Page:Popular Science Monthly Volume 13.djvu/653

Rh females lay their eggs for another brood of larvæ. The Anthrenus once introduced into a house quickly infests it in every part. Thus, in a house at Cold Spring, New York, which had remained shut up for twelve months, they "took complete possession from the cellar to the attic, in every nook and crevice of the floors, under matting and carpets, behind pictures, eating everything in their way." No effectual means of combating this insect pest has yet been discovered; they are said to "grow fat" on camphor, pepper, tobacco, turpentine, carbolic acid, and the other ordinary applications.

The Earthquake-Scare in North Carolina.—Bald Mountain, in Western North Carolina, forming part of the Blue Ridge of the Alleghanies, has for two or three years been receiving a good deal of attention in the newspapers. Rumbling noises have now and then been heard in the mountain, and these were by the people of the surrounding country taken to be conclusive evidences of volcanic action. As is usual in such cases, these actual phenomena were magnified enormously by the popular imagination, and to them were added others which had no objective existence. Prof. Clarke, of the University of Cincinnati, having devoted the early days of his summer vacation this year to investigating the causes of these rumblings, declares, in a letter to the New York Tribune, that "Bald Mountain is no more an earthquake centre than is Central Park," and that "it is merely a locality in which some large rock-slides of an exceedingly gradual character are going on." Nevertheless, the mountain is an object well worthy of study. It forms one side of a pass through the Blue Ridge, Chimney Rock forming the other. While the latter mountain is made up of smooth sheets of what appears to be gneiss, Bald Mountain is all over cracked and fissured, the fissures in some places forming large caves. The recent disturbances have chiefly affected a low spur of the mountain, rising about one thousand feet above the valley. From below the appearance is as if the whole side of the spur was sliding down.

Prof. Clarke first climbed up the side of this spur to a cave which had been discovered a very short time previously. Here he found himself below a precipitous mass of rock two or three hundred feet high, at the foot of which immense numbers of fallen bowlders had formed crevices and caves innumerable. But the new cave was the largest of all. The floor of the cave was everywhere covered with fallen rocks. The newspaper accounts tell of powerful "currents of ice-cold air" issuing from the caverns; but Prof. Clarke found no strong currents, and a difference of only four degrees of temperature between the inside and the outside air. The "smoke of the Bald Mountain volcano" is not smoke at all, but fine dust formed by the grinding and clashing of the rocks. Prof. Clarke next visited "the Crack," a crevice very probably of quite recent origin. This is merely a rent in the rock about one hundred feet in length, seventy-five in depth, and nowhere over ten in width. The explanation given of these cracks and the noises is found in the geological constitution of the mountain, which is built up of sheets of an easily decomposable gneiss, inclined at a slight angle and sliding downward. These sheets of gneiss are full of cracks running at approximately right angles to the pseudo-stratification. The caves are merely spaces which have been left when an upper sheet of rock has slidden off and become inclined against a lower. Nowhere is any sign of volcanic action to be seen. As for earthquakes, the surrounding country is as free from them as any other in the whole country. Prof. Clarke accounts as follows for the rumbling noises: The rocks, as we have seen, are cracked across their stratification. When a large sheet of gneiss is gradually sliding down, there comes eventually upon some part of it a strain sufficient to produce a fracture. This breaking is, of course, attended by a noise, to which the immense caves and crevices serve as resounding chambers.

Material Resources of European Russia.—Russia in Europe, considered with regard to its economic products, may be divided into five distinct zones or regions, viz.: Starting from the north, the tundras, the forest and agricultural regions (forming three