Page:Popular Science Monthly Volume 40.djvu/583

Rh merged coastal plain, and its margin as the true boundary between the continent and the ocean basin, or as the submerged continental margin. On the eastern coast the submarine plateau is trenched with submarine troughs running out from the mouths of the great rivers to the submerged continental margin and then opening into deep water. The best known of the channels are opposite the mouths of the Hudson and Delaware Rivers, Chesapeake Bay, and the Mississippi. Along the California coast the phenomena are different. The researches of Prof. Davidson have brought to light some twenty or more submarine channels on the coast from Cape Mendocino to San Diego, a distance of about seven hundred miles. But they have no obvious relation to existing rivers. They are not a submarine continuation of any system of river valleys on the adjacent land, but run in close to shore and abut against a bold coast, with mountains rising in some cases to three thousand feet within from three to five miles of the shore line, and wholly unbroken by any large river valleys. The channels of the Eastern coast are accounted for by supposing that they were always connected with the rivers opposite them, and that they have assumed their present positions by the operation of the changes of level to which the land has been subjected. But the disconnected positions of the Western channels can not be accounted for except as being the result of orogenic changes which have diverted the lower courses and places of emptying of the rivers since the channels were made. Prof. Le Conte's paper is devoted to the study of the nature and history of these changes.

Jupiter and the Comets.—Prof. 11. A. Newton showed, at the meeting of the British Association, that if a comet or other small body should pass in front of Jupiter, the kinetic energy of the planet would be increased by the gravitational attraction between the two bodies, while that of the comet would be diminished, and might be diminished to such an extent as to cause it to form (though possibly only temporarily) a member of the solar system. On the other hand, if a comet, already a member of the solar system, pass behind Jupiter, the kinetic energy of the planet will be diminished and that of the comet will be increased, and may conceivably be increased under favorable circumstances to such an extent that the comet may no longer remain a member of the system. The author had calculated that of one billion comets from space crossing, in all directions, a sphere equal in diameter to that of Jupiter's orbit, about twelve hundred would come near enough to Jupiter to have their period so much diminished as to be less than that of the planet.

The Baths of the Accursed.—Hammam Meskoutine, or the Baths of the Accursed, are a famous bathing-place and health resort not far from Constantino in Algeria. They are but a few minutes' walk from the railway station. The first object of interest within a quarter of a mile of the station is a superb hot waterfall, whence the vapors fly away abundantly. "Yet," says a writer who describes it, "it is not all of water. For the most part it is rigid, like a thing of ice. It is, in fact, mainly a petrifaction. The calcareous deposit in the hot spring above has incrusted the rocks, so that they have the corrugated appearance and something of the color of barley sugar. Here and there, over and between the still masses, there is an ooze or trickle of warm water, adding to the work already done. Grass and flowers grow well by the sides of this nutritious waterfall, though the whitened soil in the neighborhood does not seem adapted for vegetation of any kind. You climb to the level of the cascade, and then see, close by, a number of odd-looking cones and columns standing up from the blanched surface of the ground. The soil is hot to the hand, and you tread with an echo." The springs bubble up with a temperature of more than 200° Fahr. A litter of egg-shells and fowls' feathers by the edge of them tells of the purpose they serve to the residents of Meskoutine. Here the dinner is cooked, and the clothes are washed in one or another of the little basins by which the springs eddy up to the daylight. Though the Arabs give the baths an impolite name, and tell various weird tales about them, they love them well. The cones look like a procession of gigantic phantoms suddenly petrified. Some arc six or seven feet in height, and some are fourteen or fifteen feet. They mark the sites of