Some observations by Back on the gradual growth of ice, by layers forced together above or underneath, will explain the apparent discrepancies in Arctic works, where one reads of ice of so many different thicknesses formed in the same winter. It is probable that the very thick ice found in many parts of floes is formed by an accumulation of such layers, cemented together in bights or bays, sheltered by projecting capes or headlands, and less liable to disturbance from currents and tides; for they had ocular demonstration, that with a very low temperature and calm weather, in the severest portion of the winter, no addition of bulk takes place from the surface downwards when protected, as their floe was, by a hard coating of snow and drift. The doubling and packing of ice during gales of wind and when exposed to severe pressure, as well as the growth and the extensive fields, are phenomena which the attentive observations of modern voyagers have rendered familiar; and by an extension of the above remark, another explanation besides the action of the waves (for the mere heat of the sun has little influence) is afforded as to how the destruction of the immense fields of ice is effected, not, indeed, by pointing out the agents of the destruction, but by showing how little may in many instances be added in successive winters to the bulk to be destroyed. The fact that no new deposition takes place underneath seems also at once to account for the decayed and wasting appearance, which every one accustomed to polar navigation must have noticed in what is called the old ice, of which sailors will sometimes say—“Aye, sir, that piece is older than I am, but it cannot last above another summer.” The writer well remembers the idea of age, in another form, being associated with snow: “That there snow,” said one of the sailors to him, “is three hundred year old, if it’s a day. Why, don’t you see the wrinkles all over the face of it?” Every one has noticed the wrinkles and ridges in snow, but the idea of associating great age with them was original.