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Page:Popular Science Monthly Volume 44.djvu/442

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THE POPULAR SCIENCE MONTHLY.

obtain a specimen except through some fraud; and persons detected in defrauding the government of its cinnamon usually have to atone for the offense with their lives.

 

A Himalayan Landscape.—Mr. W. M. Conway, the Himalayan explorer, describes the view as an astonishing one which surrounds the traveler from Srinagar to Gilgit when he has emerged from the defiles which sunder the valley of Hunza Nagyr from Gilgit, and has climbed the vast ancient moraines near Tashot that form the final rampart of the fertile basin. "The bottom of the valley is, as usual, deeply furrowed by débris, the surface of which is covered by terraced fields, faced with Cyclopean masonry, and rich with growing crops and countless fruit trees. The mountains fling themselves aloft on either hand with astounding precipitousness, as it were, into the uppermost heights of heaven—so steeply, in fact, that a spring avalanche falling from the summit of Rakipershi on the south must almost reach the bottom of the valley. Rakipershi is 25,500 feet high; the Hunza peak is about 24,000 feet high. Their summits are separated by a distance of nineteen miles. Both mountains are visible from base to summit at one and the same time from the level floor of the valley between them, which is not more than 7,000 feet above the sea. No mountain view I saw in the Karakorums surpasses this for grim wonder of colossal scale, combined with savage grandeur of form and contrast of smiling foreground."

 

Composition of Clays.—The word clay, says Mr. Robert T. Hill, in his paper (United States Geological Survey) on the Clay Materials of the United States, has a diverse and elastic meaning. To the popular mind it is the familiar, gritless, plastic earth which is readily molded when wet. To the manufacturer it is the material he molds and bakes, which may be the natural plastic material of the popular mind, or a mixture of many ingredients either natural or artificial, according to the refinement of the ultimate product; this product varies as to simplicity of processes from the ordinary brick clays, which are natural mixtures of the essential sand and clay with iron and other accessories, to the washed, ground, screened, and compressed mixture of kaolin, feldspar, flint, and plastic clay from which the potter shapes china and porcelain into works of art. Clay material in nature is not always plastic, and many of the most valuable products are made from consolidated rock, as the Cornwall stone or rock kaolin, which is a crumbling granite. Many common brick clays are more like impure sand than clay, and some of these, from the earliest times, have been molded with straw to give them sufficient tenacity for the handling necessary before burning. Much of the aboriginal pottery of America is composed of various earths, with just enough clay to hold the particles together. The chief function of clay in the fictile arts is its partial fusion upon firing, and upon this and the skill of the artisan who fires the kiln depends the product, which is wonderfully varied by the mixtures of fluxes and tempering material. Plasticity is desirable for the handling of the unfired material. Nearly all unconsolidated or powdered material may be made to adhere by water and other ingredients than clay, so that it can be shaped for burning, but plastic clay is the cheapest natural material used for this purpose in all clay burning. The material for the coarse products occurs naturally, and is mixed with the non-plastic kaolins by the porcelain-maker to give the "clay" the necessary tenacity for handling and shaping.

 


NOTES.

An Experimental Study, by William O. Krohn, of simultaneous stimulations of the sense of touch, made upon ten different persons, among its interesting results showed that skin over the joints is much more sensitive than at other places; that touches on the back of the body are more distinctly felt, more clearly remembered, and therefore better localized than on the front part of the body; that the localizations are better for points not on the median line than for those on it; that they are not so correctly made on the left as on the right side of the body; that they are better on hairy portions than on those not covered with hairs; and that a difference in the power of correct localization exists between usually clothed and usually unclothed parts; the parts not covered, except in case of the joints, giving the more correct localizations.

By exposing hen's eggs to the vapors of alcohol for periods ranging from twenty-six to forty-eight hours, M. Ch. Féré has ascer-