January 19, 191 i] 



NATURE 



O'-D 



dvantage by advanced students of geology and 



_»ography, the educational section is of most use to 



different circle of readers. The author's criticisms 



t teachers and text-books would probably have been 

 Setter confined to a work expressly fcM" teachers, as it 



- not always good for the intellectual discipline of 

 -tudents to have their often scant}.- faith in their in- 

 >tructors still further reduced. Geographical educa- 

 tion should, moreover, proceed on such different lines 

 in countries in different stages of development, that 

 its discussion is of more local interest than that of 



hysical problems, which are of universal application. 



1 he educational essays should, however, be read by 



■.11 geographical teachers, who must benefit from their 

 high ideals and valuable practical suggestions. 



The fourteen physiographic essays in this volume 



how the development of Prof. Davis's views on 

 denudation. The earliest in date deals with the rivers 

 of Pennsylvania and New Jersey, and led to his well- 

 known classification of rivers according to their rela- 



ion to the original slope of the land. The wearing 

 away of the land to a plain sloping slowly to the sea 

 is brought out in two papers on the peneplain and on 

 base level, and they lead to the geographical cycle due 

 to the interaction between uplift and denudation. The 

 course of the geographical cycle in an arid climate is 

 discussed in a memoir first published by Prof. Davis 

 in 1905. .\mong the other papers included are those 

 on glacial erosion in France, Switzerland, and Nor- 

 way (1900), on the sculpture of mountains by glaciers 

 (1905), on the mountain ranges of the Great Basin, 

 and on the remarkable instances of river capture in 

 the valleys of the Seine, Meuse, and Moselle. 



The most striking feature in Prof. Davis's 

 get^raphical writings is his devotion to the 

 deductive method. He rejects emphatically the view- 

 that geography is to be advanced chiefly "by observa- 

 tion, description, and generalisation." To use those 

 methods only is, he says, to walk on one foot. He 

 claims that invention and deduction are as necessar}- 

 to geography as to any other science. Many of his 

 valuable results are due to his keen insight and not 



o his method, which cannot be unduly adopted with- 



ut altering the positicm of geography in the circle of 

 -ciences. The ver>- name geography implies that the 

 ■subject is descriptive rather than deductive, although 

 -<:)me deduction is required by all schools of 

 geographers. But it has hitherto been found con- 



enient to limit geographical work mainly to obser\-a- 

 tion, description, and generalisation, restricting ad- 

 vanced deductive methods to the special problem of 

 -geography — the relation of the earth to man. The 

 subject-matter of geography is so enwmous that it 

 seems reasonable as well as convenient that there 

 should be a special science and societies devoted to 

 the mapping and description of the earth as it is, 

 leaving its evolution and explanation to other sciences. 

 Geolc^y, on the other hand, is a " logos," not a 

 "graphe"! and henCe requires a more intimate 

 connection of observation and inference than does 

 physical geography. Much that Prof. Davis calls 

 geography has been generally regarded as geology. 



The distinction that has been so long established and 

 "las worked so well in this countr}-, is shown by Prof. 

 NO. 2 15 1, VOL. 85] 



Davis himself to have been accepted also in America; 

 for he is professor of geolog\' at Harvard and not 

 of geography. Most of his physiographic essays 

 are quite appropriate to a geological school, and they 

 have been more read in this countrv- by geologists 

 than by geographers. Four of them were published 

 in geological and six in geographical journals. 



Prof. Davis, however, regards geology- and 

 geography as essentially the same. "They are parts 

 of one great subject," he says (p. 196). " It is a mis- 

 fortune that we have no English word to include both 

 geography and geology " (p. 198). " To set them 

 apart " he describes as an " obsolescent system " 

 (p. 204). Prof. Davis, moreover, restricts geology to a 

 minor section of the joint subject ; he regards it fp. 37) 

 as the sequence of events in the earth's history, and he 

 regrets that such questions as rock weathering are not 

 included in geography. The geographer must, of 

 course, know some of the elementary facts of geology-, 

 as he does of meteorology and physics ; but he has so 

 many difficult problems connected with man on the 

 earth that he may conveniently refer the study of 

 complicated physical causes to astronomy, meteorology 

 and geology-. The abandonmenf of the conventional 

 boundary between geography and geology would 

 probably prove ultimately detrimental to both sciences. 



The classification of some of Prof. Davis's memoirs 

 as geology- instead of geography does not lessen their 

 high value. Probably no living writer has done so 

 much to improve the interpretation of denudation. 

 His deductive method and his keen insight have 

 enabled him in studying the history- of river systems 

 to unravel confused tangles of facts, and by skipping 

 intermediate phases to go back to stages of which 

 most geologists thought that no traces could be surely 

 recc^nised in existing geography. The two chapters 

 on glacial erosion illustrate the advantas^es and the 

 dangers of the deductive method; for according to 

 some geologists, it has led Prof. Davis to attach 

 undue weight to certain striking features of mountain 

 form, and to overlook features which must be in- 

 cluded in a complete explanation. Prof. Bonney's 

 j presidential address to the British Association has 

 brought the controversy on glacial erosicMi to a head. 

 It mav be hoped that the authoritative and masterly 

 statements on both sides will lead to an agreement 

 as to the main facts, but no settlement can be ex- 

 pected until the arguments of those who limit the 

 efficacy of glaciers as eroding agents have been 

 directly answered. J. W. G. 



TECHMCAL ORGAMC AXALYSIS. 

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THE original "Allen's Commercial Organic 

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