抄録
When a completely polished surface plate is placed face down on the completely leveled plane and a slight force is applied at a corner point of it in a direction parallel to the side continuous thereto, the theoretical pivoting center of the surface plate is unique to a given shape thereof. The present method proposes to judge the flatness of a surface plate by a deviation between its theoretical pivoting center and an actual measurement. The theoretical pivoting center was calculated for surface plates of various shapes for this study. In the experiment an appropriate amount of grease was sandwiched between a surface plate and the level plate to create as completely flat planes as possible. In this condition the pivoting centers of surface plates nearly coincided with the calculated points. In the case of semi-polished surface plates, approximate wavy shapes of surface could be predicted from measurements of their pivoting points.
