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An instrument for measuring small differences in height, for example, between two columns of mercury.



an instrument for measuring a vertical distance between two points, which need not be situated along the same vertical. A cathetometer consists of a rod mounted vertically with the aid of a level and three leveling screws; a horizontally placed telescopic tube, which can be moved along the rod while remaining perpendicular to it; and a device for the accurate aiming of the tube. The eyepiece of the cathetometertube is equipped with crosshairs. In using a cathetometer thecrosshairs are successively aimed at each of the selected points, and the unknown distance is determined by the displacementshown on a scale on the cathetometer’s rod. The cathetometerwas invented by the French physicists P. Dulong and A. Petit(1816); various improvements in its construction were con-tributed by D. I. Mendeleev.

References in periodicals archive ?
While these values for the standard deviations between each step are quite close, the standard deviation between time steps in consecutive runs at the lower temperatures were generally greater because it is more difficult to measure the passage of the meniscus with the cathetometer when the meniscus moves slowly.
It was possible to measure the initial and final crack lengths adequately using an optical cathetometer positioned over an x-y micrometer table.
The climbing height of the fluid was then measured using a cathetometer (Gaertner Scientific Co.
1) [degrees] C and the decrease of the meniscus in the capillary was measured using a cathetometer.