Fig. 80.
Filters.—Two barrels ([Fig. 80]), one inside the other, having a space of from 4 to 6 inches clear all round between them filled with layers of gravel, sand, and charcoal, form an excellent filter. The inside one, without a bottom, rests on three stones placed in layers of sand, charcoal, and coarse gravel. The water flows into the space between the barrels and forces its way through the gravel, charcoal, and sand into the inner barrel. Or they may be placed as in [Fig. 81] and connected by a pipe.
Fig. 81.
If the water is from a small spring gushing up out of the earth, perforate the bottom of the outer barrel with a number of holes, and leave the bottom to the inner barrel, which should be pierced with holes round its sides near the top.
In both these filters draw off the water by a pipe running through the outer into the inner barrel.
Allow eight pints per man in hot and six in temperate climates for cooking and drinking, and a similar amount for washing. In stationary camps allow 5 gallons per man for all purposes.
LOG HUTS.
Good huts to last for years are quickly made of logs placed one over the other, being notched half their respective thicknesses at the angles so as to fit one into the other. Moss is driven into the interstices. A roof is put on of split logs, gouged out in the centre, so that each is like a long curved gutter. A layer of these is placed side by side, with the hollow side uppermost, one end resting on the ridge-pole, the other on the walls. A second layer is put over them with the hollow side down. A large split log, well hollowed out, is used as a ridge-piece. Cowdung mixed with water and well plastered over mud walls or floors renders them hard, tough, and less subject to injury from weather. A thin coating of this applied every day to the earthen floors of huts adds much to the appearance of cleanliness.