| 摘要 |
PURPOSE:To perform centripetal operation rapidly and accurately by providing a pedestal having a special construction, a centripetal board and a plumb bob. CONSTITUTION:The pedestal 1 is provided at a position so that a water pile 41 is located almost at the center of a hole for centripetalizing and legs 13 are pushed in the ground 5 and fixed horizontally. A centripetal board 2 is placed on the pedestal 1 so that the center of a hole for fixing almost coincides with the center of the hole for centripetalizing provided to the pedestal 1. Then, the plumb bob 3 is suspended with a string from a suspending reference point provided in a space above a fixed device and the tip of the plumb bob 3 is thrust out downward from a hole 21 for fixing provided to the centripetal board 2 and the hole 11 for centripetalizing provided to the pedestal 1 and the position of a suspending reference point is adjusted and centripetalized so that the tip of the plumb bob 3 is located right above a central nail. The operation to this point is performed in a calm. Then, the plumb bob 3 is pulled down and connected with the centripetal board 2. By doing in this way, the plumb bob 3 is placed on the pedestal 1 with the weight added with the weight of the centripetal board 2 and at the same time, the string suspending the plumb bob 3 is stretched with the fixed tensile force.
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