NOVEMBER 2 j, 1905] 



NA TURE 



87 



principle of interference. By a comparison of the two sets 

 of values, the ratio of the litre to the cubic decimetre was 

 found in two determinations to be 1-000026 and 1000029 

 respectively. The error on the kilogram is thus +26 to 

 + 29 milligrams. 



Messrs. Swan Sonnenschein and Co., Ltd., have pub- 

 lished a third edition of "Sanatoria for Consumptives," 

 In Dr. F. Rufenacht Walters. The book, the f.rst edition 

 of which was reviewed in Nature for July (>, 1899 (vol. 

 1\. p. 221), gives a critical and detailed description, together 

 with an exposition, of the open-air or hygienic treatment 

 of phthisis. 



Dr. H. C. Vogel, director of the Astrophysical Observ- 

 atory at Potsdam, has edited the third edition of Newcomb- 

 Engelmann's " Populare Astronomic,'" published by Mr. 

 \V. Engelmann, Leipzig. Many additions have? been made, 

 both to the text and illustrations, particularly in the sec- 

 tions devoted to spectrum analysis, photometry, photo- 

 graphy, and other branches of astrophysics ; and the whole 

 work has been satisfactorily revised. Short biographies of 

 deceased astronomers from Thales to Keeler, arranged 

 according to their years of birth, are given near the end 

 of the volume. 



We have received from Mr. H. K. Lewis, 1 36 Gower 

 Street, W.C., a copy of No. 23 of his Quarterly List of 

 additions to the circulating library. The list contains 

 more than 100 titles, and includes several important new 

 books and new editions on the various subjects covered 

 In the library. There are brief notes to most of the books 

 which, while not pretending to give the subscriber an 

 exact idea of the book, enable an opinion to be formed 

 on its general scope. On looking through the books in- 

 cluded we notice that, since the first number appeared, 

 considerable extension in the scope of the library has taken 

 place. The library has been long known as a useful 

 medium for the supply of medical literature, and the 

 inclusion of all branches of technological and general 

 scientific books, commenced some two or three yens ago, 

 should add to its value. 



OUR ASTRONOMICAL COLUMN. 



Discovery of a Comet, 1905b. — A telegram from the 

 Kiel Cenlralstelle announces the discovery of a comet bv 

 M. Schaer at Geneva on November 17. At 8h. 7.8m. 

 iM.T. Geneva) the position of the comet was 



R.A.=4h. 22m. 32s., dec. = +86°. 

 The apparent daily movement of this object is given as 

 — 54° in R.A. (i.e. 3b.. 36m.) and — i° in declination. 



A second telegram from the same source announces that 

 the comet was observed at Bamberg on November 18-075. 

 The position, at 6h. 50.6m. (Bamberg M.T.), was 

 R.A.=oh. 58111. I9-5S., dec. = +So° 40' 5". 

 It thus appears that this object was first seen near to 

 Polaris, and is now travelling quickly down through 

 Cepheus towards Cassiopeia. 



Nova Aouil.-e No. 2. — The results of a number of 

 observations of Nova Aquilre are recorded in No. 4052 of 

 the Astronomische Nachrichten. 



On September 29 Prof. Wolf recorded the magnitude 

 of the Nova as 011-9-7, which indicated scarcely any 

 decrease in the brightness since September 17. 



A photograph, taken on October 16 with fifty-six 

 minutes' exposure, showed, however, that the Nova's 

 magnitude had decreased to io-8, that is to say, it had 

 fallen about 12 magnitudes in seventeen days. On this 

 photograph the image of the Nova is surrounded by a 

 faint uneven halo 1' or 2 ' in diameter. 



The Tenth Satellite of Saturn. — No. 9, vol. liii., of 

 the Harvard College Observatory Annals contains an 

 account, by Prof. W. H. Pickering, of the discovery of 

 Saturn's tenth satellite, to which the name Themis has 

 been allotted. 



So far no variation of the satellite's brightness has been 

 detected, its magnitude remaining constant at about 175. 

 As this magnitude is beyond the power of existing tele- 

 scopes, the satellite can never be observed visually until 

 more powerful instruments are available. The probable 

 diameter of Themis is aboul 38 miles ; the orbit of the 

 satellite is inclined about 39°-i lo the ecliptic, and its 

 eccentricity and semi-major axis are about 023 and 



906, miles respectively. The period of revolution is 



2085 days. As the observational data are, as yet, so few, 

 all the above values are to lie considered as only approxi- 

 mate. A drawing accompanying the description represents 

 the orbit diagrammatically. 



Owing to its great eccentricity, the orbit of Themis 

 crosses the orbits of both Hyperion and Titan, and, when 

 near to these bodies, the newly discovered satellite must 

 suffer enormous perturbations, the results of which are 

 disi ussed in Prof. Pickering's paper. 



The Evolution of the Solar System. — Another 

 alternative to Laplace's theory of the formation of plane- 

 tary systems is suggested in an article by Mr. F. R. 

 Moulton, of Chicago University, in the Astrophysical 

 Journal for October. In 1900 Ibis writer and Prof. T. C. 

 Chamberlin examined the older hypothesis from the 

 dynamical standpoint, and found so many conclusive con- 

 tradictions as to lead them to abandon it. 



The theory now suggested supposes that the planets and 

 their satellites have been formed around primitive nuclei 

 of considerable dimensions existing in a spiral nebula 

 probably similar to these which Prof. Keeler showed to 

 be many times more numerous than all the nebula.' of 

 ether types. 



The growth of each nucleus was caused by the gradual 

 accretion of smaller masses, and the method of this 

 growth which is suggested accounts for all the different 

 types of bodies now found in the solar system, and for 

 their present motions and velocities, on dynamical 

 principles. 



The original spiral nebula is supposed to have been 

 formed bv the near approach of another star to the body 

 which is now our sun. This exterior attraction set up 

 tides in the solar matter, and, being continued, actually 

 caused immense masses to be ejected and drawn out into 

 the spiral form. On this assumption the spiral would 

 emerge from the central nucleus in two directions, on 

 opposite sides, and this is the form generally shown on 

 photographs of such nebula?. 



Mr. Moulton 's paper considers at length the explanation, 

 on this hypothesis, of the existing conditions, and a fuller 

 exposition of the theory is promised in a new work which 

 is to be published shortly. 



Catalogue of Variable Stars. — No. 7, vol. liii., of the 

 Harvard College Observatory Annals contains a second 

 supplement to the provisional catalogue of variable stars 

 which was issued in a previous volume of the Annals. 

 The original intention of the Harvard authorities was to 

 publish a supplement, similar to the one issued in 1903, 

 every five years, but the large number of variables recently 

 discovered renders a change of plan necessary. More than 

 400 variables are included in the present supplement, many 

 of them belonging to the nebulous regions investigated by 

 Miss Leavitt. 



During 1904 the number of variable stars was increased 

 bv 503, of which 431 were discovered photographically at 

 Harvard. The card-catalogue of variables which is being 

 compiled at Harvard now comprises about thirty-five 

 thousand cards. 



Star Calendar for 1906. — We have received a copy of 

 a very useful star calendar compiled by [H.P.H.], and 

 published bv Messrs. Hirschfeld Bros. The calendar 

 consists of four cards designed to hang on the wall for 

 ready reference. Each card contains the ordinary date- 

 calendar for the quarter, a table showing the positions of 

 the planets in regard to the constellations, and a star map 

 so marked that the constellations and stars which may be 

 observed on any evening during the quarter, may be 

 instantly recognised by their relative positions in regard 

 to the cardinal points and to the zenith. The price of the 

 calendar is 15. net. 



NO. 1882. VOL. 7 3] 



