NA TURE 



121 



THURSDAY, MARCH 31, 19 10. 



\ 



A FRENCH TREATISE ON PHYSICAL 

 GEOGRAPHY. 



Traite de Geographic physique: Climat, HydrO' 

 graphic. Relief du Sol, Bio gio graphic . By Prof. 

 Emmanuel de Martonne. Pp. viii + 910, and maps. 

 (Paris : Librairie Armand Colin.) Price 22 francs. 



EVERY writer of text-books is faced by the diffi- 

 culty that the science of which he treats 

 inosculates with and is overlapped by other branches 

 of science. One of his most important tasks, there- 

 fore, consists in the exercise of a wise judgment as 

 to what should be properly included, and what ex- 

 cluded, in the treatise he is preparing-. 



It has sometimes been suggested that all science 

 may be regarded a$ falling into the two divisions 

 geography and astronomy, the former dealing with 

 everything that relates to our own planet, the latter 

 with matters concerning the outside universe. But 

 however logical such a scheme of classification of the 

 sciences may be regarded, it cannot be commended 

 on the score of convenience. There is no branch of 

 physical or natural science which is not a part of 

 "earth-knowledge," but it would be clearly impossible 

 in a single treatise to deal with the foundations and 

 superstructures of physics, chemistry, geology, botanv, 

 zoolog}', and anthropology. A work on geography 

 must take for granted a certain amount of preliminarj^ 

 knowledge of science, and be contented with show- 

 ing their application to the explanation of the various 

 phenomena exhibited on the surface of the globe. 



In the preface to the work before us, its author sug- 

 gests as natural divisions of physical geography the 

 following : — Morphologie, I'hydrographie, le climat, 

 la biog^ographie, et la geographie humaine; and 

 the bulky volume now issued deals only with the first 

 four of these divisions. The author justly remarks 

 that it is almost impossible for any man to have a 

 complete personal knowledge of all these subjects, 

 but that specialisation becomes necessary ; he has 

 therefore sought and obtained assistance from various 

 colleagues and friends in dealing with different de- 

 partments of the subject. 



In the first division of the work, devoted to general 

 notions on the subject, a clear account, occupving 25 

 pages, is given o'f the history and evolution of geo- 

 logical science, and in this part, as in all following 

 divisions, a very useful and complete bibliography 

 of the subject is supplied. The question of pro- 

 jection is fully treated, and, for the very numerous 

 maps of the whole globe given throughout the work, 

 the conventional system of Molweide (or Babinet) is 

 adopted in preference to that of Mercator, thus avoid- 

 ing the extreme polar distortions of the latter system. 

 The 160 pages devoted to meteorology, and consti- 

 tuting the second division of the work, contains an ex- 

 cellent summary of that branch of science. The chief 

 meteorological instruments are described, and clear 

 statements given on the temperature, the hygroscopic 

 characters, and the movements of the atmosphere in 

 different areas ; and the bearings of these several 



NO. 2 log, VOL. S2A 



factors in producing different types of climate are 

 discussed with much skill. 



The subject of hydrography has more than 100 pages 

 devoted to it, and constitutes the third divi- 

 sion of the book. A good resume of the observations 

 made in recent years in the deep oceans is given with 

 abundant references, including those to the latest pub- 

 lished works. This is followed by chapters on the 

 movements of the oceanic water, on the lakes, and 

 on the rivers of the globe. 



The fourth part of the work, dealing with the forms 

 of the great land masses of the globe, constitutes the 

 largest division of the book, occupying no fewer than 

 340 pages. After a sketch of the methods employed in 

 surveying and of the different ways of representing 

 the results on maps, a list is given of the chief pub- 

 lished topographical maps of different parts of the 

 world. We notice here some singular omissions. 

 The Ordnance maps of England and Wales and of 

 Scotland, on the one-inch scale, are referred to, but 

 there is no mention of the existence of maps on 

 other scales, or of any of the Ordnance maps of Ire- 

 land ! The maps of the trigonometrical sur\-ey of 

 India are included, but no notice is taken of any 

 British colony, although Algeria and Tunis receive 

 full consideration. This is a matter which certainly 

 calls for rectification in a future edition. 



The forms of the land surfaces resulting from dif- 

 ferent kinds of erosion are dealt with somewhat fully 

 on the lines rendered familiar by the writings of Prof. 

 W. M. Davis. Under the title of palaeogeogrr.phy a 

 chapter is devoted to the forms and dimensions of land- 

 masses during former geological periods, and the some- 

 what problematical questions connected with the sub- 

 ject are dealt with in considerable detail. The map of 

 " Gondwanaland " on p. 587, in which the great con- 

 tinent of Permo-Carboniferous times is made to in- 

 clude, not only India and a large part of Africa, but to 

 extend over Australia and the western half of South 

 America, will naturally excite criticism from those who 

 believe in the permanance of ocean-basins ; as will also 

 the map of the world in Cenomanian times, in which, 

 following de Lapparent, Haug, and Freeh, the author 

 represents a northern and a southern Atlantis, and, 

 more doubtfully, a Pacific continent. The chapters on 

 glacial and desert conditions, and the surface features 

 resulting from them, are fully up to date, and con- 

 tain much useful information of a kind not usually 

 found in text-books. 



In the 180 pages devoted to " biogeography " there 

 is much useful information included, but opinions will 

 differ as to how far much of this matter should 

 legitimately form a part of a treatise on physical geo- 

 graphy. Such subjects as commensalism in plants 

 and animals, the fertilisation of plants, domestication 

 and its influence, mutation and saltation — important 

 as they undoubtedly are — seem scarcely to form a por- 

 tion of geographical science, and if they are included 

 it is difficult to understand why many similar ques- 

 tions are omitted. 



Apart from this difficult question of the limits which 

 the author should adopt for his subject, the work 

 before us is a mine of information, and especial praise 



