Page:Popular Science Monthly Volume 41.djvu/811

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.
791
A CHAPTER IN METEOROLOGICAL DISCOVERY.

pared his facts, before lie published his theory of storms. He noted the occurrence of several great gales, and set about collecting all the facts possible in reference to them, carrying on a wide correspondence, and examining a multitude of witnesses. He sought out the marine reports as to all vessels coming into port soon after the storm, examined their log-books and talked with their captains. In the case of the great Cuban hurricane of 1844, he collated one hundred and sixty-four different accounts. He noted the latitude and longitude of the vessels at sea, or the observers on the coast, when they took the gale, the direction and force of the wind as they experienced it, the direction in which it veered, the states of the barometer, and all cognate facts. Then he charted the whole and studied its meaning.

It was in 1831, ten years from the time in which he first observed the effects of the September gale and drew his inferences from them, that he published an article, "On the Prevailing Storms of the Atlantic Coast." In it he gave an account of the gale of 1821, which he describes as "exhibited in the form of a great whirlwind." He had now made several important conclusions in reference to this class of storms: 1. He held that they often originate in the tropical latitudes, frequently to the north and east of the West India Islands. 2. That they often cover at the same moment of time an area of from one hundred to five hundred miles in diameter, and that they are most violent nearest the center of this area, and least energetic about the exterior lines. 3. That while in the tropics these storms move from east to west till they reach the parallel of 30 north, when they suddenly recurve to the north and east, and move rapidly along lines generally parallel with the Atlantic coast of the United States. 4. That the direction of the winds along the greater portion of its storm-tracks is not the same as the direction of the storm itself. 5. That when in these northerly latitudes these storms, while moving in a northeast course, begin with a wind from east to south, and terminate with a wind from west to north. 6. That on the outer portion of the track, north of the parallel of 30 or within that portion lying farthest from the American coast, these storms exhibit at the commencement a southerly wind which, as the storm comes over, veers gradually to the westward, a quarter where it is found to terminate. 7. In the same latitudes, but along the central portion of the track, the first force of the wind is from the southeast, but after blowing for a certain period it changes suddenly to a point nearly or directly opposite. 8. On that portion of the track nearest the American coast or farthest inland, if the storm reaches the continent, the wind commences from an east or northeast point and veers more or less gradually by north to northwest.