It is not easy to form an adequate conception of these truly wonderful productions of nature. Their magnitude, their beauty, and the contrast they form with the gloomy rocks around, produce sensations of lively interest. Their upper surfaces are generally concave; the higher parts are always covered with snow, and have a beautiful appearance, but the lower parts, in the latter end of every summer, present a bare surface of ice. The front of each, which varies in height from the level of the ocean to four hundred or five hundred feet above it, lies parallel with the shore, and is generally washed by the sea. This part, resting on the strand, is undermined to such an extent by the sea, when any way turbulent, that immense masses, loosened by the freezing of water, lodged in the recesses in winter, or by the effect of streams of water running over its surface and through its chasms in summer, break asunder, and, with a thundering noise, fall into the sea. On an excursion to one of the Seven Icebergs, in July, 1818, I was particularly successful in witnessing one of the grandest effects which these Polar glaciers ever present. A strong north-westerly swell having, for some hours, been beating on the shore, had loosened a number of fragments attached to the iceberg, and various heaps of broken ice denoted recent shoots of the seaward edge. As we rode towards it, with a view of proceeding close to its base, I observed a few little pieces fall from the top, and, while my eye was fixed on the place, an immense column, probably fifty feet square, and one hundred and fifty feet high, began to leave the parent ice at the top, and leaning majestically forward with an accelerated velocity, fell with an awful crash into the sea. The water into which it plunged was converted into an appearance of vapour, or smoke, like that from a furious cannonading. The noise was equal to that of thunder, which it nearly resembled. The column which fell was nearly square, and in magnitude resembled a church. It broke into thousands of pieces. This circumstance was a happy caution, for we might inadvertently have gone to the base of the icy cliff, from whence masses of considerable magnitude were continually breaking.