5i8 REVIEWS 



tion is realized so far as the observational phases of the subject are con- 

 cerned. The special studies in this line cover a wide range and much 

 new matter is added to previous knowledge. In extending the treatment, 

 however, to generalizations and interpretations involving past work and 

 previous views, there appear some strange misconstructions. As these 

 take the form of statements leading up to new interpretations in such a 

 way as to form their background and basis, they require notice to forestall 

 confusion respecting the main subjects. For example, in the approach 

 to a new explanation of the growth of snow granules, the following state- 

 ment is made: 



In the Antarctic (as elsewhere), where a snow-drift or other mass of snow 

 crystals persists for a certain time, a change occurs in the size and shape of the 

 individual crystals, this change (at least within certain limits) being progres- 

 sively toward an increase in the mean size of the crystal. Broadly speaking, 

 this modification probably takes place by the elimination of those crytsals which 



are of least size, and by the addition of their mass to the larger crystals 



This dependence of the rate of change upon the temperature is supported by 

 laboratory experiments,* and from laboratory experiments we also know, at 

 least for temperatures slightly below freezing point, that the rate of the change 

 increases with the pressure applied, f These two facts have given rise to the 

 theory that the growth of certain crystals at the expense of others takes place 

 only when the snow or ice is close to the melting temperature [pp. 45-6]. 



This last statement has the force of an intimation that the growth of 

 snow crystals much below the melting point was not a factor of previous 

 views and that these left an unoccupied field to be exploited. But this 

 intimation is quite far from the truth. In the paper of Chamberlin, cited 

 as giving experimental evidence of granular growth, it is said (pp. 193-4) : 



The microscopic study of new-fallen snow reveals the mode of change from 



flakes to granules If measured systematically from day to day, the 



larger granules taken from beneath the surface of coarse-grained snow are found 

 to be growing. In a series of experiments to determine the law of growth, it 

 was found that when the temperature of the atmosphere was above the melting 

 point, the growth was appreciably more rapid than when the air was colder, 

 but that there was, on the average, an increase under all conditions of tempera- 

 ture. 



The italics are those of the paper cited, which was written twenty 

 years ago. The basal fact thus demonstrated and emphasized has been 



* T. C. Chamberlin, "A Contribution to the Theory of Glacial Motion," p. 193, 

 Decennial Publication. University of Chicago, 1904. 



fHess, Der Gletscher, p. 31 e/ seq. See also Appendix to the report. [Footnotes 

 the author's]. 



