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Concerning this most important element in which we live and move and have our being, Pliny, in the first century of our era, wrote as follows: "It is time to consider the other marvels of the heavens; thus our fathers called that immense space where flows the vital fluid to which we give the name of air, and which is not apparent to the senses because of its great rarity. There clouds form, thunder and lightning also; it is the region of tempests and of whirlwinds; from there fall rains, hail, and hoar frost; from there come all those phenomena, astonishing and often disastrous, which follow the combat of Nature with herself…. The sun's rays strike the earth on all sides, warming and strengthening it; they are reflected and detach all the particles they can carry away; vapours descend and rise again; the winds come empty and return laden with spoil; animals breathe in from above this vital fluid which animates them, and the earth sends it back to its source as if she would fill the void by this means. So, by Nature acting everywhere and in all directions there results an apparent discord from which is born the harmony of the Universe; it is this general movement which puts all things in their places; some are preserved by the destruction of others; all move, all act, the struggle is continual, if it ceased an instant everything would fall into chaos…."

From the earliest times, as far back as history extends, we find mankind interested in meteorological phenomena. This appears natural if we consider the importance of the weather to the ancient pastoral nations, which, from the open-air life and keen perceptive faculties of their people, were well fitted to study natural phenomena. The beauty and grandeur of many of the phenomena occurring in the atmosphere, and the curiosity excited concerning their causes, probably contributed to interest people in them. Meteorology appears to have been first treated systematically, as distinct from astronomy and astrology, by the Greek philosopher, Aristotle, more than 2000 years ago. The word "meteor," derived from the Greek "elevated," was applied to certain phenomena having their origin in the atmosphere. These were classified into aërial, aqueous, and luminous meteors, and were all included in the term Meteorology. In his treatise by this name Aristotle gave a more detailed account of them than any preceding or contemporary writer, and Theophrastus, his pupil, wrote two books on the winds and on the signs of rain, which have been translated into Latin and English. About the same period Aratus incorporated the current weather proverbs in his poem, Diosemeia. The Greek historians and poets frequently alluded to atmospheric phenomena, and their example was followed by the Romans, of whom Pliny has been quoted.

No doubt the desire to ascend into the air always possessed man, but owing to the awe with which mountains seem to have inspired the ancients, there is rarely mention in their writings of climbing mountains, or of the physiological effects which could hardly have failed to be apparent upon high summits. Citing one of the few existing narratives, Aristotle relates: "Those which ascend to the top of the mountain Olympus could not keep themselves alive without carrying with them wet sponges, by whose assistance they could respire in that air otherwise too thin for respiration." This mountain of less than 10,000 feet was said to be so high that it never rained on its summit, where, it was supposed, the air was always still. A still higher mountain, easily accessible to the ancient world, and which we know was ascended, is Etna.

Concerning the progress of meteorology, from the time of the ancient Romans to the revival of knowledge in Europe, there is little to say except that during the middle ages meteorology, like other learning, was confined to the monasteries. Speculations were current as to the extent of the atmosphere until, in the middle of the eleventh century, Alhazen, a learned Arab, computed from the duration of twilight that the atmosphere extended nineteen leagues above the earth. The same method was applied with more precision by Tycho Brahe, Kepler, and other