the hole filled with a plug,
or, where the wood is to be painted, with putty. They are used for
interior finishing and other nice work.

[Illustration: Fig. 227. Tack.]

_Tacks_, Fig. 227, vary in size and shape according to their use; as,
flat-headed, gimp, round-headed, and double-pointed or matting tacks,
a sort of small staple. Their size is indicated by the word "ounce."
For example, a two-ounce tack is 1/4" long, a three-ounce tack is 3/8"
long, a four-ounce tack is 7/16" long, a six-ounce tack is 1/2" long,
etc. This term once meant the number of ounces of iron required to
make 1000 tacks.

Tacks are useful only in fastening to wood thin material, such as
veneers, textiles, leather, matting, tin, etc. Tinner's tacks, which
are used for clinching, are commonly called clinch-nails. Wire tacks,
altho made, are not so successful as cut tacks because they lack a
sharp point, which is essential.

[Illustration: Fig. 228. Corrugated Fastener.]

_Corrugated fasteners_, Fig. 228, or fluted nails, are used to fasten
together two pieces of wood by driving the fastener so that one-half
of it will be on each side of the joint. Their size is indicated by
the length and the number of corrugations, as 1/2", four. They are
often useful where nails are impracticable.

_Glaziers' points_ are small, triangular pieces of zinc, used to
fasten glass into sashes.

SCREWS

(a) _Wood-screws_, Fig. 229, may be classified by the material of
which they are made; as, steel or brass. Steel screws may be either
bright,--the common finish,--blued by heat or acid to hinder rusting,
tinned, or bronzed. Brass screws are essential wherever rust would be
detrimental, as in boats.

(b) Screws are also classified by shape; as, flat-headed,
round-headed, fillister-headed, oval-countersunk-headed, and
square-headed screws. Flat-heads are most commonly used. There are
also special shapes for particular purposes. Round-heads may be used
either for decoration or where great drawing power is desirable. In
the latter case, washers are commonly inserted under the heads
to prevent them from sinking into the wood. Oval-heads are used
decoratively, the head filling the countersunk hole, as with
flat-heads, and projecting a trifle besides. They are much used in
the interior finish of railway cars. They are suitable for the strap
hinges of a chest.

The thread of the screw begins in a fine point so that it may
penetrate the wood easily where no hol