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A cathetometer is an instrument for measuring vertical distances in cases where a scale cannot be placed very close to the points whose distance apart is desired.
The instrument consists essentially of an accurately graduated scale and a horizontal
''A Handbook of Physics Measurements''
by E. S. Ferry, 1914, volume 1 Among the uses of a cathetometer is reading the levels of a liquid in a capillary tube, such as in measurements of
A cathetometer is an instrument for measuring vertical distances in cases where a scale cannot be placed very close to the points whose distance apart is desired.
The instrument consists essentially of an accurately graduated scale and a horizontal telescope
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...
capable of being moved up and down a rigid vertical column. The position of the telescope can be read by means of an attached Vernier scale
A vernier scale, named after Pierre Vernier, is a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation, thereby increasing resolution and reducing measurement unc ...
. In measuring the vertical distance between two points, the instrument must first be leveled. Next, the cross hair in the eyepiece of the horizontal telescope is brought into coincidence with the image of one point and the position of the telescope noted; the cross hair is then brought into coincidence with the image of the other point and the new position of the telescope noted. The difference between these readings is the vertical distance required.This text is copied fro''A Handbook of Physics Measurements''
by E. S. Ferry, 1914, volume 1 Among the uses of a cathetometer is reading the levels of a liquid in a capillary tube, such as in measurements of
surface tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to f ...
. A cathetometer also can be used for following the changes in liquid level in a dilatometer
A dilatometer is a scientific instrument that measures volume changes caused by a physical or chemical process. A familiar application of a dilatometer is the mercury-in-glass thermometer, in which the change in volume of the liquid column is ...
due to, for example, a chemical reaction therein.
See also
* Travelling microscopeReferences
{{Reflist Length, distance, or range measuring devices Optical instruments