Page:Transactions of the Provincial Medical and Surgical Association, volume 4.djvu/211

 Rh in the barometer, and a fall in the temperature of the dew-point, take place at the same time, we may conclude that the expansion which occasions the former has arisen at some distant place, and wind, not rain, will be the result.

4. Wind.—The hills at Malvern influence so much the force and direction of the wind, that it is often very difficult to determine precisely the point whence the great atmospheric current comes; it is not always that there are clouds by which to determine; besides, when these are high, it not infrequently happens that they are subjected to the movements of the higher currents, and passing away in a direction quite opposite to the wind below. The determination of the precise point from which the wind blows is not very material, provided the following circumstances are borne in mind, as influencing in a very marked degree, not only the temperature of the wind, but the elasticity of the vapour it bears with it.

From north to east, Great Britain is bounded by the Arctic Ocean, the cold mountainous regions of Sweden and Norway, with other portions of the continents of Europe and Asia; from south to west, by the southern Atlantic Ocean; from north to west, by the North Atlantic, and the distant shores of America; from south to east, by the warmer regions of Europe, &c.

From these circumstances, and from the general fact that winds blowing over large tracts of land are cooler than those coming from off the ocean, it results that in this country north-east winds are