Far within the borders of compact ice the atmosphere, in summer, is often cloudless, and the weather serenely pleasant, though cold. But in the usual fishing-stations, and on the exterior of the ice in general, a clear sky is not frequent; nevertheless, when it does occur, its transparency is peculiarly beautiful. The sun sometimes sweeps two or three times round the Pole, without being for a moment obscured by a cloud. Objects the most remote may be seen perfectly distinct and clear. A ship’s top-gallant-mast, at the distance of five or six leagues, may be discerned when just appearing above the horizon, with a common perspective glass; and the summits of some mountains are visible at the distance of sixty to a hundred miles. This perfect clearness occurs most frequently before easterly winds; in general, however, especially in very cold weather, objects on the horizon, when viewed with a high magnifier, appear affected with a perpetual tremor; whence the contemplation of distant objects is accomplished as perfectly with a good pocket-glass as with the best telescope. This tremulous motion is evidently produced by the quantity of delicate icy crystals which, in very low temperatures, are almost always seen floating in the air. The general obscurity of the atmosphere, arising from clouds or fogs, is such, that the sun is frequently invisible during several successive days. At such times, when the sun is near the northern tropic, there is scarcely any sensible variation in the quantity of light from noon to midnight. Hence, when the sailors have been long abroad in the boats, or so fully engaged as to be unable to mark the progress of time, the inquiry, whether it be day or night, is not unfrequent. There is nothing remarkable in the appearance of the sun at midnight, excepting that, when its altitude is very small, it may be viewed with the naked eye, without producing any painful sensation; but when it is more than four or five degrees above the horizon, it generally appears as effulgent as with the same elevation in Britain. The force of the sun’s rays is sometimes remarkable. Where they fall upon the snow-clad surface of the ice or land, they are, in a great measure, reflected, without producing any material elevation of temperature; but when they impinge on the black exterior of a ship, the pitch on one side occasionally becomes fluid, while ice is rapidly generated on the other; or, while a thermometer, placed against the black paint-work on which the sun shines, indicates a temperature of 80° or 90°, or even more, on the opposite side of the ship a cold of 20° is sometimes found to prevail.