320 



NATURE 



[Januarv 14, 1909 



AW Ramsay, Richthofen, and Tvndall. W'c miss, how- 

 over, a number of well-known names, as, for instance, the 

 following, who have occupied the president's chair of the 

 Royal Society : — Sir Joseph Banks, Sir Humphry Davy, 

 Sir Joseph Hooker, Sir George Stokes, Sir William 

 Huggins, Lord Rayleigh, and also the present president. 

 Sir Archibald Geikie. Perhaps the company will be able 

 to extend its collection of portraits by the addition of these 

 and a few other British men of science of world-wide 

 renown. 



The Sclborne Society has revived the old title of its 

 magazine, which will henceforth be called The Selborne 

 Magazine (and Nature Notes), and will be published by 

 Messrs. George Philip and Son, Ltd., 32 Fleet Street, E.C. 

 All communications with regard to the society should be 

 addressed to the honorary general secretary, Selborne 

 Society, 20 Hanover Square, London, as heretofore. 



The January number of Knowledge and Scientific News, 

 which is the first number of the enlarged series, contains 

 a five-page illustrated article on the Cavendish Laboratory 

 and Sir J. J. Thomson from the pen of Dr. A. Wood, 

 who has himself worked in the laboratory for the last half- 

 dozen years. He gives an outline of the history of the 

 laboratory, and points out the prominent position it has 

 taken in the march of science during the last twenty 

 years. Views of the original laboratory and of 

 the e.\tension recently opened by Lord Rayleigh are given, 

 but readers will value most the excellent reproduction of 

 Ihe portrait of Sir J. J. Thomson, in which he has his 

 hand on the commutator of an induction coil and his keen 

 f've on the vacuum tubes in front of him. 



OUR ASTRONOMICAL COLUMN. 



Further Photographs of Morehouse's Comet. — Prof. 

 Barnard describes, and reproduces, more photographs of 

 comet 1908c in the December (1908) number of the Astro- 

 physical Journal (vol. x.wiii.. No. 5, p. 384). The four 

 reproduced were selected because they illustrate so well 

 ihe remarkable changes which took place in the comet ; 

 they were taken on October 14, 15, 16, and 30, 1908. 



These changes have been described before, but Prof. 

 Barnard directs attention to one or two peculiarities of 

 especial interest. .\ comparison of the plates taken on 

 October 15 and 16 appears to indicate that there was no 

 acceleration of the motion of the ejected matter in the 

 direction of the length of the tail. From the photographs 

 taken on the former date it appears to Prof. Barnard that 

 the ejected masses moved southwards at a greater rate 

 than did the comet, thus producing the observed changes 

 in position angle of the various sections of the tail. 



Prof. Barnard believes that the masses forming the tail 

 were actually ejected by the action of the comet itself to 

 a large extent, and states that both in this and in Daniel's 

 comet he observed pulsations of light at irregular intervals, 

 such as might be expected to accompany the violent actions 

 which would eject such masses. He also directs attention 

 to the great difference between the visual and the photo- 

 graphic brightness of this comet ; in a moonlit sky the 

 tail could not be observed visually, yet a good photograph, 

 show-ing an extension of eight or nine degrees, was 

 obtained when the moon was 103 days old. 



According to the measures of the 'photographs taken on 

 October 15 and 16 respectively, the uniform value of the 

 recession of the detached masses was about 3'-5 per hour. 



Search-epiiemeris for Hallev's Comet. — \ search- 

 fphemeris for Halley's comet, submitted by an unnamed 

 competitor for the Astronomische Gesellschaft prize, 

 appears in No. 4295 of the Astronomische Nachrichten 

 (p. 369. December 31, 1908). It gives the computed posi- 

 tions of the comet at intervals of ten days for the present 

 year, and for every fourth day, commencing at January 2, 

 in 1910. Observers should remark that' this ephemeris 



NO. 2046, VOL. 79] 



differs, for the present epoch, from that previously given 

 by Messrs. Cowell and Crommelin, whilst the difference 

 between it and that computed by Dr. Smart (Monthly 

 Notices, March, 190S, p. 394), for January 2, 1910, amounts 

 10 more than 3h. in R.A. and to nearly 4° in declination. 



The Distribution of Eruptive Prominences on the 

 Solar Disc. — Some interesting statements concerning the 

 nature and distribution of eruptive prominences on the 

 sun's disc, and of their relations to spots, are made by 

 Mr. Phillip Fox in No. 4, vol. .xxviii., of the Astrophysical 

 Journal. 



From observations made with the Rumford speclro- 

 heliograph, Mr. Fox deduces that the especially brilliant 

 points in the flocculi adjacent to spots, designated " erup- 

 tions " by Hale and Ellerman, are the bases of eruptive 

 prominences. Evidence of this has accrued from the fact 

 that when these eruptions have been observed near the 

 limb, they have been found to coincide with eruptive 

 prominences projecting above the limb. 



The position of these eruptive prominences in relation 

 to spots leads to the conclusion that the spot is preceded 

 by, and has its genesis in, an eruption ; this appears to 

 be so generally the rule that Mr. Fox thinks it is safe to 

 predict the advent of a spot whenever an isolated eruption 

 is observed. 



An examination of all the Ha spectroheliograms shows 

 that solar vortices are counter-clockwise in the northern 

 and clockwise in the southern hemisphere. 



Mr. Fox suggests that the location of eruptive promin- 

 ences between the members of well-developed spot groups, 

 and their absence in front of the leading spot, may be 

 due, at least in part, to the interference of the whirls 

 circulating around the various spots. 



Double-star Orbits. — The orbits of v Cassiopeife and 

 y CoronjE Borealis are re-discussed, in the light of the 

 more recent observations, by Prof. Doberck in No. 4296 

 of the Astronomische Nachrichten (pp. 383-fi, January 2), 

 and revised elements are given for each. 



According to these elements, the period of the former 

 star is 507-60 years and the eccentricity of the orbit is 

 0-5220, whilst for y Corona? the corresponding figures are 

 81-49 years and 0-3908. 



Errors in Measures of Star Images and Spectra. — 

 Some results of great importance to those concerned in 

 the photographic determinations of stellar positions, and 

 of the wave-lengths of stellar sf>ectra, are published by 

 Prof. Perrine in Bulletin No. 143 of the Lick Observatory. 



The experience of everyone engaged in such work is 

 that the discordances found in the measures are greater 

 than can be accounted for by errors of measurement alone, 

 and, whilst developing the method of determining stellar 

 parallaxes by photography. Prof. Perrine has investigated 

 the source of the outstanding discordances. His results 

 indicate that the irregularity, in size and distribution, of 

 the grains in the photographic film is the chief source of 

 the trouble. Instead of each star image being a regular 

 collection of equally sized grains, it is a complicated and 

 irregular gatherins; of particles intersected bv lanes and 

 vacant spaces, and composed of bodies of different sizes. 

 This irregularity leads to errors of settins:, because the 

 centre of such an agtrlomeration is so indefinite, and may 

 depend more upon the structure of the particular part of 

 the film acted upon than upon true position of the area 

 illuminated. 



PHYSICAL OBSERV.iTIONS OF THE 

 N.iTIONAL ANTARCTIC EXPEDITION.' 

 "yHE series of volumes now being issued by the Royal 

 "*■ Society detailing the scientific observations made in 

 the course of the Discovery expedition should impress upon 

 the public the extent and variety of the problems that are 

 under consideration, as well as inform them of the degree 

 of success that has attended the efforts of those who have 

 had to make the observations in trying circumstances. 

 Many, unfortunately, fail to grasp the real object of such 



t "Phys'cal Observations, with Discussions by Various Authors." Pre- 

 pared under the superintendence of the Royal Society. Pp. v-fi92. 

 (London : Publish d by the Royal Society, 1908.) 



