A larger cask mounted on the after wheels of a waggon, and fitted with chocks on a frame lying on the axle is useful.
Camp filter.
Filtering bags can be made of woollen or other cloth. An excellent and convenient camp filter is thus made: Take a wooden box or barrel, long and deep. Bore a number of holes in the bottom, fasten in a blanket bag, and then place a layer of grass, small twigs, or moss on the bottom, over the holes; then a layer of sand; then a thick bed of coarse lumps of charcoal; then fresh layers of grass or moss, until the box or barrel is about half filled. Then fashion a false head or cover, making it just large enough to move up and down the cask or box freely; burn or bore a number of holes in it, and, when fitted in, press it firmly down on the arrangement below, and drive a few nails in above to keep it from rising. When this contrivance is partially sunk in a pond or lake the water will ascend to the upper compartment above the false head, from which it can be dipped or drawn for use.
Another useful barrel filter can be made by knocking both the heads out of a small cask, boring it full of gimlet holes, placing it on a thick layer of charcoal and pebbles in a larger cask, also bored full of holes, and then filling in all the space between the outer and inner barrels with the mixture, as shown in the above illustration.
The following is an expedient easily extemporised and frequently used in damp soils, where water is scarce. A quantity of grass is tied up in a wisp, or plaited into a bag; two reeds are inserted in this—one as a suction tube, and the other to admit air; and the apparatus is buried wherever a sufficiency of moisture is likely to permeate the soil.