Procure an inner tube of a bicycle tire, the closed-end kind, and fold it in four alternate sections, as shown in Fig. 1. Cut or tear a piece of cloth into strips about 1/2 in. wide, and knot together. Fasten this long strip of cloth to the folded tube and weave it alternately in and out, having each run of the cloth about 4 in. apart, until it is bound as shown in Fig. 1.

Illustration: Fig. 1, Fig. 2 -- Inner Tube and Cover

Make a case of canvas that will snugly fit the folded tube when inflated. The straps that hold the preserver to the body may be made of old suspender straps. They are sewed to the case at one end and fastened at the other with clasps such as used on overall straps. The tube can be easily inflated by blowing into the valve, at the same time holding the valve stem down with the teeth. The finished preserver is shown in Fig. 2.