Browse Items (54 total)

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,…

This gimbaled, eight-day marine chronometer is a deck clock made by Waltham in Waltham, Massachusetts, made around 1910. The mount is to keep the clock face horizontal even if the box (and ship) roll in various ways.  A glass plate covered the…

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…

In this machine a fixed plate of glass has two metallic foil sectors glued onto it. The slightly-larger rotating plate has six foil dots with raised studs glued to it; the foil sectors are large enough so that two of the studs are opposite each…

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.  

Manufactured about 1920 by Voigtländer & Sohn AG of Braunschweig, Germany.  A folding plate camera using a 6x9cm film back. It has a Voigtländer Anastigmat Voigtar 105mm f/6.3 lens set in a IBSOR DDR shutter made by AGC and having the AGC…

A vacuum pump is a device that removes gas from a sealed volume in order to leave behind a partial vacuum. The first vacuum pump was invented in 1650 by Otto von Guericke. This 19th century pump is made of brass.

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…

This late 19th century instrument is often called a Ruhmkorff coil, after the Parisan apparatus manufacturer Heinrich Daniel Ruhmkorff (1803-1877). Although he did not invent the induction coil, his name is often associated with it (particularly in…

This early relative of the slide rule has a cylinder 4 in. in diameter and 18 in. long that rotates and slides in and out between the array of twenty equally-spaced parallel bars. The bars have a scale with numbers spaced logarithmically, as on a…