devoured the pastures of the wilderness," Joel i. 10-12, 18, 20.

4. Snow.-Snow consists of such vapours as are frozen while the particles are small. It differs from hail and hoar-frost, in being crystallized, which they are not. When a flake of snow is examined by a magnifying-glass, 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. Many of the flakes of snow are of a regular figure, for the most part stars of six points, and are as perfect and transparent ice as any we see on a pond or river. Their forms present an almost endless variety, are often very regular and beautiful, and reflect, with exceeding splendour, the rays of the sun. When they are very large, they are said to indicate the approach of thunder. The different forms which the flakes of snow exhibit, when viewed through microscopes, are represented in figure 6. These crystals of snow are from one-third to one thirty-fifth of an inch in diameter, in their natural size. Experiments have been made, which prove that snow is twenty-four times lighter than water, and that it fills up ten or twelve times more space at the moment of falling, than the water produced from it, when melted. It is worthy of remark, that previous to the fall of snow, and during its

continuance, the temperature continues at about The lightness of snow, although it is

32o.

Fig. 6.

firm ice, is owing to the excess of its surface in comparison to the matter contained under it. Its whiteness is owing to the small particles into which it is divided; for ice, when pounded, will become equally white.

Snow is frequently formed in the lower regions of the atmosphere. A very cold stream of air admitted into a room in which the

contained air is much warmer, and loaded with watery particles, will occasion its formation. In the huts of those who inhabit the arctic regions, snow is frequently formed in this manner. Dr. Robertson states that, in a crowded assembly-room in St. Petersburg, a stream of cold air was accidentally admitted into the room by a gentleman breaking a pane of glass, on which the vapour in the air was immediately congealed, and fell in the form of snowflakes. In Siberia, Nova Zembla, and other northern regions, the same phenomenon frequently happens. Snow occurs in all regions of the globe at a certain height above the level of the sea, but it falls more abundantly on plains as we proceed from the equator to the poles. In the arctic regions, snow falls nine days out of ten in the months of April, May, and June, and often to a depth of two or three inches in an hour. Among the mountains of Germany, Italy, and Switzerland, snow is sometimes accumulated to such an extent as to produce the most terrific and destructive effects, as in the case of the rolling avalanche. An avalanche is a mountain-mass of ice, or frozen snow, which is sometimes loosened from its base, and descends from the mountains with a force so terrible, that it crushes the traveller beneath its power, and buries hamlets and villages in a common grave. In the year 1749, the whole village of Rucras, in the canton of Grisons, in Switzerland, was covered, and, at the same time, removed from its site, by an

avalanche of this description. But this change, which happened in the night-time, was effected without the least noise, so that the inhabitants were not aware of it; and, on awaking in the morning, could not imagine why daylight did not dawn. A hundred persons were dug out of the snow, sixty of whom were still alive, the interstices between the snow containing sufficient air to support life. Not many years ago, an instance occurred of a family buried under one of these avalanches, and who continued in that situation for above a fortnight, remaining all that time in utter darkness, and incrusted in a body of snow several hundred feet in thickness. A massy beam supported the roof against this enormous pressure; and a milch ass, that happened to be thus incarcerated with the people, furnished sufficient nourishment for the support of life, till they were, at length, restored to the light of day.

The great Dispenser of universal bounty has so ordered it, that snow is eminently subservient, as well as all his other works, to his benevolent designs. As the winter cold is much more hurtful to vegetables than to animals, the plants would perish, if their roots were not preserved by some covering. God has, therefore, ordained that the rain, which in summer cools and revives the plants, should, in winter, fall in the form of a soft wool to cover the vegetables, and to guard them from the inclemency of frosts and winds. It prevents the internal heat of the earth from escaping,

and forms a safe covering to the tender herb, till the winter cold has abated under the influence of the genial spring.

5. Hail.-Hail, which is a more compact mass of frozen water than snow, is formed by the congelation of vapour in the higher regions of the atmosphere. The drops of hail assume various figures, being sometimes round, at other times pyramidal, angular, thin, and flat, and sometimes stellated with six radii, like the small crystals of snow. When hailstones are broken open, or cut across, they are sometimes found within to be of a spongy structure; sometimes the interior presents a very beautiful radiated appearance, and not unfrequently exhibits regular and very remarkable concentric plates. They are often of considerable dimensions. They vary in size from that of a small seed, to that of a boy's marble; and, in some instances, they have been found as large as the eggs of a goose; the small generally falling in the more northerly climates, and on the tops of mountains, and the larger in France, Spain, Italy, and other countries, towards the south of Europe. Hailstones have fallen in Scotland, which have been proved to weigh five ounces. In North America, they have sometimes been picked up weighing fifteen ounces; and, on October 5th, 1831, one fell at Constantinople which weighed more than a pound! The average velocity with which they fall, has been estimated at seventy feet per second, or at the rate of fifty miles an hour; and conse