The dot nearest the width (measured in inches) gives the B.M.for lumber 1" thick.
The _try-square_, Fig.

200, which is most commonly used for measuring the accuracy of right angles, is also convenient for testing the width of a board at various places along its length, for making short measurements, and as a guide in laying out lines with a pencil or knife at right angles to a surface or edge.

The sizes are various and are indicated by the length of the blade.

A convenient size for the individual bench and for ordinary use has a blade 6" long.

It is also well to have in the shop one large one with a 12" blade.
[Illustration: Fig.203.Using the Try-Square.] [Illustration: Fig.204.Scribing with Knife by Try-Square.] In testing the squareness of work with the try-square, care must be taken to see that the head rests firmly against the surface from which the test is made, and then slipped down till the blade touches the edge being tested, Fig.203.The edge should be tested at a number of places in the same way: that is, it should not be slid along the piece.