NA TURE 



193 



THURSDAY, Jl'LY 2, 1908. 



DEVhl.OPMENT OF .4.S7'fiOA"0.1/ V. 

 .4 History of Astroiinwy. By W. W. Bryant. Pp. 

 .\iv + 35v (London : Methuen and Co., n.d.) 

 Price ys. 6d. net. 

 r T is somewhat difficult to decide on the attention 

 J- to be devoted to a volume so small as the present 

 .one, as it is from the first apparent that as a " his- 

 Jtorv " justice could only be done even to a few sec- 

 tions of the subject. The intention of the author 

 appears to have been to give a more or less popular 

 account of the evolution and progress of the chief 

 divisions of the science, without attempting to render 

 the storv complete. Starting with a short review 

 of the astronomical notions of the early races, in the 

 first two chapters the various claims to priority of 

 record are examined, the Chinese data purporting to 

 e.\tend back to 2500 i:.c. ; the Indian system has 

 tables, &c., supposed to be based on phenomena of 

 the year 3102 B.C.; Egypt and Chaldea are also r,f 

 very great antiquity, the latter recording the eclipses 

 observed at Babylon in 721 and 720 B.C. In chapters 

 iii. and iv. the advances made by the Greeks and 

 Arabian philosophers are briefly reviewed. The Arabs 

 •excelled in methodical accuracy, and modern astro- 

 nomv owes them an immense debt for the introduc- 

 tion of the decimal notation, replacing the more cum- 

 bersome numerical notations of the Greeks and 

 Romans. 



The end of these two schools brings the record 

 down to the fifteenth century, when the great revival 

 of philosophical thought in Europe commenced to be 

 N\ide!y felt. The work of Copernicus, who was born 

 at Thorn, in Polish Prussia, in 1473, was published 

 in 1543. and practically inaugurated a new era, in that 

 1:he Ptolemaic svstem was shown to be inadmissible, 

 and the new Copernican system soon forced its way 

 to the front, as it explained many phenomena which 

 previously gave difficulty. Copernicus, however, was 

 but a theorist, and it was by Tycho Brahe, born of a 

 noble Danish family in 1546, that the great observa- 

 tional advancement of the sixteenth century was made. 

 The story is then continued, giving the successive 

 advances made in turn by Kepler, Galileo, Newton, 

 Laplace, and the seventeenth and eighteenth century 

 early astronomers Flamsteed, Halley, Bradley, and 

 Merschel. L'p to this stage the treatment has been 

 chronological, but from this point the author, ap- 

 parently finding difficulty in correlating the over- 

 whelming flood of new observations which marked 

 the end of the eighteenth and the whole of the 

 nineteenth century, takes a series of subject divisions, 

 and gives the main features of progress in both theory 

 and observation relating to each. This naturally 

 leads to various redundancies, and we doubt if the 

 non-expert reader will obtain a clear idea of the 

 chronological progress during these later times. 



Chapter xv. is devoted to the modern development 

 of observatories and instruments, w-hich is very in- 

 teresting reading. No mention is rpade, however, of 

 NO. 2018, VOL. 78] 



the great influence on instrument design which has 

 resulted from the use of the horizontal tele-cope in 

 conjunction with a moving mirror of the Foucault 

 siderostat or Lippmann coelostat type, as is done at 

 Paris, London, and at several stations in America. 

 Chapter xvii. deals with the discoveries connected with 

 the physical nature of the sun, the periodicity of the 

 sun-spots, faculae, &c. In the two following chapters 

 the spectroscopic researches in connection with the 

 sun are related from the time that Kirchhoff made 

 his historic observation of absorption in icS5g. Natur- 

 ally the enormous development of this branch of 

 astronomy since the 'eighties has made it impossible 

 for the author to give more than a superficial narra- 

 tion of the progress made, but what he has included 

 is both useful and interesting. 



Chapters xx. to xxvi. deal with the individual mem- 

 bers of the solar system. Most of this calls for little 

 comment; in the chapter on Mars, predominance is 

 given to the " carbonic acid " theory of the polar 

 caps, but as we know from the recent researches of 

 Lowell, it is now conclusively proved that water 

 vapour in quantity does exist on the planet, and it 

 is therefore unnecessary to discuss the more improb- 

 able theory. The concluding remark in this chapter 

 is somewhat ungracious in an impartial review of 

 the history of the subject; scepticism regarding the 

 Lowell Observatory announcements is practically non- 

 existent in the minds of anyone competent to appre- 

 ciate the work done at that institution. Although 

 open-minded in general, remarks like this show a 

 tendency to urge an isolated opinion on matters re- 

 quiring very wide discussion. In general, it may be 

 said that these chapters on the solar system are very 

 well up to date, and a short resume is added giving 

 the more modern theories of cosmogony, in which the 

 simplicity of the original nebular hypothesis cf 

 Laplace has gradually given way to more modified 

 views, no one of which, however, is at present de- 

 finitely accepted. 



Comets, meteors, and the Zodiacal Light are dealt 

 with in chapter xxvii., the various cometarv theories 

 being very ably described without introducing any 

 technicalities. Chapters xxviii.-.xxxii. are occupied with 

 the history of stellar research. The introduction and 

 design of star catalogues of various degrees of pre- 

 cision, down to the great international Carte dit CieK 

 zone work, observations of proper motion and par- 

 allax, double star systems, variable stars, clusters and 

 nebulee, &c., are described in their order of develop- 

 ment. The penultimate chapter, on stellar spectro- 

 scopy, occupies but twelve pages, reviewing briefly 

 the classifications of Secchi, Vogel, Pickering, 

 Lockycr, and Huggins. A curious statement is that 

 the star Sirius has but little atmosphere, as indicated 

 bv its thick hydrogen lines and thin metallic lines. 

 Surely the opposite is the case ; for the hydrogen 

 absorption lines to be so wide requires a very exten- 

 sive atmosphere, at the base of which there must be 

 a very considerable gravitational pressure. Little 

 mention is made of the enormous progress made 

 during recent years by the investigations of " enhanced 

 lines " in stellar classification, although this is now 



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