6 MR A. W. WATERS ON CERTAIN LINES 



chasms which have probably been excavated upwards, and 

 which, when uncovered, will present very much the ap- 

 pearance of Elden Hole. For example, the upper part of 

 the great chasm in the Speedwell Mine bears a strong re- 

 semblance to it, though there the process is not yet com- 

 plete; and could sections of the district south ofCastleton 

 be made, those hollow mountains would probably reveal 

 many such a cavity. 



IT, Certain Lines dbserved in Snow Crystals. 

 By Arthur W. Waters, F.G.S. 



Bead January 26th, 1875. 



The crystalline form of water belongs to the hexagonal 

 system ; and the best condition, but not the only one, for 

 observing this is presented by snow crystals, or, perhaps more 

 correctly, ice crystals; for with a very low temperature there 

 are frequently beautiful ice crystals floating in the air when 

 there is no snow-fall. 



Of such some snow is formed, but not all. Dr. Nettis, 

 of Middleburg, published some drawings in 1740; Scoresby 

 in 1822* figured about one hundred forms from the Arctic 

 regions; and Glaisher, in 1844, gave some very elaborate 

 drawings in the Journal of the Microscopical Society. The 

 figures from both these two last sources have been very 

 largely copied for various text-books and scientific works, 

 and are probably familiar to most present. 



These figures are made up of angular lines, which seems 



* Account of the Arctic Eegious. 



