April 26, 1906] 



NA TURE 



603 



as necessary as references to the ordinary scientific 

 journals. 



In reading chemical compilations of German origin 

 we are sometimes struck by the scant attention re- 

 ceived by work done in this country, and are often 

 forced thereby to the conclusion that the author's 

 study of English chemistry is limited to the system of 

 abstracts issued by the Berlin Chemical Society. No 

 such fault can be found here ; the author is obviously 

 as much at home in the Journal of the Chemical 

 Society as in the Continental journals, and gives full 

 credit to all results, from whatever source they are 

 derived. 



For Aschan's new book, as a whole, nothing but 

 praise is possible, and the few points to which objec- 

 tions have been made rank as nothing when regarded 

 as raised from the perusal of a book 1200 pages long, 

 which aims at giving a systematic account of the 

 alicyclic compounds. The study of these substances 

 has been mainly carried out at fever heat during the 

 past quarter of a century, and the necessarily ragged 

 way in which the results have been laid before the 

 world in the current journals must have offered 

 immense difficulties to the compiler. 



We cannot close this book, containing as it does 

 a lucid account of one of the most important and 

 intricate sections of organic chemistry, without re- 

 flecting with pleasure that the intense but systematic 

 work which has led, during the last twenty years, 

 to the synthetic building up of such complex molecular 

 structures as those of camphor and of the terpenes 

 has been largely carried out in our own country. 



W. J. P. 



THE SYSTEM OF THE FIXED STARS. 



Der Bait des Fixsternsy stems mil besonderer 

 Beriicksichtigung der photometrischen Resultate. 

 By Prof. Hermann Kobold. Pp. xi + 256. (Bruns- 

 wick : Yieweg und Sohn, 1906.) Price 5.60 marks. 

 TO prove that the stars form a stable system is a 

 problem that has had attractions for many 

 philosophical minds. The problem has not been 

 solved, possibly may not be capable of solution, but 

 the attractiveness of the speculation remains. Analogy 

 with the solar system has suggested, and given sup- 

 port to, such an idea. The harmony that is to be 

 perceived in the ordered motions of the planets, per- 

 mitting countless revolutions to be performed without 

 permanent change or irregularity, might well give 

 rise to the hope that the same principle that governs 

 the solar system could be detected in the larger 

 scheme of the stellar universe. Such an idea would 

 naturally have sway at a time when speculation was 

 little fettered by numerical data drawn from rigorous 

 observation. If there was little evidence to support 

 the notion, there was nothing to contradict it. Kant 

 or Lambert could suggest without difficulty that the 

 stability of the system was secured by each star 

 moving in a definite orbit, which ensured the main- 

 tenance of the general form and arrangement. The 

 influence that that thought has exercised on modern 

 NO I904, VOL. 73] 



investigation is of more importance than the thought 

 itself. To suspect the influence of the Milky Way 

 in the scheme of the Cosmos, and to make its in- 

 vestigation the centre of inquiry, was to bequeath us 

 a legacy which is by no means exhausted. Later- 

 schemes suggested by improved instrumental appli- 

 ances have widened the scope and raised fresh issues,, 

 but the significance of the Milky Way remains.. 

 Similarly with the problem of the sun's motion, which 

 a hundred years ago Herschel solved so satisfactorily, 

 considering the character of his material. Disputed 

 by Bessel and supported by Argelander and a host of 

 later astronomers, the solution has passed through 

 many stages and given rise to novel methods of treat- 

 ment, involving the application of fresh hypotheses. 

 In these later times we have pressed into the service- 

 the results brought to light by the spectroscope, 

 especially difficult of interpretation as they are, and 

 allowing the exercise of much ingenuity. But the 

 essential problem remains the same. The only ques- 

 tion is, What advances have we made in solving the 

 riddle which perplexed earlier investigators? 



In proportion as the problem becomes more and 

 more complicated, either by repetition of similar pro- 

 cesses or the introduction of fresh ones, the greater is 

 the necessity for the examination of the evidence to test 

 its value in combination, and of bringing the whole 

 material to bear in one consecutive argument. This 

 is the task which Dr. Kobold has undertaken, and' 

 in which he has acquitted himself with credit. One 

 may not in every case draw the same conclusion, or 

 with the same certainty, that the author does, but the 

 evidence is at least presented with completeness, and 

 we have the opportunity of bringing our critical' 

 faculty to bear upon the various lines of argument 

 which are marshalled in review. Such a book is in- 

 structive to the tyro and suggestive to the expert. 

 The one may adopt the conclusions which the author 

 has drawn up, as indicating the general position of 

 science towards this problem, the other may see the 

 necessity for pursuing fresh lines of research, or of 

 supporting alternative explanations of the results pre- 

 sented. In any case it is an advantage to see what 

 has been attempted and what has been accomplished. 



The author divides his book into three sections. 

 In the first he describes on broad lines how the facts- 

 which may aid in solving the problem of the con- 

 struction of the universe have been collected. The 

 reader who comes fresh to this subject, without any 

 previous acquaintance, gains an intelligent notion of 

 the manner in which the positions of the stars have 

 been ascertained, and can grasp clearly the supreme 

 importance of an accurate determination of the pre- 

 cession constant when the question of proper motion 

 is considered. The brilliancy and the colour of stars 

 are both discussed, though the practical bearing of 

 the latter point on this particular problem is not 

 very clear, and in any' case is more conveniently dealt 

 with in discussing the spectroscopic observations, 

 which are also brought under notice. Parallax and' 

 stellar distribution are adequately described, and there- 

 fore in this section we get a tolerably complete sketch 

 of the main processes of stellar observation, except in 



