94 



NATURE 



{Dec. 5, 1S78 



improvement in the rendering into English of the matter 

 already employed. In the direction of chemico-botanical 

 research there is great room for investigation, and a 

 text-book embracing the knowledge already acquired, and 

 information on points in connection with the chemistry 

 of vegetable physiology, would render such a work of 

 interest not only to the scientific chemist or botanist, 

 but also to the general reader. Baron von Mueller's 

 translation forms an excellent nucleus for such a work, 

 and should a future edition of the book be required, we 

 should hope to find it enlarged in such directions. 



J. M. T. 



GEOGRAPHICAL ASTRONOMY 



A bliss der praktischen Astronojnie, vorziigUch in ihrer 

 Anwendmig mtf geographische Ortsbestimiming. Von 

 Dr. A. Sawitsch, nach der zweiten russischen Original- 

 Ausgabe. Neu herausgegeben von Dr. C. F. W. 

 Peters. (Leipzig, 1S79.) 



AS may be inferred from the" title of this work, the 

 astronomical reader will not find it to be a general 

 itreatise on the practical branches of the science, but one 

 • confined to the theory and uses of instruments, and 

 explanation of methods employed at the present day in 

 the determinations of geographical positions. As such 

 . the name of its author. Dr. A. Sawitsch, the well-known 

 Professor of Astronomy in the Imperial University of St. 

 Petersburg, will give the work high recommendation in 

 the estimation of the student. The two volumes of the 

 original edition are now incorporated in one, and such 

 modifications as have been rendered necessary by the 

 introduction of new or improved forms of instruments, and 

 refinements of observation and reduction have been 

 introduced in a great measure by the author himself. 

 In the opening chapter we have explanations of the 

 \'ariou3 methods of reckoning time, and the transforma- 

 tion of one into another; the reduction of mean into 

 apparent places, the calculation of refraction and parallax, 

 and the influence of the earth's compression upon the 

 geocentric co-ordinates of points upon the surface, with 

 .remarks upon angular measures in general, and upon the 

 astronomical telescope and its adjustment, the micro- 

 scopes, verniers, level, &c. In the first section, the 

 author treats of the transit instrument, and enters into 

 the various adjustments to which it is subjected, and also 

 describes in some detail the universal instrument of 

 Piston and Martins, and the errors of division to which 

 instruments for angular measures may be liable. The 

 second section is devoted to the determination of 

 latitude and time by measure of zenith distance, of time 

 from corresponding altitudes, &c. The third section enters 

 more fully into the uses and theory of the transit instru- 

 ment, and likewise describes Bessel's method for the 

 determination of latitude thereby, supplying practical 

 rules and an example. The next section treats of the 

 determination of azimuth, and of the influence of diurnal 

 aberration on the polar co-ordinates of a star. The fifth 

 section contains a valuable outline of the various methods 

 applicable to the determination of terrestrial longitude, 

 including the telegraphic method, the transportation of 

 chronometers, and longitude by observations of eclipses, 

 especially those of the sun, and by lunar occultations. 



The reference to the utility of echpses for longitude- 

 determination leads to an important chapter on Hansen's 

 method for the calculation of the general circumstances 

 of these phenomena upon the earth's surface, and the 

 methods followed by Dr. Zech, in his researches on the 

 historical eclipses ; and, as a numerical example, the 

 formulae are applied to the computation of the circum- 

 stances of the total solar eclipse of August 18, 1887, to 

 which frequent reference has been made in astronomical 

 treatises. The data are founded upon the lunar tables of 

 Hansen and the solar tables of Leverrier. Further, we 

 have a discussion on moon-culminators in their applica- 

 tion to longitudes, with notices on the methods of Nicolai 

 and Struve, and a fuUy-worked-out example. The sixth 

 section relates to the reduction of the longitude, latitude, 

 and azimuth of a place to another, both accurately and 

 approximately, and the determination of the distance of 

 points on the terrestrial spheroid, of which the geo- 

 graphical positions are given. There are two supple- 

 mentary chapters : the one bearing upon reflection- 

 instruments, and of course entering at length into the 

 use of the sextant ; the other treating of interpolation, 

 with special reference to the formulae of Bessel and 

 Hansen. 



In the language in which this work originally appeared 

 it would be almost a sealed book in Western Europe. 

 The excellent translation into a language of which every 

 scientific student should, in these days, possess a know- 

 ledge, now placed in our hands by Dr. Peters, will be, 

 without doubt, a welcome addition to his means of in- 

 struction on an important branch of practical astronomy. 



OUR BOOK SHELF 



A Treatise on Dynatnics of a Particle, with numerous 

 Examples. By P. G. Tait and the late W. J. Steele. 

 Fourth Edition. (London : Macmillan and Co., 1878.) 



The bibliography of this revised text-book is — a first 

 edition in 1856, 304 pages; a second edition in 1865, 363 

 pages ; a third edition in 187 1, 428 pages ; and the present 

 edition of 407 pages. There are slight alterations in the 

 disposition and amount of the matter in this edition, 

 caps. x. and xi. of the third are put into cap. ix., caps. v. 

 and vi. are contained in cap. v. of the fourth. The 

 position of some of the exercises has been changed. 

 The main features remain unaltered. The revision has 

 had the advantage of Prof. Greenhill's supervision, who 

 has verified (and corrected where necessary) the Examples 

 and has freely introduced the use of Elliptic Functions. 

 There is no need of any commendation for a text-book 

 so well-known. We are, however, very much disposed 

 to think that had Prof. Tait composed the work at a later 

 date than he did, it would have differed somewhat from 

 its present form and have approximated more closely to 

 the Natural Philosophy brought out under the joint editor- 

 ship of Sir William Thomson and himself. The author 

 justly complains that " several sections in which some 

 novelties appear have been translated almost letter for 

 letter and transferred, without the slightest allusion to 

 their source, to the pages of a German work. Several 

 other books have obviously been similarly treated. It is 

 well that this should be known, as the English authors 

 might otherwise come to be supposed to have adopted 

 these passages siinpliciter from the German." 



Familiar Wild Flowers. Figured and Described by 

 F. Edward Hulme, F.L.S., F.S.A. First Series. With 

 Coloured Plates. (Cassell, Petter, and Galpin.) 



Scientific books are of three kinds : to inform the 



