the horizontal force, less the resistance of the carriage wheels, we have,[Footnote 5] ]
The value of
was found by weighing: For the dry sand it varied from 0.79 to 0.65, for heights of the sand in the box varying from 1.2 to 3.5 in. For the damp sand and fresh earth (slightly moistened and slightly rammed) which can stand with a vertical face for the height of the box, the filling was loosened by many blows on the box, and
was taken equal to 1.
Three suppositions were made: (1) that both cohesion and friction acted at the same time before motion; (2) that friction alone acted (
