From the above experiment it may be concluded, that it is extremely
difficult to thrust sand out of a tube by means of a fitting plug or
piston; and this, upon trial, is found to be the case. Fit a piston to
a tube (exactly like a boy’s pop-gun), pour some sand in, and try with
the utmost strength of the arm to push out the sand. It will be found
impossible to do this: rather than the sand should be shot out, the
tube will burst at the sides.