August 2, 1906] 



NA TURE 



341 



SOME RKCKST ASTRONOMICAL UORKS.'^ 



T^lIK appearance of another star catalogue from the 

 ■'• Radcliffe Obbervatory shows how loyal that institution 

 lias leniaini'd to the traditions that Main and Siune re- 

 ceived from Johnson and the earlier observers. The 

 result is in every way worthy of those traditions. Other 

 duties may have divided the attention of the director. 

 The maintenance of the observatory in the first rank has 

 demanded within the last few years that new and larger 

 instruments should be erected, and the adjustment of these 

 has necessarily ta.xed the energies of the small staff at 

 the observers' disposal. Hut these imperative tasks have 

 only had the effect of diminishing somewhat the number 

 of stars observed. The accuracy and the independence of 

 the observations, which have ever been a feature in the 

 Radcliffe meridian measures, have in no whit suffered. 

 In these respects the tradition of the observatory has been 

 unflinchingly upheld. 



The introduction to the volume shows that the stability 

 of the instrument has been increased by structural alter- 

 ations. The examination of the division errors, that 

 tedious and laborious work, involving in this case more 

 than ten thousand readings of the circle, has been man- 

 fully tackled with apparently greater care than Stone 

 bestowed upon this fundamental work. The pivots have 

 been tested by an apparatus that Dr. Rambaut himself 

 has perfected. 'I'he results are apparently quite satisfactory. 

 Finally, we are brought face to face with that troublesome 

 R-D correction, the origin of which defies satisfactory 

 €.\plan;ition, as its treatment ta.xes ingenious applications. 

 The method employed at Oxford is not the same as that 

 which recommends itself to the authorities at Greenwich. 

 At the foriner observatory no correction for this discord- 

 ance has been made to the direct measures, the whole 

 difference being itpplied as a correction to the reflexion 

 observations in order to render the two series homogeneous. 

 In the (ireenwich observations of zenith distance, a cor- 

 rection is .applied which has practically the effect of making 

 the final result a mean between the direct and reflected 

 observations. One may not say that it is a consequence 

 of these dilTeient methods of reduction that the declin- 

 ations obtained at Oxford and Greenwich show systematic 

 differences. But when a comparison between the star- 

 places common to the two catalogues (Radcliffe, iqoo, and 

 Greenwich, iSgo) is instituted, a systematic discordance 

 is disclosed, the greater portion of which can be removed 

 by reducing the (ireenwich and Radcliffe observations in 

 substantially the same manner. The zone catalogue of 

 Albany .also includes a large number of stars that have 

 been observed at Oxford. A comparison between these 

 two catalogues is most satisfactory. The difference 

 between the two is practically the same as between Albany 

 and Romberg's Pulkova catalogue. Of the accuracy of 

 this latter Prof. Auwers has spoken in the highest terms. 

 We may offer our congratulations to Dr. Rambaut on the 

 successful completion of a heavy piece of work, and express 

 the hope that the large equatorial, the mounting of which 

 has interfered so much with, the progress of his meridian 

 measures, will amply fulfil its early promise. 



Th" parcel from Groningen contains specimens of those 

 laborious calculations to which the astronomers of that 

 University are so much att.ached, and by which other 

 astronomers have profited. Prof. Kapteyn here gives the 

 results of his discussions of the proper motions of the 

 greater part of the Bradley-.Auwers stars on different 

 assumptions of the value of the precessional constant, 

 the position of the solar apex, and of systematic correc- 



1 "Catalogue of 1772 Stars rhieflv compri.eH within the Zone 85-90 

 N.P.D. for the Epoch 1000. deduced from Ohscrvations made at tt-e 

 Radcliffe Ohservalory, i!.vford, during the years 1894-1Q0;?. under th** 

 direction of Prof, Arthur A. Rambaut. F.R.S. Pp. xxxvi + 8i. (Oxford: 

 Henry Frowde, too6.) 



" PuhUcatlons of the Astronomical Lahoratiry at Groningen." Edited by 

 Prof J. C. Kapteyn. Components of the Proper ^^otions and other quanti- 

 ties for the Stars of Bradley. Tables for Photographic Parr Ilax-Okerva- 

 tions by Dr W, de Sitter. Some useful trigonometrical formula and m 

 table of goniometrical functions for the four quadrants, by Prof T C. 

 Kapteyn and Prof W. Kap'eyu. (Cronlngen : Hoitsema Bros., 1506.) 



.■•Conrsd'.Astronom;e," par I. uis Maillatd. Tome I. Pp.343. (Paris: 

 Librairie scientifique, .\. Hermann, no date.) Price 7.50 francs 



'"New Theories in Astronomy." By William Stirling. Pp. xvH 336. 

 <London : E. and F. N. Spon, Ltd., igof. ) Price 8s. 6d net 



lions to the proper motions in declination. Of the 3222 

 .tars contained in .\uwers-Bradley, 2640 have been dis- 

 cussed. Satisfactory reasons are given for omitting the 

 remainder, so that the material may be considered ex- 

 hausted. 1 he results, grouped according to the galactic 

 l.ititude of the stars or the type of spectrum, have been 

 made the groundwork of special investigations. Since 

 thi'se have been before the astronoinical world some time, 

 it is not necessary to enter into any lengthy description 

 here. The tables indicate a great ainount of care and 

 industry, and will be useful to those who wish to make 

 independent investigations based on the proper motions of 

 I he stars. 



Dr. Sitter's contribution contains new and useful matter. 

 The tables here arranged show at a glance the times of 

 the year most suitable for making stellar parallax observ- 

 .itions, on the assumption that the method of photography 

 will be adopted and that the plates will be taken near 

 the ineridian. Some tables are also given that will be of 

 u.se in the subsequent reduction of the measures. Profs. 

 J. C. and W. Kapteyn add a collection of differential 

 formulae connected with the solution of spherical triangles. 

 The authors believe that such forinuUc- would be of more 

 general use if the amount of the neglected terms was 

 known with certainty. To remove this difficulty, the 

 f<:rmul;u here given are correct to the squares of the 

 differences. Convenience rather than originality seems to 

 liave influenced the authors, both here and in other formulae 

 ;q)plicable to plane and spherical triangles in which certain 

 <rf the elements are small. .Another table for which we 

 l':ive not yet found any extended use is one giving the 

 trigonometrical functions for each degree in the circle to 

 two places of decimals. But the authors say that mathe- 

 m.itically trained persons have found it so useful in re- 

 lii'ving their inind from mental strain, that they contein- 

 plate publishing a similar table giving the natural 

 trigonometrical functions to three places of decimals for 

 every tenth of a degree throughout the entire circle. 



Such tables might possibly be of service to the readers 

 of the next work on our list, " Cours d'Astronomie," by 

 M. Louis Maillard, though, as the author does not vouch- 

 safe any word of preface, it is uncertain for what class 

 of students his book is intended. The purpose of the book 

 is the more difficult to comprehend since we have but one 

 volume of the work froin which to judge of its aim and 

 extent. But the writer of a text-book on astronomy has 

 to keep within lines which are very well recognised. 

 Especially is this the case when dealing with spherical 

 astronomy. The facts do not materially change or in- 

 crease. The only choice the writer can exercise is to 

 decide between a work of reference which shall be as 

 cncyclopEedic as possible, or a text-book which shall pre- 

 sent to the reader a manageable amount of matter from 

 which he may acquire an adequate grasp of the facts and 

 principles upon which the science is supported. M. 

 Maillard apparently prefers the text-book, and proceeds 

 on the usual unheroic lines. He begins with the derivation 

 of the ordinary formula of spherical trigonometry, to 

 which he adds a few pages giving some elementary notions 

 on the theory of least squares. But these few pages serve 

 no useful purpose, and might have been omitted with 

 advantage. When it is added that the author has some 

 chapters on probleins connected with diurnal motion, and 

 a description of the constellations, it will be understood 

 that he is catering for a class that is not very far advanced 

 in astronomical study. But the chapters on parallax and 

 aberration are generally full enough for all who have not 

 to make any practical application of the theory. Finally, 

 the section on the earth and geodetic measurement is made 

 quite interesting. The book ought to have a ready appreci- 

 ation ainong students in high schools and colleges, and 

 is an advance on some of those which have long done duty 

 in this country, and still enjoy an honoured position. The 

 book is apparently lithographed, but it is very handsomely 

 finished, and the diagrams are new and well reproduced. 



Of a very different calibre and purpose is Mr. Stirling's 

 w'ork. M. Maillard has been developed in an atmosphere 

 of extreme orthodoxy. He is not. and has no wish to be 

 thought, original. His methods have received the sanction 

 of many generations of teachers. For good or for evil. 



NO. 1918, VOL. 74] 



