430 Notices respecting New Books. 



by investigators for work done by others cognate with their own. 

 No research institute should be without it. 



The work is not intended to be self-paying, at any rate at the 

 beginning. Very substantial monetary aid has been received from 

 numerous G-overnments, Academies, Scientific Societies, and 

 private individuals. The need for aid still exists we believe, and 

 we venture, in this brief notice, to urge the great claims this 

 enterprise possesses to all the support that can be given it. 



Theoretische Astronomie von Dr. W. Klikkerfues. Third Edition, 

 revised and enlarged. By Dr. H. Buchholz. Pp. xxxviii-h 1070. 

 Quarto, with 67 figures. Brunswick : Er. Vieweg & Son, 1912. 

 Price 50 Marks bound. 



Those who are familiar with the second edition of Klinkerfues' 

 'Theoretical Astronomy/ produced in 1899 by Dr. H. Buchholz, will 

 have a cordial welcome for the third edition of the same work 

 which has recently appeared. 



The former edition differed in several important respects from 

 Klinkerfues' original work on which it was based. The earlier 

 lectures of the series, dealing with the fundamental principles on 

 which the determination of the orbit of a heavenly body depends, 

 were developed at much greater length and with more completeness 

 than in the original treatise. The value of the work was also much 

 enhanced by the addition of an elaborate exposition of Gribbs' 

 Vector Method of Determining an Elliptic Orbit from Three Complete 

 Observations, and of tables designed to facilitate the labour of 

 computing orbits, which, with one exception, were wanting in 

 the original. 



The third edition now before us marks another step in advance, 

 and affords the reader a comprehensive knowledge of the various 

 devices most frequently employed by the astronomer of the present 

 day in determining the orbits of heavenly bodies. It is composed 

 mainly with an eye to practical utility, and the aim of the editor 

 appears to have been, not so much the attainment of mathematical 

 elegance or uniformity of treatment, as to enable the astronomical 

 computer to reach in the most advantageous way the best result 

 deducible from the observational data at his disposal. 



Prefixed to the work is a long introduction in which, inter alia, 

 the writer discusses at considerable length the reasons for an 

 important change in the first lecture. Towards the end of that 

 lecture as it appeared in the second edition, in describing the 

 general problems of planetary motion, it was stated that G-ylden's 

 " Theorie der absoluten Bahn" afforded a satisfactory solution of 

 the perturbation problem and represented the motion for an 

 indefinite time. As is well known, however, Grylde'n's "horistic' , 

 method has been called in question by Poincare and has given rise to 

 a lively controversy, in view of which the references to the subject 

 in the first lecture of the new edition have been entirely modified. 



Amongst the more recent methods of computing the orbit of a 

 planet those of Gibbs, Harzer, and Leuschner are deserving of 

 special mention ; and just as the second edition of this work was 



