Broken line drawing aid - uses straight edge with serrated upper surface to guide pen

摘要

The drawing of dotted or dashed lines with a uniform spacing is facilitated by a special straight edge (1) and pen (3). The straight edge (1) consists of a base (2) with a dove-tail groove to receive a bar (5) which is fixed by screws (6). The upper face of the bar (5) has a line of equally spaced transverse ridges (7). The pen (3) has a short side-ways projecting arm which lifts the nib clear of the paper when passing over a ridge and so produces a dashed line with equally spaced dashes of uniform length.