Browse Items (54 total)

When this device is connected between two points in a circuit, it measures the relative voltage between the points by passing current through a coil of many turns of fine wire which, in turn, causes the needle to deflect.  

This was the culmination of over a century of development of current-measuring instruments which relied on the interaction of currents with static magnetic fields. These instruments were mounted on a solid wall to prevent vibration, and a telescope…

When the large center disk, made of non-conducting material with metallic strips attached, was turned using a hand crank, fixed metallic brushes rubbed against the metallic strips causing them to become charged. The charge was drawn off and collected…

Prisms have been standard laboratory equipment since Isaac Newton used one in 1666 to study the nature of the spectrum. Most or all of these prisms were made by Duboscq in Paris.

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…

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…

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,…

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…

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…

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…