WOLFF. — SNOW CRYSTALS. 431 



EXHIBITION AND PRELIMINARY ACCOUNT OF A COL- 

 LECTION OF MICROPHOTOGRAPHS OF SNOW 

 CRYSTALS, MADE BY W. A. BENTLEY. 



By J. E. Wolff. 



Presented April 13, 1898. 



The study of snow crystals dates back to the middle of the sixteenth 

 century, when the first drawings appeared in the book of Olaus Magnus 

 in 1555, and other early authors, including Des Cartes and Keppler, 

 have described and figured these forms. In 1820, William Scoresby 

 published 96 drawings of snow crystals made in the Arctic regions, 

 in 1855 J. Glaisher 150, and in the same year Franke 119. 



The first reproduction of microphotographs of snow crystals was 

 in the small monograph of G. Hellmann in 1893 with about 60 

 examples,* and in the same year G. Nordenskiold published about the 

 same number, t In 1894 Hellmann published a plate of much larger 

 pictures taken by a Russian photographer. | 



The present collection has been made by Mr. W. A. Bentley of Nash- 

 ville, Vermont, during the last twenty years, and includes about 400 of the 

 most interesting examples out of a total of 550 made by him. Through 

 the disinterestedness of Mr. Bentley the collection has been acquired 

 at a nominal cost for the Harvard Mineralogical Museum for study and 

 public exhibition. 



Its scientific value is enhanced by his notes, which comprise a number 

 of meteorological observations made by himself at the time many of the 



* Sclineekrystalle-Beobachtungen und Studien, by Professor G. Hellmann, 

 with eleven cuts and eight heliogravures after the micro-photographs of R. 

 Neuhauss, M. D. Berlin, Rudolph Muckenberger. The historical summary given 

 above is taken from this work. 



t Preliminary Communication concerning an Investigation of Snow Crystals. 

 Geol. Foren. i Stockholm. Forh. Bd. 15, pp. 146-158. 1893. English summary in 

 Nature, Vol. XLVIII. pp. 592-594. 



t Meteorologische Zeitschrift, 1894, p. 281. 



