Page:Popular Science Monthly Volume 49.djvu/879

Rh  Description of a New Genus and Three New Species of Crustaceans from an Artesian Well at San Marcos, Texas.—1088. Description of a New Genus and Species of Blind Tailed Batrachian from the Subterranean Waters of Texas.—1089. Description of a New Stickleback from the Coast of Maine.—1090. Description of a New Species of Ant Thrush from Nicaragua.—1091. Partial List of Birds collected at Altamira, Mexico, by F. B. Armstrong.—1092. On Some Prepared Parasitic Hymenopterous Insects from Ceylon.—1093. An Annotated List of Birds observed on Margarita Island and at Guanta and Laguayra, Venezuela.—1094. List of Coleoptera collected on the Tana River and on the Jomboul Range, East Africa.

Taber, C. A. M. The Coming Ice Age. Boston: George H. Ellis. Pp. 94.

Tilden, J. H. Cursed before Birth. Denver, Col.: (Author). Pp. 314.

White, E. E. A School Algebra. New York: American Book Company. Pp. 394. $1.

Wilson, Dr. Erastus. La Enseñanza Moderno (Modern Education). Article 24. Summary of the Papers in the Annals of the Institute of Secondary Instruction of Havana. Havana: Military Printing Office. Pp. 14. Distributed.



A New Classification of Elevation Areas,—Prof. Hermann Wagner, of Göttingen, one of the best-known geographers and statisticians of Germany, has recently published a new

altitude classification of the earth's surface, which he divides into five regions, as follows: The culminating area of the earth's crust, occupying six per cent of the surface and lying altogether above 1,000 metres, with a mean height of 2,200 metres (or 7,200 feet) above the sea. The continental plateau, occupying all the surface from the 1,000 metre contour line of elevation to the 200 metre contour line of depth—i. e., to the margin of the shallow sea border or continental shelf; it comprises 28·3 per cent of the surface, and has a mean elevation of 250 metres (800 feet) above the sea. The continental slope, from a depth of 200 metres to 2,300 below sea level, covers nine per cent of the earth's surface, and has a mean depth of 1,300 metres (4,300 feet). The oceanic plateau, between the depths of 2,300 and 5,000 metres, occupies no less than 57·3 per cent of the surface, and has a mean depth of 4,100 metres (13,500 feet). Finally, the depressed area, deeper than 5,000 metres, is assumed to occupy three per cent of the surface, with a mean depth of 6,000 metres (say 20,000 feet). The mean level of the surface of the earth's crust is placed by these calculations at a depth of 2,300 metres, or 7,500 feet, below actual sea level. The total area of land is worked out at 28·3 per cent and that of sea at 71·7 per cent of the earth's surface; the ratio of land to water surface is thus 1: 2·54. The accompanying chart is reproduced from Nature of June 4th.

Silk from Wood.—According to the London Times, there is growing up in France a considerable industry, based on the manufacture of a so-called silk from wood pulp.