Page:Physical Geography of the Sea and its Meteorology.djvu/122

96 shorter period of excessively warm weather. Thus we infer the existence in the upper air of reservoirs for the heat as well as of chambers for the cold.

249. The warm winds of the Andes caused by the trade-winds.—The streaks of warm air on the Andes (§ 246) derive their warmth in all probability from the liberated heat of the trade-wind vapours as they are condensed into snow-storms.

250. Dormant powers of the telegraph in meteorology.—Spells of wet and dry, as well as "terms" of hot and cold, weather sometimes pass over portions of the country like great waves. They occupy hours, or days, or weeks in their march. The magnetic telegraph would, were the system of combined research out of which this work has grown so enlarged as to permit us to use it as a meteorological implement, enable us to give warning of all such changes in the weather in time for farmers and others, as well as mariners to profit by the foreknowledge. We could foretell the coming of storms also.

251. The wind in his circuits.—We now see the general course of the "wind in his circuits," as we see the general course of the water in a river. There are many abrading surfaces, irregularities, &c., which produce a thousand eddies in the main stream; yet, nevertheless, the general direction of the whole is not disturbed nor affected by those counter-currents; so with the atmosphere and the variable winds which we find here in