Browse Items (54 total)

This model shows a geometric surface called a hyperboloid of one sheet. It was used in mathematics and architecture classes. The wires are straight lines. For any point on the surface, there are two straight lines lying entirely on the surface which…

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…

The tangent galvanometer is a current measuring device. It was first described in an 1837 paper by Claude-Servais-Mathias Pouillet (1790-1868), who later employed this sensitive form of galvanometer to verify Ohm's law. To use the galvanometer, it is…

The telegraph was invented by the artist and scientist Samuel Finley Breese Morse (1791-1872), who conceived the idea of the printing telegraph during an ocean voyage to Europe in 1832. The actuation of an electromagnet in the receiver would cause a…

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…

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…

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…

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.

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…

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.