Atril 9, 1Q03] 



NA TURE 



J JO 



astronomical methods, having spent some ten years 

 exploring in tropical Africa, Egyptian deserts and in 

 the Andes of Chile and Argentina. The methods de- 

 scribed are sound and practical, and taking the book 

 as a whole, it will undoubtedly serve well as a course 

 of astronomical study for those explorers who can 

 afford time to read it. 



But the day of the explorer is nearly over, and it is 

 very desirable to substitute topographical for explor- 

 atory methods wherever possible. This is actually 

 being done at the present moment on the Gold Coast, 

 where Major Watherston is making a topographical 

 survey by means of long rigorous traverses controlled 

 by azimuths. In difficult countries where rapid tri- 

 angulation is impossible, this system should always 

 be adopted. As regards the perennial difficulty of the 

 initial longitude, it is not always realised that we have 

 now a series of well determined longitudes throughout \ 

 the whole length of Africa, that there has been a great j 

 increase in the number of telegraph lines in that | 

 continent, and that wireless telegraphy promises to be 

 of vast assistance in the determination of longitude 

 differences of quasi-geodetic accuracy. 



As this book is no doubt primarily intended for 

 German students, it is worth while noting that the 

 German colonial empire throughout the world has an 

 area of about one million square miles, and that the 

 largest single block of German territory is German 

 East Africa, with an area of less than 400,000 square 

 miles. It is in the long run cheaper to survey such 

 a country by topographical rather than by rough astro- 

 nomical methods, and the results are far more trust- 

 worthy, topographical work including the determin- 

 ation at wide intervals of zenith telescope latitudes 

 and telegraphic differences of longitude. It is believed 

 that the German authorities are fully alive to the im- 

 portance of these considerations, as may be inferred 

 from the excellent work of Captain Hermann and Dr. 

 Kohlschiitter in East Africa, and from the recent 

 boundary surveys in Togoland. 



The importance of purely astronomical exploration 

 diminishes yearly, and though it will be some time 

 before the astronomical explorer becomes extinct, the 

 scope of his usefulness grows continually less ; his last 

 home will perhaps be in Central Asia, in Brazil, or at 

 the Poles. Meanwhile, he will find Dr. Giissfeldt's 

 an excellent text-book in which to study elemen- 

 tary field astronomical methods, but he should only 

 employ these when topographical methods are im- 

 possible. C. F. Close. 



OUR BOOK SHELF. 



The Tutorial Physics. Vol. ii. Higher Text-hook of 

 Heat. By R. 'Wallace Stewart, D.Sc. Pp. viii + 

 396. (London : YV. B. Clive, 1903.) Price 6s. 6d. 

 This is a new and considerably enlarged edition of a 

 book which we have previously noticed (December 21, 

 1893). We then declared our belief in the writer as one 

 capable of stating with all clearness and necessary 

 accuracy the various laws, and of showing their prac- 

 tical application by means of appropriate examples. In 

 its present form, he appeals to a more advanced class 

 of student than hitherto; and the question arises 



NO. 1745, VOL. 67] 



whether the accuracy which was sufficient in an ele- 

 mentary statement is adequate in a more advanced ex- 

 position. With regard to the main part of the volume, 

 we answer in the affirmative. The author has evi- 

 dently been at great pains to secure lucidity and sim- 

 plicity without a sacrifice of precision; and we cordi- 

 ally recommend the book to those who are willing to 

 use it rightly. By this last phrase we mean to imply- 

 that it should be read to the accompaniment of pro- 

 longed work in the laboratory under the personal 

 guidance of an efficient teacher. Granted this accom- 

 paniment, we think the book will be very helpful to 

 those who are not taking physics as a principal subject 

 of study, and who therefore do not wish to be confused 

 by the bewildering detail and complication which larger 

 treatises supply. 



In a few places the above commendation must be 

 qualified. On p. 244, Dulong and Petit are stated 

 to have " found that for a given excess of temperature 

 the rate of cooling depended not only on the tempera- 

 ture of the body, but also on that of the enclosure." 

 That stumbling-block of expounders, the Joule-Thom- 

 son experiment, trips up the author repeatedly; though 

 we readily admit that he goes straight on the whole. 

 For example, on p. 272 it is declared to involve no 

 performance of external work; on p. 2S1 the amount 

 of external work done is expressed in the equation ; on 

 p. 382 the work is once more declared to be altogether 

 infernal. The first word on p. 2S3 should be increase, 

 not decrease. 



Vcrgleichende Anatomic der Wirbelthierc. Fiinfte, 

 vielfach umgearbeitete und stark vermehrte Auflage 

 des " Grundriss " der Vergl.-Anatomie der Wirbel- 

 thiere. Von Dr. Robert Wiedersheim. Pp. xix + 

 686. (Jena: Gustav Fischer, 1902.) Price 16 

 marks. 

 Although in the title of the present work the word 

 " Grundriss " is subordinated, the book is the fifth 

 edition of that originally so named. Its second edition 

 of 1888 replaced" the author's Lehrbuch (1882 and 

 1886), and its third, of 1S93, which formed the basis 

 of the second edition of an English translation, was 

 practically a new book. In this, certain modifications 

 were first introduced which have characterised all 

 subsequent editions, including the present one, in 

 which the method of treatment remains unchanged. 

 The most marked advance in the book under re- 

 view is the addition to eight of the nine sections of a 

 series of short resumes, which materially enhance the 

 value of the work, in the past a book of reference 

 only. 



In his preface the author enumerates fifteen sub- 

 jects which have been especially modified and extended, 

 chief among them the morphology of the head- 

 skeleton, as lately determined by Gaupp. There are 

 many minor curtailments and rearrangements in 

 various parts of the book, and the recognition of 

 the work of Milani and Hacker on the reptilian lung 

 and avian larynx, of Paulli on the nasal labyrinth, of 

 Budgett on the external gills of Gymnotus, of Oppel 

 on the alimentary viscera, of Strong on the metamor- 

 phosis of the cranial nerves, and Bles on the nori 

 abdominales, is sufficient to show that anatomists of 

 all nationalities have been duly recognised, and that 

 the book is up to date. 



There are in all 711 text-figures, grouped to form 

 379 sets, and there is still the single coloured plate, 

 designed to render clear the changes undergone by 

 the cranial nerves in the passage from the aquatic to 

 the terrestrial state. The bibliography, so largely the 

 secret of the popularity of past editions, now reaches 

 the appalling limit of" 120 pp. In using this record 



