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THE POPULAR SCIENCE MONTHLY.

ger of departing from the highway when in one of these deep cuts; after scrambling for miles along the broken loess above the road, he only regained it when a further passage was cut off by a precipice on the one side, while a jump of some thirty feet into the beaten track was his only alternative upon the other.

Difficult as may be such a territory for roads and the purposes of trade, its advantages to a farmer are manifold. Wherever this deposit extends, there the husbandman has an assured harvest two and even three times in a year. It is easily worked, exceedingly fertile, and submits to constant tillage, with no other manure than a sprinkling of its own loam dug from the nearest bank. But loess performs still another service to its inhabitants. Caves made at the bases of its straight clefts afford homes to millions of people in the northern provinces. Choosing an escarpment where the consistency of the earth is greatest, the natives cut for themselves rooms and houses, whose partition-walls, cement, beds, and furniture are made in toto from the same loess. Whole villages cluster together in a series of adjoining or superimposed chambers, some of which pierce the soil to a depth of often more than two hundred feet. In costlier dwellings the terrace or succession of terraces thus perforated are faced with brick, as well as the arching of rooms within. The advantages of such habitations consist as well in imperviousness to changes of temperature without as in their durability when constructed in properly selected places—many loess dwellings outlasting six or seven generations. The capabilities of defense in a country such as this, where an invading army must inevitably become lost in the tangle of interlacing ways, and where the defenders may always remain concealed, are very suggestive.

There remains, lastly, a peculiar property of loess which is perhaps more important than all other features when measured by its man-serving efficiency. This is the manner in which it brings forth crops without the aid of manure. From a period more than two thousand years before Christ, to the present day, the province of Shansi has borne the name of "Granary of the Empire," while its fertile soil, hwang-tu, or "yellow earth," is the origin of the imperial color. Spite of this productiveness, which, in the fourteenth century, caused Friar Odoric to admiringly call it "the second country in the world," its present capacity for raising crops seems to be as great as ever. In the nature of this substance lies the reason for this apparently inexhaustible fecundity. Its remarkably porous structure must, indeed, cause it to absorb the gases necessary to plant-life to a much greater degree than other soils, but the stable production of those mineral substances needful to the yearly succession of crops is in the ground itself. The salts contained more or less in solution at the water-level of the region are freed by the capillary action of the loess when rainwater sinks through the spongy mass from above. Surface moisture, following the downward direction of the tiny loess-tubes, establishes a