抄録
A new measuring method was obtained for the inner radii of cylinder. The time intervals were measured for two similar rams which properly fit the cylinder to be measured but are minutely different in radius and descend along the inner surface of the cylinder. The form of the rams was studied so as to make it possible to measure the inner radii at any height of the cylinder. The authors confirmed that the results by this new method coincide considerably well with those obtained by ordinary metrological ones and accordingly it can be widely applied to the precise measurement of the inner radii of a cylinder.
