is to this Class A that the experiments largely relate.

The experiments noted below were made with varying material, though the
principal type used was a fine sand, under the conditions in which it is
ordinarily found in excavations, with less than 40% voids and less than
10% of very fine material.

[Illustration: FIG. 7.]

_Experiment No. 2._--The first of these experiments, which in this
series will be called No. 2, was simple, and was made in order to show
that this material does not flow readily under ordinary conditions, when
not coupled with the discharge of water under high velocity. A bucket 12
in. in diameter, containing another bucket 9 in. in diameter, was used.
A 6 by 6-in. hole was cut in the bottom of the inner bucket. About 3 in.
of sand was first placed in the bottom of the larger bucket and it was
partly filled with water. The inside bucket was then given a false
bottom and partly filled with wet sand, resting on the sand in the
larger bucket. Both were filled with water, and the weight, _W_, Fig. 7,
on the arm was shifted until it balanced the weight of the inside bucket
in the water, the distance of the weight, _W_, from the pivot being
noted. The false bottom was then removed and the inside bucket, resting
on the sand in the larger one, was partly filled with sand and both were
filled with water, the conditions at the point of weighing being exactly
the same, except that the false bottom was removed, leaving the sand in
contact through the 6 by 6-in. opening. It is readily seen that, if the
sand had possessed the aqueous properties sometimes attributed to sand
under water, that in the inside bucket would have flowed out through the
square hole in the bottom, allowing it to be lifted by any weight in
excess of the actual weight of the bucket, less its buoyancy, as would