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.