Fig. 10. Fig. 11. Fig. 12.
Water freezes at an angle of 60°. On its first congelation, under favourable circumstances for observation, we perceive in parts, generally about the centre and around the margin, a corrugation of its surface. This corrugation presently discovers a series of distinct figures, needle-like in form, and analogous to the spiculæ of snow. As the process continues, to each of these needles, while yet forming, a serrated incrustation of leafy or arborescent character is attaching itself, so that in time the greater number of them become each the centre of a crystalline pinna, not unlike a frond of the lady fern. [Fig. 25] ([page 140]) is a sketch of one, the size of the original, as observed by T. G. Rylands, Esq., of Warrington, and sent to us during the severe winter of 1855. The overlapping observable on one side of the pinna is a peculiarity generally to be found in three out of the six leaves forming the entire crystal.
Fig. 13. Fig. 14. Fig. 15.