Dimensions. The various dimensions of an object represented are shown on the drawing by appropriate figures, which express feet when followed by ', and inches when followed by ". Thus 2' should be read as two feet, and 2" as two inches. 12' 7 3/4" is the same as twelve feet and seven and three-quarters inches.

The figures always show the dimensions of the thing represented; they do not agree with the dimensions of the drawing except when the latter is full-sized. See dimension figures in Fig. 23.

Fig. 22

Half Size.

Dimension Lines

Dimension figures are always placed on, or near, lines along which they apply. In drawings these lines are usually in color (red), but may be dotted black, as in Fig. 23. When convenient, they are placed within the outline of the drawing; but if the drawing is small or crowded, they are placed at one side, and are connected with the parts they limit by perpendicular, colored or dotted lines. Two arrow-heads, one on each side of the dimension figure, locate the points between which it applies. Several dimensions may be given on the same line, each being limited by its own arrow-heads.