| 摘要 |
The compasses consist of two legs 1 and 5 set one on top of the other with the axes coinciding at point 12. The leg 5 supports the drawing instrument holding mechanism 6, whose clamping device is directed towards the leg 1; and the part 7 which receives the protuberance 8 on the pointed rod 2 in order to define the desired spacing between the legs 1 and 5. The shorter leg 1 supports the pointed rod 2, whose length is approximately that of the compasses; the device 3 by which the pointed rod 2 is held; and the part 9 on its flank which keeps the leg 1 parallel with the blackboard while an angle is being drawn. The mechanism 3 by which the pointed rod is held comprises a part having a reference mark intended to be brought opposite the selected reference mark on the pointed rod. The pointed rod, the three axes 12, 13, 14 and the part 7 lock the compasses together when they are being carried about. <IMAGE>
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