162 POPULAR SCIENCE MONTHLY. 



been exactly what it was. . . . Many highly valuable compendia 

 of Physical Geography, for the use of scientific students of that sub- 

 ject, are extant; but in my judgment most of the elementary works I 

 have seen begin at the wrong end, and too often terminate in an 

 ominum gatherum of scraps of all sorts of undigested and unconnected 

 information; thereby entirely destroying the educational value of that 

 study which Kant justly termed the 'propaedeutic- of natural knowl- 

 edge.' " (Preface to 'Physiography,' 1878). 



Here we find clear recognition of the need of introducing a consid- 

 eration of causes, just as was urged by Guyot; and furthermore a 

 recognition of the need of linking together in their natural relations all 

 the items which together constitute the content of the subject. It 

 may, however, be contended that the attempt to combine in a single 

 course of study the elementary principles of chemistry and physics, of 

 geology and astronomy, along with those of physical geography, is not 

 practicable from an educational point of view; such a combination will 

 not secure either the clear knowledge or the strong discipline that can 

 be derived from systematic courses in two or three of these subjects, 

 presented separately. Text-books like Hinman's 'Eclectic Physical 

 Geography' and Mill's 'Eealm of Nature,' in both of which a broad 

 range of other than geographical subjects is covered, do not seem to-day 

 to be in so much favor as those books which attend more closely to the 

 true content of our subject. Indeed, with respect to physical geog- 

 raphy, considered from the scientific and educational point of view, a 

 report on College Entrance Eequirements, recently published by our 

 National Educational Association,* presents the best definition and out- 

 line of the subject that has yet appeared. It advises the omission of 

 irrelevant matter, however interesting such matter may be in itself. 

 The principles of physics and the succession of geological formations 

 with their fossils, the classification and distribution of plants and 

 animals must be taught elsewhere; but much profit may be had from 

 terrestrial phenomena by which the principles of physics are illustrated, 

 and from the consequences of past geological changes in determining 

 present geographical conditions, and especially from the physiographic 

 controls by which the distribution of organic forms is determined. 



The general scheme under which all land forms may receive ex- 

 planatory description must consider chiefly the movement and erosion 

 of the earth's crust. Deformation offers a part of the earth's crust 

 to be worked upon. Various destructive processes of erosion work 

 upon the offered mass, and the streams, with their transported waste, 

 follow the depressions in the carved surface. So important is the ele- 

 ment of erosion, and so leading is the part played by rivers in erosive 



* Proceedings, 1899, 780-792 ; also in the Journal of School Geography, September, 189S. 



