October 5, 1905] 



NA TURE 



56: 



biographies of famous living* Austrians, Frenchmen, 

 Englishmen, and celebrities of other nationalities. The 

 Englishmen noticed in the volume appear to be politicians 

 as a rule, and, so far as we have tested the book, the men 

 of science and of letters selected for inclusion are neither 

 jiumerous nor particularly representative. 



We have received from Messrs. W. M. J. Brooks and 

 Co., Letchvvorth, Herts, a set of five templates, or curves, 

 iiccurately cut in celluloid, representing respectively the 

 jiarabola, ellipse, hyperbola, cycloid, and cubical parabola. 

 When such curves are required it seems better that a 

 student should make them for himself, but failing this Mr. 

 Brooks's curves mav prove useful in special cases. 'I he 

 .price is I5. each curve. 



OUR ASTRONOMICAL COLUMN. 



Further Results outaine[> rv the French Eclipse 

 Expeditions. — In No. 12 (September 18) of the Cotnptes 

 .rcndiis MM. Deslandres and Andoyer give brief summaries 

 ■of the results obtained by them on their respective e.xpedi- 

 .tions to observe the recent total solar eclipse. 



M. Deslandres directed the Bureau des Longitudes mission 

 .to Burgos, where the actual duration of visible " totality " 

 was curtailed by clouds to one minute, which did not 

 include either the second or the third contacts. The pro- 

 posed photographing of the chromosphere spectrum was 

 .therefore impossible. Photometric observations of the corona 

 wore obtained, and M. d'Azambuja was able to measure 

 .the coronal radiation, obtaining figures which were 

 ■decidedly lower than those obtained by M. Charbonneau 

 in igoo. M. Kannapell obtained four photographs of the 

 ■corona polarised by reflection. M. Blum obtained two 

 jjhotographs of the corona through coloured screens so 

 arranged as to transmit only the gaseous radiation of the 

 prominences. By comparing these with the ordinary photo- 

 ..graphs it will, probably, be possible to determine whether 

 or not the prominences emit a more intense continuous 

 .spectrum than that emitted by the surrounding regions. 



At El-Arrouch, 32 km. from Philippeville, M. Andoyer 

 .simply attempted to obtain as many direct pholographs of 

 ■the phenomena as possible. His instrumental equipment 

 consisted of a photographic objective of 14 cm. {5.6-inch) 

 ■aperture and 60 cm. {24-inch) focal length, mounted with 

 two enlarging cameras which increased the diam.eter of 

 .the image by three and eight times respectively. 



Altogether forty-four plates were exposed, eleven of them 

 'during totality. A negative exposed two minutes before 

 totality shows a reversed image, due to over-exposure, and 

 .-a silhouette of fhe corona. 



Elements of Comet 1886 \TII. — From eighty-six observ- 

 ations of comet 1886 viii., made by various observers 

 'between January 24 and May 20, 18S7, Herr E. Fagerholm, 

 of Upsala, has calculated a set of elements for the orbit of 

 4hat object. These, as given below, appear in No. 4047 

 ■of the Aslronomischc Nachrichteii, together with the details 

 of the computation and of the planetary pertiirbations taken 

 anto account : — 



T =1886 Nov. 2844284 + 000267 (M.T. U.ilin). 



"= 31° 55' 34" 53±iS-'-25 I 



a =258° 13' i"-35± 4"-4i i8S7'0 



'■ = 85° 35' i7"-33+ 3"-84 ) 



log (/ =0'17047I2 + 0'00002I4 



The Figure of the Sun. — In No. 2, vol. xxii., of the 

 Astrophysicnl Journal, Mr. C. Lane Poor publishes the 

 results of an investigation, carried out by him at the 

 Columbia University Observatory, which seem to indicate 

 a periodical variation in the figure of the sun agreeing in 

 phase with the sun-spot curve. On measuring the 

 equatorial and the polar diameters of the solar images on 

 twenty-one plates taken by Mr. Rutherfurd in 1870, 1S71, 

 and 1872, he found indications that during this period the 

 equatorial diameter w^as first increasing and then decreasing 

 with regard to the polar diameter. To check this result 

 he re-investigated the measures made by the German 

 observers whilst adjusting, and determining the constants 



NO. 1875, VOL. yi'] 



of, their heliometers for the transits of Venus in 1874 and 

 1SS2. The 1S73-5 results showed a progressive change 

 similar to that indicated by the measures of the Ruther- 

 furd photographs taken in 1871-2, whilst the 1880-3 helio- 

 meter measures confirmed the photographic results of 

 1870-1. Vet another confirmation was found on measur- 

 ing five solar negatives taken at Northfield (Minn., U.S.A.) 

 during the years 1893-4, '^"^ change in figure being the 

 same as in 1S71-2 and 1873-5. 



Plotting the differences between the polar and equatorial 

 diameters in conjunction with the sun-spot curve, it is seen 

 that the two agree, not on'y in point of time, but also of 

 intensity, the excess of the equatorial diameter occurring 

 at sun-spot maximum. 



F'rom these results it appears that the sun is usually 

 an oblate spheroid, but at times of sun-spot minima the 

 length of the polar axis increases in regard to that of the 

 equatorial diameter, and the solar figure becomes prolate. 



Mr. Lane Poor incidentally suggests that this variation 

 of the solar figure may explain the anomalies in the 

 motions of Mercury, Venus, and .Mars. 



Bibliography of Hallev. — No. 14 of the Bulletin of 

 Bibliography Pamphlets, issued by The Boston Book 

 Company, contains the material for a bibliography of 

 Dr. Edmond Hallev, the second Astronomer Royal, and 

 will be found a useful adjunct to any astronomical library. 

 Reading through the numerous items, one is struck anew 

 by the range and number of Halley's writings. The 

 pamphlet is an extract from No. 4 {July), vol. iv., of the 

 Bulletin of Bibliography publish-'d by The Boston Book 

 Company, and costs 25 cents. 



Observations of Jupiter's Saikllmes. — In No. 4045 of 

 the Aslronomischc Nachrichtcn Profs. -A. -A. Nijland and 

 J. van d. Bilt publish the results obtained from a large 

 number of observations of Jupiter's satellites. 



These observations were made with the 26 cm. L'trecht 

 refractor during the period June 30, i()04-February 17. 

 1905, and in the tabulated results the time of the eclipse, 

 transit or occultation of the particular moon is given, 

 together with the difference between these and the calcu- 

 lated times. 



A Lost Double Star. — .\ remarkable chapter of 

 coincidences is recorded in No. 7, vol. xiii., of Popular 

 Astronomy by Prof. Doolittle, of the Flower Observ- 

 atory, U.S.A. In Sir John Herschel's first catalogue of 

 double stars. No. 165 was described as a 3" pair with 

 a position angle of 330°, its position being given as 

 R.A. = ioh. 26.8m., dec. = -+-12° 32' {1825). In 187S Prof. 

 Burnham directed his attention to the pair, and recorded 

 its position angle as 205°-3, and its distance as 2"-5q. 

 Again in iqoi he observed the double with the 40-inch 

 refractor, and obtained a measure agreeing with Herschel's 

 record ; but in 1902 he could find no trace of the pair 

 observed in the previous year, nor of the star measured 

 bv him in 1878. Observations made this year with the 

 iS-inch refractor of the Flower Observatory failed to reveal 

 the double given by Herschel, but showed a very wide 

 faint pair in the exact position given by him. 



Thinking that Prof. Burnham in iqoi might have con- 

 fused the sign of the declination. Prof. Doolittle turned his 

 telescope to the same R.A. in declination minus 12°, and 

 there apparently found exactly the pair that was wanted. 

 This seemed to have cleared up the mystery ; Prof. Burn- 

 ham had in 1901 observed the wrong star. 



.■\ letter from that observer showed, however, that this 

 is not the correct explanation. 



The truth is that Herschel made a mistake of exactly 

 one hour in recording the right ascension of H. 165, and 

 Prof. Burnham had, unwillingly, made precisely the same 

 mistake in 1901. Thus the latest observation of Herschel's 

 No. 165 shows its position to be R.A. =9h. 31m. 13s., 

 dec. = 4-12° 25' (1880), and its position angle and distance, 

 at the epoch 190538, were 333°-i and 2".04 respectively. 



In 1878 Prof. Burnham, observing in the position given 

 by Herschel, saw a pair which was not identical with 

 li. 165, and in the year 1902 was too faint for him to see. 

 In 1901, repeating Herschel's mistake in the R.A., he 

 observed the true H. 165, whilst in 1905 Prof. Doolittle 

 found a similar pair to IT. 165 in the same declination 

 soutJi and in the R..A. given in mistake by Herschel. 



