WHIRLWIND.
Lay-boay,. . . . BURM. I Gird bad, . . . . PERS. Devil wind, . . . ENG. I Peshash, . . . . TAm.
The whirlwinds which occur in the desert west of Kharan, near Ragan in Baluchistan, would perhaps be more correctly called by some other name. They are vast columhs of sand, which begin by a trifling agitation with a revolving motion on the surface of the desert, and gradually ascend and expand, until the tops of them are lost to the view, in which manner they move about with every breath of wind like a pillar of sand. Lieut. Pottinger saw at the sanie time 30 or 40 of them of different dimensions, apparently from 1 to 20 yards in diameter. Those who have seen a water spout at sea may exactly conceive the same formed of sand on shore. Whirlwinds arc extremely com mon in the Panjab, and in the central parts of the Peninsula of India, and some of them are supposed to be owing to electric action. Dr. Adams, writing of theni, observes that about noon, when the west wind sets in, clouds of sand sweep across the country, penetrating through the minutest chinks and crevices. Whirlwinds are then of frequent occurrence. At a distance they look like re volving clouds of smoke, shooting upwards fully 200 feet. These cycloidal movements often last for upwards of half an hour, and carry with them whatever light substance they ,may encounter ; after gliding along for distance they finally disappear. The meeting of two opposite currents of air is no doubt at times the cause, inasmuch as a whirlwind was always seen to commence at the corners of two tancret of buildings placed at right angles to each other. The following note of the loss of polarity by the needle during a whirlwind is given in a letter in the Bombay Times, May 30, 1846 :— • There is a class of magnetic local perturbations apparen,tly confined to these seas, qne of which was ex perienced by the Queen on her late voyage from Aden, which we do not remember to have seen noticed by magneticians. -When about three hundred miles from
Bombay, the people on board the steamer observed the atmosphere get suddenly clouded all around with that strange lurid appearance which indicates the approach of burst of rain or hurricane. By and by appeared overhead those strange and turbulent vapours corn inonly attendant on a whirlwind or waterspout, and a light whirlwind accordingly made its appearance. At this time the magnetic virtue of the compass appeared to vanish : the needle lost its polarity and traversed equally in all directions. A state of matters so sur prising was of short endurance ; the sky cleared with out a tempest, and all went well again. It was, we think, about A.D. 1844, that an incident of this sort was met with by the H. C. schooner .11/a/ti on her way from the Persian Gulf. She was surrounded by beauti ful groups of whirlwinds and waterspouts ranging, about her in all directions, when suddenly the needle lost its polarity, and continued for some time useless for the purpose of steering.' Dr. Bradley has clearly established the fact that the lesser whirlwinds at all events are either due to direct electrical agency, or are characterized by the most striking electrical exhibitions.— Pottinger's Tr.; Adams.