REVIEWS 573 



against the valley walls and bottom, or against each other. This is 

 largely true even of the pebbles rolled on its bottom, as anyone may 

 see by examining the nick-marks that cover their surfaces and that 

 sharply distinguish them from glaciated pebbles, or by critically com- 

 paring a waterworked surface with a glacially worn surface. 



On the other hand a glacier does its work by virtue of its rigidity 

 and pressure, and scarcely at all by its momentum, for its velocity is 

 very low. A river with the same velocity as a glacier would be almost 

 absolutely inert as an abrading agency. In the judgment of the 

 reviewer no one is entitled in the present state of evidence to assume 

 that the laws of fluids control the action of glaciers except in external 

 similitude, which is due to the fact that gravitation is the dominant 

 factor in both cases. In convenient and popular exposition the simili- 

 tude has .many advantages, but in framing scientific doctrine and 

 nomenclature, and still more in mental procedure, it is attended by 

 danger. It is doubtless as important to avoid the similitude in critical 

 work as it is permissible to use it in easy exposition. 



__ T. C. C. 



Bartholomew's Physical Atlas: A?i Atlas of Meteorology. Vol. III. 

 A series of over four hundred maps. Prepared by J. G. 

 Bartholomew, F.R.S.E., and A. J. Herbertson, Ph.D., 

 and edited by Alexander Buchan, F.R.S. Under the 

 patronage of the Royal Geographical Society. Edinburgh, 

 1899. 



This is the first volume to appear of what promises to be an epoch 

 making work in scientific geography. The entire field of physical 

 geography is to be covered by seven volumes. The plan was furnisht 

 by the famous Physikalischer Atlas of Berghaus\ tho the field is vastly 

 extended, and it will make a work when completed, perhaps ten times 

 the size of the German atlas. 



This great venture is preparing under the direction of J. G. Bar- 

 tholomew, revised and edited by a corps of eminent specialists, in 

 volumes as follows : 



I. Geology — Sir Archibald Geikie. 

 II. Oceanography — Sir John Murray ; and 

 Orography — Professor James Geikie. 



III. Meteorology — Alexander Buchan, 



IV. Botany — Professor Bayley Balfour. 



