Since then there has been only a partial revival, accompanied by a good many changes. A few Scotch and German whalers still go to the northern seas, working in the ice, and some American vessels from the Eastern States, and a greater number from California search the Pacific and the waters off Alaska. All or nearly all of these whalers are provided with steam-propellers, having an arrangement by which they can lift the screw out of water and use their sails for ordinary purposes. Many of them chase with a steam-launch instead of the old-fashioned whaleboats, and save their men the back-straining labor of towing a prize perhaps two or three miles to the ship. In place of the hand harpoon they have several forms of swivel-guns and shoulder-guns discharging harpoons and explosive darts by gunpowder, so that a large share of the danger as well as the labor is saved to modern whalemen, who are also much better housed and fed in their large iron steamships than those used to be who wrestled with scurvy in the grim old hulks of half a century ago. The ships that go up through Davis Straits now frequently winter there, in order to be on hand in May to meet the whales that appear in the first open water, to which the men drag their boats over the ice between their ships and the first open channels. For the same purpose many vessels of the American fleet are accustomed to pass the winter in company under the shelter of islands near the mouth of the Mackenzie River. Here they have a rendezvous where buildings have been erected and means for social comfort have been established, such as billiard tables, books, etc. These western vessels do not force their way into and through the ice, as do those among the eastern archipelagoes, but operate in comparatively open water, as long as it lasts, along the edge of the paleocrystic ice. Delaying the departure of those who mean to return to the Pacific and home until the last moment, it occasionally happens that some are caught and frozen in. These are usually destroyed, but thus far their crews have managed to escape either to more fortunate vessels or to the shore, where, at Point Barrow, the government has built and keeps furnished a strong house, with stores, fuel, and provisions, as a refuge for shipwrecked mariners. Walrus-hunting is not much followed nowadays by civilized seamen, though the animal is still of great value to the Eskimo and Siberians. It has become very scarce in easily accessible waters, but is occasionally taken by whalers, who find a market for the ivory of its tusks.