Browse Items (54 total)

circular protractor.JPG
A mathematical instrument for laying down and measuring angles on paper, used in drawing or plotting.

An optical instrument used to measure angles in surveying, meteorology, and navigation. The earliest theodolite consisted of a small mounted telescope that rotated horizontally and vertically. Washington and Lee taught surveying in the mid-19th…

An instrument with a movable pointer used for mechanical measurements of the area of an (irregular) plane figure.


Buoyancy of Air.JPG
Chemists, and other people who do careful weighings, know that we live at the bottom of a sea of air, and that a buoyant force equal to the weight of the air displaced by our bodies acts upward on us. Alas, the density of air is small, and the…


A sextant is used in nautical navigation measure the angle between two visible objects. The angle, and the time it was measured, can be used to calculate a position line on a nautical or aeronautical chart. A common use of the sextant is to sight the…


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The name derives from the Greek word “to cheat”. The essential component of this device is a glass disk upon which are arranged figures radially, representing a moving object in successive positions. On turning the disk, and projecting a light beam…

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Analytical balances are accurate and precise instruments for weighing chemical samples. They require a dust-free and draft-free location on a solid bench that is free of vibrations. The samples must be measured at room temperature to prevent natural…


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The galvanometer is a current measuring device. Gustav H. Wiedemann's version of the galvanometer was developed in 1874. The coils on either side of the suspended needle could be moved back and forth to change the sensitivity, and a series of coils,…

Kaleidoscopes operate on the principle of multiple reflection, where several mirrors are attached together. There are three rectangular lengthwise mirrors. Setting the mirrors at a 45 degree angle creates eight duplicate images of the objects, six at…

A tachometer (revolution-counter, Tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analogue…
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