| 摘要 |
PROBLEM TO BE SOLVED: To enhance the efficiency of work using a plumb bob 10. SOLUTION: The plumb bob 10 is provided with three or more supporting legs 15 radially placed with the axis 11s of a dead weight 11 as a center. An indicating part 12 is contacted to a target point P1 from an upper direction, and the tensile force of plumb line 14 is released. Then the dead weight 11 is tilted with the indicating point 12 as a fulcrum, and at least the pointing parts of two supporting legs 15 are landed at the vicinity of the target point P1.
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