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Rh old straw is highly prized as fertilizer for the fields on which it is grown, or it may serve as fuel, the ashes only going to the fields.

Burned clay tile, especially for the cities and public buildings, are very extensively used for roofing, clay being abundant and near at hand. In Chihli and in Manchuria millet and sorghum stems, used alone or plastered, as in Fig. 88, with a mud mortar, sometimes mixed with lime, cover the roofs of vast numbers of the dwellings outside the larger cities.

Fig. 88.—Millet-thatched roofs plastered with earth: mud chimneys; walls of houses plastered with mud, and winter storage pits for vegetables built of clay and chaff mortar.

At Chiao Tou in Manchuria we saw the building of the thatched millet roofs and the use of kaoliang stems as lumber. Rafters were set in the usual way and covered with a layer about two inches thick of the long kaoliang stems stripped of their leaves and tops. These were tied together and to the rafters with twine, thus forming a sort of matting. A layer of thin clay mortar was then spread over the surface and well trowelled until it began to show on the under side. Over this was applied a thatch of small millet stems bound in bundles eight inches thick, cut