We have thus far endeavoured to show the true bases of construction, and how that crystallization proceeds onwards from the simple forms to the more complex, and have selected from numerous varieties a few of the best types illustrative of this progress. Our limits will scarcely permit us further to individualise these beautiful creations; yet, not to mislead, it is necessary to refer to an intermediate order, in which the hexagon star is laden with divergent spiculæ between groups of prisms. [Fig. 36], selected from this very numerous class of figures, was one of several observed during the cold weather, following upon the general thaw, which terminated the long-continued and severe frost of 1855. The spiculæ were icicle-like, of the utmost delicacy, opaque, and well defined; the prisms, on the contrary, were watery, almost rounded, and, as it seemed, on the verge of dissolution. The entire figure had the appearance of two distinct orders of formation—the prisms which belong to a very low temperature, and the spiculæ which are commonly formed at and about the freezing-point. [Fig. 37] is another of the same class, and in a very intermediate state; the additions to the main radii are neither prisms nor spiculæ, yet partaking of the character of both: its peculiarity consists in the tertiary incrustations being placed downwards towards the centre. This form has been observed only during very severe cold.
[Fig. 38] is somewhat analogous to the crystals of water; its centre is hexagonal, but the prisms are irregular crystalline incrustations of the utmost delicacy and transparency; it was of large size, fully half an inch in diameter, and glistening like a fragment of talc among the snow-flakes, was discernible at a considerable distance.
Fig. 35.
[Fig. 39] ([page 156]) is a specimen of a double crystal; that is, two similar crystals united by an axis at right angles to the plane of each. It is highly complex, and the effect of each is more than doubled by the arrangement. Crystals so united are not unfrequent in severe weather.
During one winter our observations numbered nearly two hundred varieties.
Fig. 36.