four normal 

 places formed. After correcting the earth's mass, the 

 comparison shows that the largest discordance is 4", 

 most of them being under 2". The research was 

 undertaken mainly to investigate the large terms pro- 

 duced by the earth, and thus obtain a correction to 

 its mass. The combined mass of the earth and moon 

 was found to be i/(328370± 102), leading to a solar 

 parallax of 8-799". 



It is important that Eros should be well observed 

 at every opposition. Only two observations were 

 available in 1903. It is still of magnitude ii|, and a 

 continuation of Mr. Seagrave's ephemeris for Green- 

 wich midnight is given : — 



Oct. 



The same issue of Astr. Nach, contains an investiga- 

 tion of the orbit of the planet 887 Alinda. It was dis- 

 covered four years ago by Prof. Wolf, and approaches 

 closely to the earth's orbit in perihelion, but has large 

 eccentricity ; as its period of four years is about one- 

 third of Jupiter's period, the perturbations by that 

 planet will be large. They have been investigated by 

 Mr. K. Schiitte, who gives a search ephemeris for the 

 present return. The recovery of the planet is desir- 

 able, but as the magnitude is 13-3 and the declination 

 south, it is useless to give the ephemeris here. 



The Centenary of " Astronomische Nachrichten." 

 — Astronomische Nachrichten, founded in 1821 by 

 Schumacher with the encouragement of Gauss, has 

 celebrated its centenary by the publication of a re- 

 markable " Jubilaumsnummer," which contains 

 articles bv astronomers in all the continents, who join 

 in expressing appreciation of the valuable work that 

 this publication has done for astronomy. It has 

 from the beginning exhibited a cosmopolitan spirit, 

 aiming at the general and rapid diffusion of important 

 information, and giving a large portion of its space 

 to articles from other countries thari its own. As 

 Mr. R. T. A. Innes sr.ys in a cordial message : "Con- 

 tinuitv has been maintained ; the Astronomische Nach- 

 richten is in 192 1 what it was in 182 1, the astro- 

 nomer's newspaper, its columns ever open for astro- 

 nomical news from any part of the world." 



One of its features has been the absence of fixed 

 davs of publication, all important communications 

 being published with the smallest possible delay. It 

 has, however, conformed almost exactly to an averdge 

 weeklv interval. The periodical has been invaluable 

 to workers in the special lines- of romet and minor 

 planet observation, and the advance of knowledge in 

 these branches is largely due to its aid. 



The following is a list of the principal contents of 



