rise, must overflow above, and must force the colder air from the surrounding regions in below. Two sheets of air will thus set in vertically on both sides, rise, and again separate above. Here was an explanation of the great, steady, uninterrupted aërial currents which, at the rate of from fifteen to eighteen miles per hour, sweep the surface of the Atlantic and Pacific oceans. The candle, no doubt, was wasted, but the secret of the trade-winds was discovered. The idea was correct as far as it went. It did not go very far, it is true. It had not taken into account the earth's rotation, whose force, according to Herschel, "gives at least one-half of their average momentum to all the winds which occur over the whole world;" nor the infinite variation in the movements of the atmosphere which we call winds, caused by the change in the sun's motion, by the differing amounts of vapor held in them, by the physical configuration of the earth below, by the vicinity of the sea or arid deserts, and by the passage of storms or electric currents. The science of meteorology, especially as regards wind, is as yet searching for general principles, which can only be deduced from countless facts. We do not now, like Saint Paul, talk of the wind Euroclydon as of a special agent of God, but describe it by stating that it is an aërial ascending current over the Mediterranean, produced by the heated sands of Africa and Arabia. We can even measure its heat at 200° Fahrenheit, and its velocity at fifty-four miles per hour. But it attacks us just as unexpectedly as it did the apostle, and brings disease and death to Naples or Palermo to-day just as surely as it did to Cambyses. The popular verdict on the matter would no doubt be that when meteorologists can not only describe the sirocco, but give warning of its coming, their science will justify its claim to consideration. The common sense of mankind always demands as a royalty from every science daily practical benefits to the mass of men and women. It is not enough for meteorologists to have proved that the atmosphere varies in weight, in temperature or velocity of motion according to fixed rules, or to be able to explain why no rain falls on a certain portion of the coast of Portugal, while a like coast-exposure in England is incessantly drenched; or to have determined beyond a doubt that precisely as the ocean of water, under the influence of the moon and wind, ebbs and flows and has its succession of storms or calms, the ocean of air in which we are enveloped answers to the influence of the sun in great tidal movements, and has also its vast steadily moving waves of cold or heat or moisture. These discoveries of general truths must be brought to bear directly on men's daily life before they will have fulfilled their true purpose. It would seem as if nothing were more easy than to bring them so to bear. Meteorology, more intimately perhaps than any other science, concerns our ordinary affairs.