Prismatic Structure in Ice

Abstract

OF late years attention has not unfrequently been called to this singular structure in ice, of which a number of instances are collected by the Rev. G. F. Browne, in his valuable book on the “Ice Caves of France and Switzerland” (chap, xviii.) In August, 1865, I had the opportunity of examining in his company some of these curious caverns; and since then have been on the look out for other instances of this structure. In January, 1867, I found it very well exhibited on a pond in Cambridge, an account of which may be found in the Proceedings of the Cambridge Philosophical Society, Part IV. and (more briefly) in my “Alpine Regions,” pp. 94, 334. I again saw it last summer in a block of river or lake ice, which was brought on board a steamer at Christiansand (Norway) from an ice house. This block was about 8 inches thick. The prisms were rather irregular in form, the area of their ends varying from about a quarter of a square inch to one square inch, the sides being usually five or six in number. The prisms were at right angles to the planes of freezing, which were well marked.