Page:Popular Science Monthly Volume 28.djvu/325

Rh Maury, in an article entitled "Tornadoes and their Causes," attributes the peculiar movement of our tornadoes to an upper air-current, which at times has been seen to be "moving from the southwest at the rate of one hundred miles an hour." In addition to this, Lieutenant Finley's descriptions of the thirteen tornadoes that occurred in Kansas, May 29 and 30, 1879, give abundant evidence that the southwest air-current forces the contest. Innumerable descriptions show that the cloud in the northwest is heavy, black, and comparatively slow in its movement, until struck by a light, rather smoky, and more rapidly moving cloud from the southwest. Then the clouds rush to a common center, and there is a violent conflict of currents, driving clouds in every direction, up and down, round and round. Clouds like great sheets of white smoke dash about in a frightful manner, with such unnatural velocity that the observer is often panic-stricken, and flees to the nearest cellar for safety. Finally a black, threatening mass descends slowly toward the earth, whirling violently, but still manifesting confusion in form. This soon gives place to the peculiar funnel-like shape, with definite outline so well known. It appears intensely black, like coal-smoke issuing from a locomotive, and its trunk-like form sometimes has a wrenching, spiral motion, like a snake hung up by the head and writhing in agony. As white clouds approach and are drawn into the vortex, the funnel-shaped trunk sways like an elastic column. It sometimes rises, falls, and careens from side to side like a balloon. Branches and trunks of trees, rails, tree-tops, roofs, pieces of houses, straw, furniture, stoves, iron-work, lumber, and other débris are seen flying about in the central part of the cloud, but are gradually drawn upward and thrown out near the top, usually not until the storm has progressed a mile or two farther on from a given point. Dark masses of cloud are seen to shoot downward on either side of the funnel, to enter it just above the ground, and to apparently rush upward through the center and out at the top in a terrific manner. Sometimes the funnel pauses and whirls with apparently increased velocity, reducing everything to splinters, and leaving scarcely a vestige of a house or clump of trees, all being ground comparatively fine and carried away as chaff. At Westwood, New Jersey, October 4, 1885, fully three quarters of a school-house was carried away from the foundation. Its fragments were scattered along the storm's track for about half a mile, and the rest was seen no more. The people at Westwood describe the roar of the tornado as having a peculiar hollow, humming sound. It somewhat resembled the rumbling of cars, or the booming of the sea. The sound is indescribable and unlike any other in Nature. It is so loud that the falling of heavy trees against the side of a house and the crash of falling buildings are lost in the general roar. These facts attest the tremendous rapidity of the air-currents.

In addition to a downward movement of air, there is also a violent