October 14 190Q' 



NA TURE 



46: 



In Geography and Travel. — " The Basutos : the Moun- 

 taineers and their Country," Sir Godfrey Lagden, 2 vols., 

 illustrated (Hutchinson and Co.); "Medieval Researches 

 from Eastern Asiatic Sources : Fragments towards the 

 Knowledge of the Geography and History of Central and 

 Western Asia, from the Thirteenth to the Seventeenth 

 Century," E. Bretschneider, 2 vols. (Kegan Paul and Co., 

 Ltd.). In Mathematics and Physical Science. — New 

 volumes of the International Scientific Series : — " Music : 

 its Laws and Evolution," J. Combarieu ; and new editions 

 of " Light and Photography," Dr. H. Vogel and A. E. 

 (iarrett; and "Colour-blindness and Colour-perception," 

 C. \V. Edridge-Green, illustrated ; also " An Easy and 

 Concise Guide to the Starry Heavens," D. M'Ewan, 

 illustrated (Kegan Paul and Co., Ltd.). 



OUR ASTRONOMICAL COLUMN. 



Ephkmeris for Hallev's Comet, 19091:. — A corrected 

 ephemeris for Halley's comet is published by Mr. 

 Cromnielin in No. 4359 of the Astroiwinische Nachrichten 

 (p. 249, September 28). This ephemeris, like that pub- 

 lished in No. ^330 of the same journal, is based on the 

 elements published, for the .Astronomische Gesellschaft 

 prize, under the pseudonym " Isti mirantur stellum," 

 Messrs. Cowell and Crommelin, it transpires, being the 

 calculators. The new observalions do not yet cover a 

 suHliiently long arc to permit of an independent deler- 





luinaLion of the orbit, but they do show that the previously' 

 published elements are correct e.\cept tiiat the date of peri- 

 helion passage must be advanced 34 days, thereby making 

 it 1910 April 200 (G.M.T.) ; this modification has been 

 taken into account in preparing the present ephemeris, 

 which covers the period August 28 to December 26 in 

 five-day steps. An extract follows : — 



From this we see that the comet is at present In the 

 northern limits of Orion, and is some 280 and 230 million 

 miles from the sun and earth respectively ; also that it 

 is approaching the sun and the earth at the respective 

 rates of about 1-12 and 27 million miles per day. The 

 accompanying chart shows its positions in relation to the 

 constellations so far as Mr. Crommelin 's ephemeris gives 

 them. 



Ch.axges on M.ars. — In No. 4359 of the Astronomische 

 Nachrichten, M. R. Jonckheere, of the Obscrvatoire d'Hem 

 f|Roubai.\), gives a drawing of the south polar cap of 

 Mars, executed on September 2, showing the new " land " 

 which he discovered in longitude 120°. He points out that 

 the crevasse and greyish region observed by M. Jarry 

 Desloges are produced by the emersion of the two 

 ■' lands," Argyre II. (longitude 60°) and the new one, from 



NO. 2085, VOL. 81] 



the polar snows. For the newly discovered area in longi- 

 tude 120° he proposes the name " Stella," suggested by 

 its brilliant appearance. 



In the same journal M. Antoniadi records his observa- 

 tions, on September 19, of the Mer du Sablier, which to 

 him appeared as Dawes recorded it in 1864. As Prof. 

 Lowell's observations and photographs show it of a very 

 different form during the period 1894-1907, M. Antoniadi 

 suggests that periodic changes of form, probably irregular, 

 may take place in this feature. 



A number of interesting observations of the planet are 

 recorded in No. 22 of the Gazette Asironomique, by 

 M. P. L. Dupont, of Hoboken, Antwerp. 



Re.markable Meteors. — No. 22 of the Gazette .Istro- 

 nomiqiie contains the records of three remarkable meteors 

 seen in Denmark during August. The first was at 

 gh. 25m. (C.E.T.) on .August ig, and it was bright enough 

 to illuminate the surrounding landscape. Apparently its 

 actual path was from 12S km. above the town of Sorb, 

 in Zealand, to 30 km. above a point on the coast about 

 22 km. west of Soro ; thus the path was nearly vertical, 

 and the velocity was about 33 km. per second. The other 

 two meteors were seen on the same night at gh. 17m. 

 and gh. 38m. respectively. The former was attended by 

 a noise similar to that made by escaping steam, whilst the 

 second one was extraordinarily slow, and was seen for 

 fifteen seconds, during which it passed, nearly horizontally, 

 from 190°, -1-23° to 152", -(-32°. 



The Urs.\-M.\jor Svstem of Stars. — Following up Dr. 

 Ludendorff's conclusion that the stars 3, y, S, t, and 

 f Ursai Majoris belong to a definite system of stars moving 

 along parallel lines in space, Mr. Ejnar Hertzsprung has 

 investigated the conditions for other stars having similar 

 proper motions, and finds that a number of other stars 

 probably belong to the same system. Among these may- 

 be noted Auriga;, Sirius, a Coronse, 78 Urss Majoris, 

 and Groombridge 1930. while 1: Bootis is suspected. .\ 

 number of the stars, nine out of fifteen given, are double, 

 and a tabulation of the magnitudes and spectral classes 

 suggests a development of spectrum, from one star to 

 anothi^r, with an attendant decrease of brightness (.4stro- 

 pliysical Journal, vol. xxx.. No. 2, p. 135). 



SEARcH-ErHEMERis' FOR Winnecke's Comet. — A Continua- 

 tion of the search-ephemeris for Winnecke's comet is pub- 

 lished by Herr C. Hillebrand in No. 4360 of the 

 Astronomische Nachrichten. As the present southerly 

 declination ( — 20°) is increasing, it is not likely that the 

 comet will be generally observed in the northern hemi- 

 sphere. 



The N.ature of Solar FaculjE. — .An important result 

 concerning the nature of bright faculse seen on the sun's 

 disc is published by M. Deslandres in No. 11 of the 

 Comptes rendits (p. 493, September 13). The main con- 

 clusion is that the vapours in the bright faculic areas are, 

 relatively to the surrounding dark areas, descending. 

 This result has been deduced from the measures of the 

 motion-displacements shown on negatives taken with the 

 Meudon spectro-register of radial velocities, the pure K, 

 line being employed. 



Exhaustive measures of the absolute velocities have not 

 been made, because to measure completely the whole disc 

 on one negative would entail some 36,000 settings, and 

 the Meudon staff is not sufliciently large for such an enter- 

 prise. But the measures of a number of displacements on 

 bright areas near the centre of the disc, where the line-of- 

 sight motions are independent of the solar rotation, indicate 

 that the result is general. A diagram which accompanies 

 the paper shows this result for a faculic area photographed 

 on June 4. 



M. Deslandres discusses this result In comparison with 

 atmospheric movements on the earth, and suggests that it 

 is In accordance with theory. When a mass of vapour 

 descends it becomes compressed, and therefore brighter : 

 when ascending, Its pressure is decreased, and consequently 

 the vapour becomes cooled and less bright. 



The investigation of the nature of spots, on the same 

 lines, has not yet been undertaken, M. Deslandres looking 

 upon spots as a secondary phenomenon following the pro- 

 duction of facute. 



