Lieutenant Maury, in his Physical Geography of the Sea, has boldly likened the causes at work to produce the celebrated Gulf-stream to the mechanical arrangements by which apartments are heated. The furnace is the torrid zone, the Mexican Gulf and the Caribbean Sea are the caldrons, and the Gulf-stream is the conducting-pipe by which the warm water and the air above it, are dispersed to the banks of Newfoundland and to the north-western shores of the old world.[28] By this beneficent process the cold of our northern latitudes is greatly ameliorated. The waters sent north and north-east are edged by return currents, the one finding its way close to the banks of Newfoundland and along the seaboard of the States, and the other returning by the North Sea, the Bay of Biscay, and the west coast of Africa, until about the latitude of the Cape de Verdes it crosses westward again to fill up the void caused by the waters issuing from the Gulf of Florida. Thus the grand circuit is for ever maintained, not always, however, exactly in the same form, but varying according to the season. In the winter, the cold current coming S.S.W. along the Atlantic coast of North America is greatly augmented, and pushes the Gulf-stream further to the south-east. With the return of summer this stream, in its turn, thrusts aside the waters coming from the Polar Ocean. Between these two periods the trough of the Gulf-stream, to use Lieutenant Maury's forcible expression, "wavers about in the ocean like a pennon in the breeze." The temperature of the Gulf-stream, even in the winter, is at the summer level as it runs between two walls of nearly ice-cold water. Sir Philip Brooke found the air on either side of it at the freezing point, at the same time that that of the stream was at 80°. This difference in the temperature of air and water is probably the cause of those terrible hurricanes that occur in the Atlantic and among the West-Indian Islands, and which make it the most dangerous navigation, during the winter, in the world. The average of wrecks on the Atlantic seaboard of the United States during these rigorous months is not less than three a day. Sailors term the Gulf-stream "The weather-breeder;" and well they may, considering its frightful effect in producing commotion in sea and air. In Franklin's time it was no uncommon thing for vessels bound in winter for the Capes of Delaware to be blown off land, and forced to go to the West Indies, and there wait for the return of spring before they could attempt to make for this point. The snow-storms and the furious gales which greet the ship as she leaves the warm waters of the Gulf and nears the shores of North America, are quite dramatic in their effect. One day she is sailing through tepid water, and enjoying a summer atmosphere, the next, perhaps, driving before a snow-storm, her rigging a mass of icicles, and her crew frozen by the piercing blast. The Gulf-stream is answerable for another