, the cohesive forces are practically negligible for walls, say, 10 ft. high, especially if the earth surface is level. In fact, a little examination of the original drawings showed, for walls about 6 ft. high, that the earth thrust, neglecting cohesion, was only from 1 to 5% in excess over that for
. The smaller percentages referring to
, or
, while the larger percentages referred to
, for earth surface horizontal or sloping at the angle of repose.