Supplement to "Nature'' March 13, 1902 



in the matter during the last few years are not satisfied 

 that the square law holds at all speeds, i.e. that the 

 air resistance does not vary as the square of the velocity 

 of the vehicle passing through it ; that when bodies of 

 irregular outline are moved through the air the resistance 

 is not as the square of the velocity, but below 1000 feet per 

 minute it probably varies at a lower rate than the square, 

 at or near 1000 feet the square law is fairly correct, above 

 1000 feet per minute at a higher rate. It is probable 

 that there is a point at which the curve turns over, 

 otherwise it would be difficult to account for the small 

 consumption of petrol on the racing vehicles during the 

 French road races at the very high speeds registered. 



Mr. Beaumont's work as a whole will be found a valu- 

 able one to those interested in these matters. 



THE STELLAR UNIVERSE. 

 The S/ars : a Study of the Universe. By Simon New- 

 comb. Pp. .\i -t- 332. (London : John Murray, 1901.) 

 Price 6j. 

 T N the consideration of a book such as this contribution 

 ^ to "The Progressive Science Series," it is advisable 

 to ascertain the standard by which it is to be judged. 

 For convenience, three classes of scientific books may be 

 distinguished, each with its own criterion. There are, 

 first of all, the te.xt-books of a more or less didactic 

 character, aiming at putting the student in possession of 

 the salient facts of his subject ; then we have the reference 

 books, and in the third class we may place all volumes 

 which aim at presenting aspects of a science in terms 

 which maybe appreciated by the lay as well as the scientific 

 reader. Prof Newcomb's book belongs to the third of 

 these types, for it is intended to convey to cultivated 

 minds a view of the state of knowledge of the various 

 bodies in the stellar universe. The stars are considered 

 individually and collectively in many of their character- 

 istics and relationships, with particular reference to their 

 general properties and the structure of the sidereal 

 heavens. 



It would be impossible for a man of science of such 

 distinguished eminence as Prof Newcomb to produce a 

 book of mediocre quality in all its parts. Several of the 

 chapters in the present volume are original contributions 

 to astronomical knowledge and are not likely to be over- 

 looked in future discussion. As instances we may men- 

 tion the essays on the distribution of the stars and the 

 statistical studies of proper motion. In the treatment of 

 such subjects as these Prof Newcomb \s facile princeps, 

 the result being that good material is selected and 

 satisfactory conclusions are reached. But in the realm 

 of astro-physics he wanders about with less definite aim 

 and purpose, partly trusting to the counsel of friends as 

 to the selection of subjects upon which to concentrate his 

 attention. The result of this eclectic survey is not alto- 

 gether satisfactory. A wide acquaintance with the new 

 astronomy and a perfectly impartial spirit are rare at- 

 tributes among writers on celestial science, but they are 

 none the less desirable, and when they are not manifest 

 the deficiency should be pointed out. This we propose 

 to do, if only for the purpose of showing that there are 

 other points of view beside those occupied by Prof 

 Newcomb. 



NO. 1689, VOL. 65 j 



It is easy to show that the outlook described is not 

 only limited, but also often imperfect. Take, for example, 

 the account of nebuke. About forty lines have been 

 found in the spectra of these bodies, yet Prof Newcomb 

 gives the impression that only four are known, namely the 

 blue and violet hydrogen lines and the two characteristic 

 nebular lines. Moreover, he makes the astounding re- 

 mark that "none of these lines can be certainly identified 

 with those of any terrestrial substance. The supposed 

 matter which produces them has, therefore, been called 

 nebulum.'' This is almost all that is said of the spectra 

 of nebuhc, and it is an incorrect and incomplete state- 

 ment of the facts. The suggestion that the lines at wave- 

 lengths 4341 and 4861 are due to the hypothetical nebulum 

 has nothing to support it and cannot be taken seriously. 

 For the rest, we can only say that astro-physics has pro- 

 gressed much farther in the knowledge of the lines and 

 origins of nebular spectra than is implied in Prof 

 Newcomb's paragraph upon the subject. 



As the whole question of the nature of nebuhc has to 

 be referred to spectroscopy for an answer, a basis so 

 slender as that described is unable to support a satisfac- 

 tory edifice. If all that is known of nebular spectra were 

 bounded by the remarks mentioned, the statement that 

 " the light of a nebula does not come from solid matter, 

 but from matter of a gaseous or other attenuated form " 

 might pass muster among the uncritical. But, in addition 

 to the lines of hydrogen and helium and the flutings of 

 carbon, we have evidence of the existence in nebuke ol 

 the metals iron, calcium and possibly magnesium, thus 

 showing that we are not dealing merely with the perma- 

 nent gases. So far as the spectroscopic evidence is con- 

 cerned, the hypothesis that nebuke consist of meteoritic 

 and gaseous matter satisfies the facts better than any 

 other ; and even the dynamical objections mentioned are 

 by no means " insuperable," as Prof Newcomb describes 

 them. Of course, " the amount of light produced by the 

 collision of two such objects [meteorites] is only a minute 

 fraction of the energy lost." But the remainder produces 

 heat which may be suflScient to vaporise some of the 

 constituents of the meteorites engaged, and it must be 

 remembered that gases glow at a low temperature as well 

 as at a high one. 



The tendency to accept transcendental temperatures as 

 characteristic of celestial phenomena shows itself in con- 

 nection with new stars. We have as the cause of the new 

 star of 1 866 " an outburst of incandescent hydrogen, giving 

 rise to a volume of flame of such magnitude as to be 

 visible at the vast distance of our system." From what 

 is now known of new stars it is probable that the Nova 

 of 1866 had a spectrum of much the same kind as that 

 shown by the new stars which have been observed in 

 recent years. In any case, the " world on fire " theory 

 is obsolescent, if not obsolete. Nova Auriga^ began the 

 reform, for no detailed observations with modern instru- 

 ments had been made before its day. Prof Copeland 

 detected and announced the presence of hydrogen in the 

 spectrum on the first night he observed the star after 

 receiving ithe postcard from Dr. Anderson announcing 

 the discovery of the object. The spectrum was photo- 

 graphed at South Kensington a few days later, and on 

 Februarys, 1892, Sir Norman Lockyer announced to the 

 Royal Society that "the bright lines K, H, h and G are 



