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Related to Caliper: micrometer caliper


(US), caliper
1. an instrument for measuring internal or external dimensions, consisting of two steel legs hinged together
2. Med a splint consisting of two metal rods with straps attached, for supporting or exerting tension on the leg
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a device that is lowered into a bore hole on a cable to determine the diameter of the hole. Mechanical and ultrasonic calipers are used.

The most commonly used mechanical caliper consists of three or four lever feelers (probes), which are pressed against the walls of the bore hole by springs, and a rheostat whose sliding contact is connected to the feelers by means of pushrods. A change in the diameter of the borehole produces a proportional change in the resistance of the rheostat. This resistance is measured on the surface and, as a result, a curve is produced showing the change in the diameter of the borehole from the face to the mouth of the hole. Recent models are equipped with a controlled lever device that can be opened and closed repeatedly on command from the surface.

An ultrasonic caliper is a hydrolocating device with two directional electroacoustic transducers located on opposite sides of the borehole instrument. Each transducer operates alternately as an ultrasonic oscillation emitter and detector. The time interval between the moments of the transducer’s emission and its reception of the ultrasonic pulse reflected from the wall of the borehole is measured on the surface. Since the interval is proportional to the distance from the device to the borehole wall, two longitudinal profiles of the borehole are produced, characterizing its diameter.

Since the cross section of a borehole is usually noncircular, instruments have been developed that permit measurement of the size and shape of the cross section.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


(design engineering)
An instrument with two legs or jaws that can be adjusted for measuring linear dimensions, thickness, or diameter.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


An instrument, resembling a pair of dividers, with adjustable legs for measuring the diameter or the thickness of bodies. Also see inside caliper and outside caliper.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
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