Arabia upon the winds is felt in Austria and other parts of Europe, as the observations of Kriel, Lamont, and others show. So, also, do the islands, such as the Society and Sandwich, that stand far away from any extent of land, have a very singular but marked effect upon the wind. They interfere with the trades very often, and turn them back; for westerly and equatorial winds are common at both these groups in their winter-time. Some hydrographers have even taken those westerly winds of the Society Islands to be an extension of the monsoons of the Indian Ocean.
697. Influences of coral reefs upon winds.—It is a curious thing is this influence of islands in the trade-wind region upon the winds in the Pacific. Every navigator who has cruised in those parts of that ocean has often turned with wonder and delight to admire the gorgeous piles of cumuli, heaped up and arranged in the most delicate and exquisitely beautiful masses that it is possible for fleecy matter to assume. Not only are these cloud-piles found capping the hills among the islands, but they are often seen to overhang the lowest islet of the tropics, and even to stand above coral patches and hidden reefs, "a cloud by day," to serve as a beacon to the lonely mariner out there at sea, and to warn him of shoals and dangers which no lead nor seaman's eye has ever seen or sounded out. These clouds, under favourable circumstances, may be seen gathering above the low coral island, and performing their office in preparing it for vegetation and fruitfulness in a very striking manner. As they are condensed into showers, one fancies that they are a sponge of the most delicately elaborated material, and that he can see, as they "drop down their fatness," the invisible but bountiful hand aloft that is pressing it out.—Maury's Sailing Directions, 7th ed., p. 820.
698. Monsoons in miniature.—Land and sea breezes are monsoons in miniature, for they depend in a measure upon the same cause. In the monsoons, the latent heat of vapour which is set free over the land is a powerful agent. In the land and sea breezes, the heat of the sun by day and the radiation of caloric by night are alone concerned. In the monsoons the heat of summer and cold of winter are also concerned. But could the experiment be made with two barometers properly placed—one at sea and the other on land, but both within the reach of land and sea breezes—they would show, I doubt not, regular altera-
