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ON COLUMNAR GROUND ICE. 

 By T. ALGERNON CHArMAN, Esq., M.D., Abergavenny. 



There is a remarkable form of ice found on the surface of the- ground, 

 which I have often noticed, and on which I last winter made some observations 

 with the object of determining the causes of its peculiar structure. 



The peculiarity of this ice that is most likely to attract attention is that 

 it is formed where there is apparently no water, or at least that a considerable 

 mass of transparent ice is formed on the surface of the earth in places that are 

 often dry, and even in winter, though the ground may be very wet, there is 

 practically no water separable from the earth which it saturates. Its most 

 distinctive character, however, is the beautiful columnar forms it assumes — from 

 simple pillars and groups of pillars, to arches, colonades, and labrinthine 

 masses. 



The only paper on the subject I can find is one " On Columnar 

 Crystallization of Ground Ice," in the Edinburgh New Philosophical Journal 

 for 1850, by the Rev. Dr. Scoresby, whose name is so well known in connection 

 with arctic exploration. He describes and figures numerous forms of this variety 

 of ice, but offers no observations bearing on its mode of formation, and hardly 

 offers any theory except the suggestion that the electric condition of the earth 

 and air are the determining causes of its peculiar structure. 



Recently there have been several short notes on the subject in " Nature," 

 but the Columnar form of ice is apparently confounded by several writers with 

 Prismatic Ice. The form of ice to which I think the term prismatic should be 

 restricted occurs when a mass of ice formed or resting on the surface of the 

 ground is slowly melting at a temperature very close to 32° ; at least these are 

 the conditions under which I have met with it, and it has been described as 

 so occurring. Under these conditions the ice forms itself into a number of 

 portions easily separated from each other, but fitting accurately together so 

 as to preserve the Outlines of the original mass of ice. Each of the pieces is of 

 irregular prismatic shape, with flat sides and tolerably sharp angles, varying in 

 size up to half an inch in length or even much longer, and with differing 

 numbers of sides (usually 5 or 6), and variously angled ends, in short irregular 

 prisms and in no sense crystals, nor do they appear to have any relation to the 

 crystalline structure of the ice, excepting that the axes of the prisms are 

 perpendicular to the original surface of the ice. The structure depends 

 probably on causes similar to those that lead to the prismatic structure in 

 basalt, i.e., to contraction from a change of temperature, in the present instance 

 not on a depression but on an elevation of temperature. 



