Without such a box, the sediment will be carried into and may clog the drain.

The box is to be emptied occasionally, before the sediment overflows.
[Illustration: Fig.221.Power Grindstone.] In order that the tool may be ground accurately, there are various devices for holding it firmly and steadily against the stone.

A good one is shown in Figs.

221 and 222.

This device is constructed as follows: A board A is made 2" thick, 6" wide, and long enough when in position to reach from the floor to a point above the level of the top of the stone.