When a wheel rolls along on a soft ground (S.G.) such as a sandy land or a marshland, the resistance which the wheel receives from the ground generally differs from that in the case of a hard ground, Experiments in this connection was made, using a wooden circular cylinder as the wheel to simplify the problem and also to have the reproducibility of measuring results. For the soft ground, a sand bed was used. To measure the resultant resistance received by the wheel, its direction θ, etc., the vertical and horisontal components of R, i.e. V and H, were measured separately by an electrical means. To approximate the soft ground of sand to a real ground as far as possible, its surface was formed into sinusoidal wave for the measurements of running resistance of a wheel.

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