Captain Scoresby relates a similar narrow escape from destruction owing to the same cause.  “In the year 1804,” he observes, “I had an opportunity of witnessing the effects produced by the lesser masses in motion.  Passing between two fields of ice newly formed, about a foot in thickness, they were observed rapidly to approach each other, and, before our ship could pass the strait, they met with a velocity of three or four miles per hour.  The one overlaid the other, and presently covered many acres of surface.  The ship proving an obstacle to the course of the ice, it squeezed up on both sides, shaking her in a dreadful manner, and producing a loud grinding or lengthened acute trembling noise, according as the degree of pressure was diminished or increased, until it had risen as high as the deck.  After about two hours the motion ceased, and soon afterwards the two sheets of ice receded from each other nearly as rapidly as they had before advanced.  The ship in this case did not receive any injury; but, had the ice only been half a foot thicker, she might have been wrecked.”  Other navigators have not been so fortunate; and the annual loss of whaling vessels in the polar seas is considerable, the Dutch having had as many as seventy-three sail of ships wrecked in one season.  Between the years 1669 and 1778, both inclusive, or a period of one hundred and seven years, they sent to the Greenland fishery fourteen thousand one hundred and sixty-seven ships, of which five hundred and sixty-one, or about four in the hundred, were lost.

Every one will remember the intense and mournful interest occasioned by the loss of the President steamer which left New York in the year 1841 to cross the Atlantic, but perished in the passage, without leaving a survivor to tell the story of her fate.  It has been deemed highly probable that this vessel got entangled in the ice, and was destroyed by collision with its masses; for during that year, in the month of April, the Great Western steamer encountered a field extending upwards of a hundred miles in one direction, surrounded with an immense number of floes and bergs, and had great difficulty in effecting its passage by this floating continent in safety.

Another form under which the ice appears in the ocean is that of bergs, which differ from the ice-fields in shape and origin.  They are masses projecting to a great height above the surface of the water, and have the appearance of chalk or marble cliffs and mountains upon the deep.  They have been seen with an elevation of two hundred feet—­a circumference of two miles:  and it has been shown by experiments on the buoyancy of ice floating in sea water, that the proportion above the surface is only about one-seventh of the thickness of the whole mass.  During the first expedition of Ross, he found an ice berg in Baffin’s Bay, at a distance of seven leagues from the land, which was measured by a party under Lieutenant Parry.  Considerable difficulty was experienced in the attempt to land,