| 摘要 |
<p>The line-drawing instrument fits on a drawing-board ruler, enabling lines to be quickly drawn without prior marking out. It comprises a number of parts working together to allow the ruler to be indexed, the indexing distance being steplessly adjustable. Two parts (1, 2) are secured together by a screw (6) and fit in a guide (3), in which they have are movable in two directions (a, b) in opposition to springs (4, 5). Distance (a) is adjustable by screw (6) against a scale (8). For drawing lines, downwards pressure is applied at point (e) onto the paper to fix in position. The parts then form, with edge (9) a stop for the ruler which is moved against spring action (4) against the stop and secured, the parts being then released to return to the rest position. The latter are rubber-coated on the underside to prevent slippage.</p> |
