e revolving stone, to hold the tool at a fixed angle
which may be adjusted, and to press the tool against the stone with
considerable pressure. The wheel should revolve toward the edge
which is being ground, for two reasons. It is easier to hold the tool
steadily thus, and the danger of producing a wire edge is lessened.
The edge as it becomes thin, tends to spring away from the stone and
this tendency is aggravated if the stone revolves away from the edge.
If the stone does not run true and there is a consequent danger of
digging into the stone with the tool which is being sharpened, the
stone would better revolve away from the edge. The grinding should
continue until the ground surface reaches the cutting edge and there
is no bright line left along the edge. If the grinding is continued
beyond this point, nothing is gained, and a heavy wire edge will be
formed.

A very convenient and inexpensive grinding tool, Fig. 224, sold as
the "_Agacite grinder_,"[7] has a number of different shaped grinding
stones made chiefly of carborundum.

The _oilstone_. After grinding, edge tools need whetting. This is done
on the whetstone, or oilstone. The best natural stones are found near
Hot Springs, Arkansas. The fine white ones are called Arkansas
stones, and the coarser ones Washita stones. The latter are better for
ordinary woodworking tools. The _India oilstone_, an artificial stone,
Fig. 77, p. 58, cuts even more quickly than the natural stones. It is
made in several grades of coarseness. The medium grade is recommended
for ordinary shop use. Oil is used on oilstones for the same purpose
as water on a grindstone. When an oilstone becomes hollow or uneven by
use, it may be trued by rubbing it on a flat board covered with sharp
sand, or on sandpaper tacked over a block of wood.

[Illustration: Fig. 225. Slipstone.]

_Slipstones_, Fig. 225, are small oilstones, made into various
shapes in order to fit different tools, as gouges, the bits of
molding-planes, etc.

_Files_ are used for sharpening saws, augers, scrapers, etc. See
above, p. 90.

9. CLEANING TOOLS.

The _bench duster_. One may be noted hanging on the bench shown
in Fig. 166, p. 98. Bristle brushes for cleaning the benches are
essential if the shop is to be kept tidy.

_Buffer._ Wherever a lathe or other convenient revolving shaft is
available, a buffer made of many thicknesses of cotton cloth is very
valuable for polishing tools. The addition of a little tri