wood as in measuring metal, but
still there is a considerable variety of tools for this purpose.

[Illustration: Fig. 186. Inserting a Bit in Stock.]

[Illustration: Fig. 187. Hand-Drill.]

[Illustration: Fig. 188. Screwdriver.]

[Illustration: Fig. 189. Screwdriver-Bit.]

[Illustration: Fig. 190. Spiral Screwdriver.]

For measuring distances, the _rule_, Fig. 191, is the one in most
common use. It is usually made of boxwood. For convenience it is
hinged so as to fold. A rule is called "two-fold" when it is made of
two pieces, "four-fold" when made of four pieces, etc. When measuring
or marking from it, it can be used more accurately by turning it on
edge, so that the lines of the graduations may come directly against
the work. The one in most common use in school shops, is a two-foot,
two-fold rule. Some instructors prefer to have pupils use a four-fold
rule, because that is the form commonly used in the woodworking
trades. Steel bench-rules, Fig. 192, are satisfactory in school work
because unbreakable and because they do not disappear so rapidly as
pocket rules. They need to be burnished occasionally.

[Illustration: Fig. 191. Two-Foot Rule. Two Fold.]

[Illustration: Fig. 192. Steel Bench-Rule.]

[Illustration: Fig. 193. Back of Steel Square, Brace Measure.]

The _steel square_, Figs. 193, 194, 196, 197, is useful, not only as a
straight-edge and try-square, but also for a number of graduations and
tables which are stamped on it. There are various forms, but the
one in most common use consists of a blade or "body" 24"x2" and a
"tongue," 16"x1-1/2", at right angles to each other. Sargent's trade
number for this form is 100. It includes graduations in hundredths,
thirty-seconds, sixteenths, twelfths, tenths, and eighths of an
inch, also a brace-measure, an eight-square measure, and the Essex
board-measure. Another style, instead of an Essex board-measure, and
the hundredths graduation has a rafter-table. The side upon which the
name of the maker is stamped, is called the "face," and the reverse
side the "back."

The brace-measure is to be found along the center of the back of the
tongue, Fig. 193. It is used thus: the two equal numbers set one above
the other represent the sides of a square, and the single number to
their right, represents in inches and decimals, the diagonal of that
square. E. g., 54/54 76.37 means that a square the sides of which are
54" would have a diagonal of 76.37".

For determin