| 摘要 |
A parallel rule comprising two rulers 1, 2 linked by at least two equal-length cross-arms 4, the cross-arms 4 being of asymmetrical shape such that the cross-arms 4 interfere to the minimum extent with the holes or knobs 3 which are used to move the rulers 1, 2. The device is of particular utility as a compact parallel rule or plotter suitable for small plotting tables.
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