Page:McCosh, John - Advice to Officers in India (1856).djvu/104

 air is stirring, four, six or more of such columns may be counted at one time. A spiral column of dense dust first makes it appearance on the ground, with abase of ten or twelve feet diameter, and gyrations from twenty to forty in a minute. Every light body is caught in its eddies, and twisted up with great velocity to the sky. Its onward motion is crooked and irregular, perhaps only one or two miles an hour, and the noise as it advances resembles the crackling of a large fire. The atmosphere beyond the gyrations is not in the least agitated; and one may walk in company with it, only a few yards apart, and watch its phenomena without being sensible of its force or sprinkled with its dust. After traversing the earth for a mile or two, it gradually becomes expended, and its tract remains on the sky for some time after all is quiet on the ground. I feel at a loss to account for such winds by any known theory, though the cause is probably the same as that of the waterspout: they occur only in calm weather, and are not known in a stormy day, nor does either thunder or lightning accompany them, or any change of weather follow them. These whirlwinds strikingly exemplify the lately-discovered law of storms, though only in miniature; and I have no doubt if their scientific authors were in the Punjaub, they would be able to make most valuable notes in their horn book.