their mutual collision. This generally happens early in the month of June; and a few weeks are commonly sufficient to disperse and dissolve the floating ice. The sea is at last open, for a short and dubious interval, to the pursuits of the adventurous mariner.

While icebergs are thus the slow growth of ages, the fields or shoals of saline ice are annually formed and destroyed. The ice generated from melted snow is hard, pellucid, and often swells to enormous height and dimensions. But the concretion of salt water wants solidity, clearness, and strength, and never rises to any considerable thickness. It seldom floats during more than part of the year; though, in some cold season, the scattered fragments may be surprised by the early frost, and preserved till the following summer.

The whale-fishers enumerate several varieties of the saltwater ice. A very wide expanse of it they call a field, and one of smaller dimensions a floe. When a field is dissevered by a subaqueous or grown swell, it breaks into numerous pieces, seldom exceeding forty or fifty yards in diameter, which, taken collectively, are termed a pack. This pack again, when of a broad shape, is called a patch; and, when much elongated, a stream. The packs of ice are crowded and heaped together by violent winds; but they again separate and spread asunder in calm weather. If a ship can sail freely through the floating pieces of ice, it is called drift-ice; and the ice itself is said to loose or open. When, from the effect of abrasion, the larger blocks of ice are crumbled into minute fragments, this collection is called brash-ice. A portion of ice rising above the common level is termed a hummock, being produced by the squeezing of one piece over another. These hummocks or protuberances break the uniform surface of the ice, and give it a most diversified and fantastic appearance. They are numerous in the heavy packs, and along the edges of ice-fields, reaching to the height of thirty feet. The term sludge is applied by the sailors to the soft and incoherent crys tals which the frost forms when it first attacks the ruffled surface of the ocean. As these increase, they have some effect, like oil, to still the secondary waves; but they are prevented from coalescing into a continuous sheet, by the agitation which still prevails; and they form small discs, rounded by continual attrition, aud scarcely three inches in diameter, cal. led pan-cakes. Sometimes these again unite into circular pie. ces perhaps a foot thick, and many yards in circumference. The fields and other collections of floating ice are often

discovered at a great distance, by that singular appearance on the verge of the horizon, which the Dutch seamen have termed ice-blink. It is a stratum of lucid whiteness, occasion. ed evidently by the glare of light reflected obliquely from the surface of the ice against the opposite atmosphere. This shining streak, which looks always brightest in clear weather, indicates to the experienced navigator, twenty or thirty miles beyond the limits of direct vision, not only the extent and fig. ure, but even the quality of the ice. The blink from packs of ice appears of a pure white, while that which is occasion. ed by snow-fields has some tinge of yellow.

The mountains of hard and perfect ice are the gradual production, perhaps, of many centuries. Along the western coast of Greenland, prolonged into Davis's Strait, they form an immense rampart, which presents to the mariner a sublime spectacle, resembling, at a distance, whole groups of churches, mantling castles, or fleets under full sail. Every year, but especially in hot seasons, they are partially detached from their seats, and whelmed into the deep sea. In Davis's Strait those icebergs appear the most frequent and about Disco Bay, where the soundings exceed 300 fathoms, masses of such enormous dimensions are met with, that the Dutch seamen compare them to cities, and often bestow on them the familiar names of Amsterdam and Haerlem. They are carried toward the Atlantic by the current which generally flows from the north-east, and after they reach the warmer water of the lower latitudes they readily dissolve, and finally disappear, probably in the space of a few months.

The blocks of fresh-water ice appear black as they float; but show a fine emerald or beryl hue when brought up on the deck. Though perfectly transparent like crystal, they some. times enclose threads or streamlets of air-bubbles, extricated in the act of congelation. This pure ice, being only a fif teenth part lighter than fresh water, must consequently project about one-tenth as it swims on the sea. An iceberg of 2000 feet in height would therefore, after it floated, still rise 200 above the surface of the water. Such, perhaps, may be considered as nearly the extreme dimensions. Those mountains of ice may even acquire more elevation at a distance from land, both from the snow which falls on them, and from the copious vapors which precipitate and congeal on their sur face. But in general they are carried forward by the cur. rent which sets from the north-east into the Atlantic, where, bathed in warmer fluid, they rapidly waste and dissolve. It

may be shown by experiment, that if the water in which they float had only the temperature of 42 deg., the mass of ice would lose the thickness of an inch every hour, or two feet in a day. Supposing the surface of the sea to be at 52 deg., the daily diminution of thickness would be doubled, and would therefore amount to four feet. An iceberg having 600 feet of total elevation would hence, on this probable estimate, require 150 days for its dissolution. But the melting of the ice would be greatly accelerated if the mass were impelled through the water by the action of winds. A velocity of only a mile in an hour would triple the ordinary effect. Hence, though large bodies of ice are often found near the banks of Newfoundland, they seldom advance farther, or pass beyond the 48th degree of latitude. Within the Arctic regions those stupendous blocks remain, by their mere inertia, so fixed on the water, as commonly to serve for the mooring of vessels employed in the whale-fishery. In some cases, however, it is a necessary precaution to lengthen the cables, and ride at some distance from the frozen cliffs; because the fragments of ice, which the seamen term calves, are frequently detached from the under part of the mass, and, darting upwards, acquire such a velocity in their ascent, that they would infallibly strike holes into the ship's bottom.

The ice produced from salt water is whitish, porous, and almost opaque. It is so dense, from the quantity of strong brine enclosed in its substance, that, when floating in the sea, it projects only one-fiftieth part above the surface. The porous saline ice has a variable thickness, yet seldom exceeding six feet. But this same ice which, during the greater part of the year covers the Arctic seas, is annually formed and destroyed; a small portion of it only, and at certain seasons, escaping the general wreck. The thaw commonly lasts about three months; and during that time the heat of the solar rays, which, though oblique, yet act with unceasing energy, whe ther applied directly or through the intervention of the air or the water, is sufficient for the dissolution of all the ice produced in the course of the autumn, the winter and the spring. It may be proved by experiment that, under the Pole itself, the power of the sun at the solstice could, in the space of a week, melt a stratum of five inches of ice. We may hence fairly compute the annual effect to be sufficient for thawing to the depth of forty inches. It should likewise be observed, that, owing to the prevailing haziness of the atmosphere in the northern latitudes, those singular cold emanations which al

ways dart from an azure sky, and in the more temperate climates diminish the calorific action of the sun often by one. fifth part, can scarcely exist. On this account, perhaps the estimate of the annual destruction of Polar ice may be swelled to a thickness of four feet.

THE MAELSTROM.

THE Maelstrom, a very dangerous whirlpool on the coast of Norway, in the 68th degree of latitude, in the province of Nordland, and the district of Lofoden, and near the island of Moskoe, from whence it also takes the name of Moskoe-strom. Its violence and roarings exceed that of a cataract, being heard to a great distance, and without any intermission, except a quarter every sixth hour, that is, at the turn of high and low water, when its impetuosity seems at a stand, which short interval is the only time the fishermen can venture in; but this motion soon returns, and, however calm the sea may be, gradually increases with such a draught and vortex, as absorb whatever comes within their sphere of action, and keep it under water for some hours, when the fragments, shivered by the rocks appear again. This circumstance, among others, makes strongly against Kircher and others, who imagine that there is here an abyss penetrating the globe, and issuing in some very remote parts, which Kircher is so particular as to assign, for he names the gulf of Bothnia. But after the most exact researches which the circumstances will admit, this is but a conjecture without foundation; for this and three other vortices among the Ferroe islands, but smaller, have no other cause than the collision of waves rising and falling, at the flux and reflux, against a ridge of rocks and shelves, which confine the water so that it precipitates itself like a cataract; and thus the higher the flood rises, the deeper must the fall be; and the natural result of this is a whirlpool or vortex, the prodigious suction whereof is sufficiently known by lesser experiments. But what has been thus absorbed, remains no longer at the bottom than the ebb lasts; for the suc tion then ceases, and the flood removes all attractions, and permits whatever had been suuk to make its appearance again. Of the situation of this amazing Moskoe-strom we have the following account from Mr. Jonas Ramus: "The mountain of Helseggen, in Lofoden, lies a league from the

island Ver, and betwixt these two runs that large and dreadful stream called Moskoe-strom, from the island Moskoe, which is in the middle of it, together with several circumjacent isles as Ambaaren, half a quarter of a league northward, Iflesen, Hocholm, Kieldholm, Suarven, and Buckholm. Moskoe lies about half a quarter of a mile south of the island of Ver, and betwixt them these small islands, Otterholm, Flimen, Sandflesen, Stockholm. Betwixt Lofoden and Moskoe, the depth of the water is between thirty six and forty fathoms; but on the other side, towards Ver, the depth decreases, so as not to afford a convenient passage for a vessel, without the risk of splitting on the rocks, which happens even in the calmest weather when it is flood, the stream runs up the country between Losoden and Moskoe with a boisterous rapidity: but the roar of its impetuous ebb to the sea is scarce equalled by the loudest and most dreadful cataracts; the noise being heard several leagues off, and the vortices or pits are of such an extent and depth, that if a ship comes within its attraction, it is inevitably absorbed and carried down to the bottom, and there beat to pieces against the rocks; and when the water relaxes, the fragments thereof are thrown up again. But these intervals of tranquility are only at the turn of the ebb and flood, and calm weather: and last but a quarter of an hour, its vio. lence gradually returning. When the stream is most boisterous, and its fury heightened by a storm, it is dangerous to come within a Norway mile of it: boats, ships, and yachts having been carried away, by not guarding against it before they were within its reach. It likewise happens frequently, that whales come too near the stream, and are overpowered by its violence; and then it is impossible to describe their howlings and bellowings in their fruitless struggles to disengage themselves. A bear once attempting to swim from Losoden to Moskoe, with a design of preying upon the sheep at pasture in the island, afforded the like spectacle to the people; the stream caught him, and bore him down, whilst he roared terribly, so as to be heard on shore. Large stocks of firs and pine trees, after being absorbed by the current, rise again, broken and torn to such a degree as if bristles grew on them. This plainly shows the bottom to consist of craggy rocks, among which they are whirled to and fro. This stream is regulated by the flux and reflux of the sea; it being constantly high and low water every six hours. In the year 1645, early in the morning of Sexagesima Sunday, it raged with such noise and impetuosity, that on the island of Moskoe, the very stones of the houses fell to the ground."