| 摘要 |
1,218,659. Identifying a surface by radiation. GOETZEWERKE FRIEDRICH GOETZE A.G. April 30, 1968 [May 20, 1967], No. 20503/68. Heading G1A. The upper surface of a piston ring is marked with paint, magnetic particles, or radio-active material and is detected by a sensing device moving relative to it. The position of the upper surface of a ring in a packet may be checked by a Geiger counter. Radio-active sources are exemplified. |
