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AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. XXXII. — Experimental Studies and Observations on 

 ■ Ice Structure ; by O. D. von Engeln. 



Introductory. — A detailed account of these experiments has 

 been published nnder the joint authorship of the late R. S. 

 Tarr and the present writer in the Zeitschrift fur Gletscher- 

 kunde (1915, vol. ix, pp. 81-139). In view of the restrictions 

 imposed by the European situation, the fact that the Zeitschrift 

 reaches only glacialists and that new points have come up 

 since the writing of the longer article, it is deemed worth 

 while to summarize the chief results obtained in an American 

 periodical. Those specially interested in the subject are, how- 

 ever, referred to the fuller statement which contains the 

 records, data, and methods followed in individual experiments, 

 references to earlier literature, and acknowledgment to those 

 who gave assistance in various ways. 



The initiative in developing the work and some of the 

 tentative conclusions are to be credited to the late Prof. R. S. 

 Tarr. The experiments furthermore comprise the continuation 

 of the investigations begun by Professor Tarr in the winter of 

 1910-11. The earlier results were published under the title 

 " The Properties of Ice — Experimental Studies," by R. S. 

 Tarr and J. L. Rich.* The experiments herein described 

 were performed in the winter of 1911-12, when better 

 facilities and apparatus were available. 



Record of the Experiments. — The experiments were planned 

 primarily to secure data bearing on the structure and flow of 

 glacial ice. In the main they consisted of compression tests 

 (a) on cubes of ice unsupported at the sides and (b) on cylinders 

 of ice enclosed in metal cases of varying degrees of resistance 

 up to complete rigidity under the pressures applied. The 



* Zeitschrift fur Gletscherkunde, vi, pp. 225-249, 1912. 



Am. Jour. Sci. — Fourth Series, Vol. XL, No. 239. — November, 1915. 

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