There is no doubt that a large quantity of ice is annually generated in the bays and amidst the islands of Spitzbergen; which bays, towards the end of summer, are commonly emptied of their contents, from the thawing of the snow on the mountains causing a current outwards. But this will not account for the immense fields which are so abundant in Greenland. These evidently come from the northward, and have their origin between Spitzbergen and the Pole. Ice-fields constitute one of the wonders of the deep. They are often met with of the diameter of twenty or thirty miles, and when in the state of such close combination that no interstice could be seen, they sometimes extend to a length of fifty or a hundred miles. The ice of which they are composed is generally pure and fresh, and in heavy fields it is probably of the average thickness of ten to fifteen feet, and then appears to be flat, low, thin ice; but when high hummocks occur, the thickness is often forty feet and fifty feet. The surface before the month of July is always covered with a bed of snow, from perhaps a foot to a fathom in depth. This snow dissolves in the end of summer, and forms extensive pools and lakes of fresh water. Some of the largest fields are very level and smooth, though generally their surfaces are varied with hummocks. In some, these hummocks form ridges or chains, in others, they consist of insulated heaps. I once saw a field which was so free from either fissure or hummock, that I imagined, had it been free from snow, a coach might have been driven many leagues over it in a direct line, without obstruction or danger. Hummocks somewhat relieve the uniformity of intense light reflected from the surface of fields, by exhibiting shades of delicate blue in all the hollows, where the light is partly intercepted by passing through a portion of ice. When the surface of snow on fields is frozen, or when the snow is generally dissolved, there is no difficulty in travelling over them, even without snow-skates or sledges. But when the snow is soft and deep, travelling on foot to any distance is a work of labour. The tribe of Esquimaux, discovered by captain Ross, made use of sledges, drawn by dogs, for conveying them across the rough land-ice, lying between the ships and the shore. A journey they performed with such celerity, that captain Ross conjectured they could travel fifty or sixty miles a day. If such a distance were practicable on drift-ice, occurring near shore, it would be much more easy on the smoother ice of fields.