Page:Physical Geography of the Sea and its Meteorology.djvu/81

 Rh of the Gulf Stream may be; but assuming the temperature and velocity at the depth of two hundred fathoms to he those of the surface, and taking the well-known difference between the capacity of air and of water for specific heat as the argument, a simple calculation will show that the quantity of heat discharged over the Atlantic from the waters of the Gulf Stream in a winter's day would be sufficient to raise the whole column of atmosphere that rests upon France and the British Islands from the freezing point to summer heat.

153. Contrasts of climates in the same latitudes.—Every west wind that blows crosses this stream on its way to Europe, and carries with it a portion of this heat to temper there the northern winds of winter. It is the influence of this stream upon climate that makes Erin the "Emerald Isle of the Sea,"—that clothes the shores of Albion in evergreen robes; while in the same latitude, on this side, the coasts of Labrador are fast bound in fetters of ice. In a valuable paper on currents, Mr. Redfield states, that in 1831 the harbour of St. John's, Newfoundland, was closed with ice as late as the month of June; yet who ever heard of the port of Liverpool, on the other side, though 2° farther north, being closed with ice, even in the dead of winter?

154. Mildness of an Orkney winter.—The Thermal Chart (Plate IV.) shows this. The isothermal lines of 60°, 50°, etc., starting off from the parallel of 40° near the coasts of the United States, run off in a north-eastwardly direction, showing the same oceanic temperature on the European side of the Atlantic in latitude 55° or 60° that we have on the western side in latitude 40°. Scott, in one of his beautiful novels, tells us that the ponds in the Orkneys (latitude near 60°) are not frozen in winter. The people there owe their soft climate to this grand heating apparatus, and to the latent heat of the vapours from it which is liberated during the precipitation of them upon the regions round about. Driftwood from the West Indies is occasionally cast upon the islands of the North Sea and Northern Ocean by the Gulf Stream.

155. Amount of heat daily escaping through the Gulf Stream.—Nor do the beneficial influences of this stream upon climate end here. The West Indian Archipelago is encompassed on one side by its chain of islands, and on the other by the Cordilleras