| 摘要 |
The invention relates to a long rule/level. It consists of a profiled section containing a coloured liquid 1 and comprising a transparent window 5 at each end. Levelling is obtained when the liquid is stabilised at the reference mark 4 drawn on the mirror 3 which is inclined at 45 DEG . The rule according to the invention is in particular intended for regulation over a great length. <IMAGE>
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