observed, on the first of April, 1815, a great number of snow-balls scattered over the fields, varying from one to fifteen inches in diameter. They had evidently been caused by the wind rolling up the snow, as the track of the balls was distinctly visible. In 1830, similar balls were seen by Mr. Sheriff, in East Lothian, scattered over a wide extent; some of the masses being eighteen inches in diameter.

285. But the most remarkable exhibition of this kind was beheld by Mr. Clarke, of Morris county, New Jersey, in January, 1808. A crust having formed upon the snow that had previously fallen, a light snow soon after occurred, covering the glassy surface to the depth of three-quarters of an inch; the sky then suddenly became serene, and a high wind arose. Beneath the force of the gale, small portions of snow would slide along for the distance of ten or twelve inches, when they would begin to revolve, rapidly increasing both in length and diameter. Where the descent of the ground favored their formation, masses rolled up to the size of a barrel, and, as far as the eye could see, the dazzling surface was covered with balls and cylinders of snow; varying in magnitude from ten inches to three feet in diameter. Upon examination they were found to be hollow at each end, almost to the centre, and as round as if they had been so many logs of wood turned in a lathe. The cylinders covered nearly 400 acres, and their number was judged to be nearly 40,000.

286. RED SNOW. In 1819, Capt. Ross beheld snow of a brilliant crimson hue, clothing the sides of the mountains at Baffin's Bay; rising, according to his report, to the height of several hundred feet, and extending to the distance of eight miles.

Snow of this tint is not, however, confined to the Arctic regions. Raymond had previously observed it in the Pyrenees. In 1818, vast masses were spread over the Italian Alps and Apennines, and five years before

Relate the several accounts of natural snow balls.
What is said of red snow?

the whole range of the last-mentioned chain was covered with rose-colored snow. The same phenomenon was seen by Scoresby, Parry and Franklin, in high northern latitudes, and the navigators of the southern hemisphere have found red snow in great quantities at New Shetland, 62° S. Lat.

287. In snows of great depth, the accounts differ in regard to the thickness of the colored stratum. Ross conjectured, that, in the Arctic mountains, the crimson hue penetrated to the depth of several feet below the surface; while others could not detect its existence beyond one or two inches.

Among the Alps, the red snow is usually discovered in little sheltered hollows, in layers not exceeding twc or three inches in thickness: though these are sometimes situated far beneath the general surface of the

snow.

288. GREEN SNOW. When the French meteorologists, Martin and Bravais, traversed a field of snow at Spitzbergen, in 1838, it appeared of a green hue, wherever it was pressed by the foot. The coloring matter seemed to reside just below the surface, which was brilliantly white.

Upon another excursion, the first observer beheld the green particles spread like dust over the snow, which was also tinted green beneath the surface, and upon the sides of the field.

289. CAUSE. These singular hues are produced by the presence of an infinite number of a certain class of microscopic plants, which from their great tenacity of life, are capable, not only of existing at a very low temperature, but even of flourishing with extraordinary vigor.

These minute vegetable forms are composed of globules, which vary in diameter from one-thousandth of an inch to one three-thousandth. Each globule is divided into seven or eight cells, filled with a liquid, in which

What of green snow?

To what cause are those colors attributed ?

live a great n imber of animalcules. The cells are generally red, which is supposed to be their original color, the green tint being probably acquired by exposure to the air and light.

These extraordinary hues may, therefore, be regarded as originating in the same plant, in different stages of development.

290. USES OF SNOW. Snow subserves many important purposes. Gathered in exhaustless stores upon the high mountains of the globe, it feeds, as it gradually melts beneath the heat of summer, thousands of rivers, which, flowing on from clime to clime, enrich the soil and crown the land with plenty.

The snow-capped mountains are the natural refrigerators of the glowing regions that lie within the tropics; cooling the winds that pass over them, and mitigating the fierce temperature of the atmosphere.

In the higher latitudes, where the winters are severe, the snow forms a warm covering for the soil, and defends vegetation from the rigors of the frost. It is well known, that grain, during an open winter, is frequently destroyed by the cold; and, in the mild climate of England, Alpine plants have perished, in consequence of being deprived of their natural covering of snow.

During the long night of the polar climes, the intensity of the darkness is diminished by the presence of the snow; inasmuch as it reflects, instead of absorbing, like the bare ground, the faint light that there proceeds from the sky. Nor is it to be forgotten, that, in these inclement regions, the wretched natives would be unsheltered during the winter, were it not for the snow; since this, when cut into blocks, supplies the Esquimaux with the means of constructing their huts.

What is said in regard to the uses of snow? 6

CHAPTER VI.

OF HAIL.

291. HAIL. The ice that descends in showers, and usually in summer, is called hail. It is different from sleet, which is nothing more than frozen rain, and occurs only in cold weather.

292. STRUCTURE. Hailstones are generally pearshaped, and if they are divided through the centre, they are found to be composed of alternate layers of ice and snow, around a white, snowy nucleus, resembling the coats of an onion. The surface is rough, and is some

times studded with icicles.

293. SIZE. Hail varies in size, from stones as small as a pea to those which are several inches in circumference. Benvenuto Cellini relates in his memoirs, that during his journey from Italy to France, he was overtaken by a terrible storm in the vicinity of Lyons; hailstones falling of the size of lemons, and with sufficient force to kill even men and cattle.

At Roncesvalles, in August, 1813, there fell upon a division of the British army a storm of hail, in which the stones ranged in size from a bean to a hen's egg. The tin camp-kettles of the soldiers were indented by the masses of ice, some of which were round, and armed with icicles three inches in length.

In May, 1847, hailstones of immense size descended near the town of McDonough, in Georgia; one of them was measured an hour after it fell and found to be ten inches in circumference. During a terrific storm, that occurred at Cazorta, in Spain, on the 13th of June, 1829, the roofs of the houses were broken in by the hail. Some of the stones are stated to have weighed nearly four pounds and a half. It is probable that such extra

Define hail.

What is the form and structure of the hailstone?

What is said of its size?

Narrate the facts stated.

ordinary masses as those which have been mentioned, are formed by the union of several hailstones frozen together.

GEOGRAPHICAL DISTRIBUTION.

294. Hailstones are most frequent in the temperate climes, and rarely occur within the tropics, except in the vicinity of mountains whose summits tower above the limit of perpetual frost. Although by no means common, they are not unknown in the high northern latitudes. Simpson, on the 12th of August, 1839, was exposed in the straits of Boothia, in 68° 32′ N. Lat., to a tremendous thunder-storm, accompanied with torrents of rain and heavy showers of hail.

It is mostly in summer, and usually at the hottest part of the day, that hail is observed to fall. Scarcely any occurs in the night.

ORIGIN.

295. The structure of the hailstone shows that it is not formed at once; for the concentric layers around the snowy nucleus, consist of different accessions of moisture, successively condensed and congealed upon the surface of the stone.

The light, porous texture of the snowy centre, seems to indicate, that the place of origin must be some region in the atmosphere where the air is rare, and the cold intense; since the appearance of the centre is similar to that presented by a drop of water, when frozen under the exhausted receiver of an air-pump.

296. It is necessary then for the production of hail, that a warm, humid body of air should mingle with another so extremely cold, that their temperature, after uniting, shall be below the freezing point. This combination must also take place during the warmest period

Where do hailstorms frequently occur?

Where rarely?

When do they usually prevail?

What indicates that the hailstone is not formed at once?
Where must it originate?

What conditions are necessary for the production of hail?