THE POPULAR SCIENCE MONTHLY.
ascent is enough to wear out a pair of shoes. The snow is rarely more than a few feet deep, but is cut up on the surface into numberless rough, wedge-shaped teeth, and is constantly dissolved at the bottom by the warm ashes beneath it. "Nothing like crevasses occur in the snow, and the yawning chasms reported by travelers or would-be travelers can be set down as purely imaginary." The approach to the crater was signalized by a strong odor of hydrogen sulphide that filled the air. The crater is about two thousand by thirteen hundred feet in diameter, and from eight hundred to fifteen hundred feet in depth, with nearly perpendicular walls from which jets of steam come hissing and sizzling, and rocks of various sizes are continually falling and plunging with a roar to the bottom. This bottom is heaped unevenly with débris of various sorts and colors; and, as Mr. Farrington had to look down into it with a wind so fierce that it caused the very walls to tremble, its aspect was dismal enough. There is none of the heat and movement usually associated with volcanic eruptions, for that phenomenon here is very mild indeed. Various parts of the crater rim have been named the Pico Mayor, or highest point; El Portezuelo, or Little Door; El Espinazo del Diablo, or Devil's Backbone; and El Malacate, the windlass, where the sulphur gatherers are let down. The layers of lava of which the walls of the crater are made are plainly visible at intervals, dipping at various angles.
A New Theory of Geyser Formation.—At a recent meeting of the Physical Society at Eton College, Prof. T. C. Porter discussed a new theory of geyser formation, which is reported as follows in the Chemical News: "The theories of Bunsen and others fail to explain why the geyser throat appears almost completely full at the end of an eruption. This immediate refilling is the more remarkable when it is remembered that some of the geysers of the Yellowstone region discharge a million and a half gallons at each eruption, and that the eruptions may occur at five minute intervals. Moreover, the theories generally accepted assume steeper temperature gradients than those in a region like Yellowstoue. Professor Porter suggests that the phenomena are better explained on the assumption of an arrangement of strata such as exists in artesian-well districts; the throat or shaft of the geyser being in the position of a well communicating with a subterranean stream—the 'tube' of the geyser. From the disturbed nature of the region, the tube of the geyser follows a waved course. The 'shaft' rises from the crest of the terminal wave; the other crests may be steam traps. Since a basinlike formation is characteristic of all geyser regions, it is fair to assume that the end of the tube remote from the shaft has an outcrop in the hills that form the sides of the basin. By means of this outcrop, water continually flows into the tube. Where the tube does not sink deeply enough to attain the temperature necessary for the generation of steam, a quietly flowing hot spring is the result. But if at any point the tube descends to underground temperatures sufficiently great, steam is formed, and is trapped at the highest point of a bend. Ultimately this steam checks the flow of water, until the accumulated head of cool water from the hills overcomes the resistance, condenses the steam, and re-establishes liquid continuity. Urged by the pressure behind it, the steam is impelled toward the geyser throat; it forces the hot water before it until equilibrium is once again restored in the tube."
Materials for Paper Making.—One of the most important considerations in the selection of materials for paper making is that of the structure of the fiber. The most perfect spinning fibers, and the best for paper making, are cotton and flax. They differ in that cotton—unique in that respect—occurs in the form of ultimate fibers and is a spinning unit, while flax is composite, or a bundle of ultimate fibers or spinning units. Next to flax are rhea, inferior on account of the irregularity of its fibers; hemp and jute, which have distinct qualities. After these are the fibers used in twine and rope making, but not adapted for spinning. All may be used in paper making, with various results in the quality of the product. Another important item bearing upon paper material is the chemical composition of the fiber, or its capacity of resistance to the natural agencies of destruction. This is the living question in modern paper making. In this point cot-