SNOW, a well-known meteor, formed by the freezing of the vapours in the atmosphere. It differs from hail and hoar-frost in being as it were crystallized, which they are not. This appears on examination of a flake of snow by a magnifying glass; when the whole of it will appear to be composed of fine shining spicula diverging like rays from a centre. As the flakes fall down through the atmosphere, they are continually joined by more of these radiated spicula, and thus increase in bulk like the drops of rain or hailstones. Dr Grew, in a discourse of the nature of snow, observes, that many parts thereof are of a regular figure, for the most part so many little rowels or stars of six points, and are as perfect and transparent ice as any we see on a pond, &c. Upon each of these points are other collateral points, set at the same angles as the main points themselves: among which there are divers other irregular, which are chiefly broken points, and fragments of the regular ones. Others also, by various winds, seem to have been thawed, and froze again into irregular clusters; so that it seems as if the whole body of snow were an infinite
mass of icicles irregularly figured. That is, a cloud of vapours being gathered into drops, the said drops forthwith descend; upon which descent, meeting with a freezing air as they pass through a colder region, each drop is immediately frozen into an icicle, shooting itself forth into several points; but these still continuing their descent, and meeting with some intermitting gales of warmer air, or in their continual wastage to and fro touching upon each other, some of them are a little thawed, blunted, and again froze into clusters, or intangled so as to fall down in what we call flakes.
The lightness of snow, although it is firm ice, is owing to the excess of its surface, in comparison to the matter contained under it; as gold itself may be extended in surface, till it will ride upon the least breath of air.
According to Signor Beccaria, clouds of snow differ in nothing from clouds of rain, but in the circumstance of cold that freezes them. Both the regular diffusion of the snow, and the regularity of the structure of its parts (particularly some figures of snow or hail which fall about Turin, and which he calls rosette) show that clouds of snow are acted upon by some uniform cause like electricity; and he endeavours to show how electricity is capable of forming these figures. He was confirmed in his conjectures by observing, that his apparatus for observing the electricity of the atmosphere never failed to be electrified by snow as well as rain. Professor Winthrop sometimes found his apparatus electrified by snow when driven about by the wind though it had not been affected by it when the snow itself was falling. A more intense electricity, according to Beccaria, unites the particles of hail more closely than the more moderate electricity does those of snow, in the same manner as we see that the drops of rain which fall from thunder-clouds are larger than those which fall from others, though the former descend through a less space.
In the northern countries, the ground is covered with snow for several months; which proves exceedingly favourable for vegetation, by preserving the plants from those intense frosts which are common in such countries, and which would certainly destroy them. Bartholin ascribes great virtues to snow-water, but experience does not seem to warrant his assertions. Snow or ice-water is always deprived of its fixed air; and those nations who live among the Alps, and use it for their constant drink, are subject to affections of the throat, which are thought to be occasioned by it.
From some late experiments on the quantity of water yielded by snow, it appears that the latter gives only about one-tenth of its bulk.
Snow, in sea-affairs, is generally the largest of all two-masted vessels employed by Europeans, and the most convenient for navigation.
The sails and rigging on the main-mast and fore-mast of a snow are exactly similar to those on the same masts in a ship; only that there is a small mast behind the main-mast of the former, which carries a sail nearly resembling the mizen of a ship. The foot of this mast is fixed on a block of wood on the quarter-deck abast the main-mast; and the head of it is attached to the after-top of the main-top. The sail which is called the try-sail is extended from its mast towards the stern of the vessel.
Snowdon. When the sloops of war are rigged as snows, they are furnished with a horse, which answers the purpose of the try-sail mast, the fore-part of the sail being attached by rings to the said horse, in different places of its height.