Casthetometer

A measuring instrument that precisely measures the difference in height between two points on a vertical line from a distance of more than 1 m. A length scale is attached to a vertical metal pillar. A telescope that moves up and down along this pillar is attached horizontally, and the pillar is made correctly vertical using the attached spirit level and adjustment screw, and the telescope is adjusted to be perpendicular to it. The point to be measured is aligned with the crosshairs of the telescope, and its height is read using the main scale of the pillar and the attached vernier scale. Next, the telescope is raised and lowered, aligned to another point, and the height is read to determine the difference from the previous point. The main scale of the pillar is available as long as 1 m, and it can measure to within 0.01 mm.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

1 m 以上離れた距離から，鉛直線上の2点の高さの差を精密に測る測定器．鉛直に立つ金属製の柱に長さの目盛がつけてある．この柱にそって上下する望遠鏡を水平に取り付け，付属の水準器と調節ねじにより柱を正しく鉛直にし，望遠鏡はこれと直角に調節する．測定しようとする点を望遠鏡の十字線に合わせ，その高さを柱の主尺と付属の副尺を用いて読む．次に望遠鏡を上下して，ほかの点に合わせてその高さを読んで前との差を求める．柱の主尺は1 m のものがある．0.01 mm まで測定ができる．

出典　森北出版「化学辞典（第2版）」化学辞典 第2版について　情報