Browse Items (54 total)

instruments 001.JPG
A current balance measures the force of repulsion between two wires, each carrying an electric current. An upper wire is fixed in place, and the wire directly below it is free to move. The currents are adjusted so that the electrical attractive force…

instruments 021.JPG
A five decade variable resistor made by Max Kohl of Chemnitz. The 0.1 and 1 ohm resistors are slide wires along the front and back of the top, and the three upper ranges use coils of low-temperature coefficient resistance wire (probably constantan).…

differential thermopile.JPG
NOT YET LOCATED. When two wires made of different metals are connected to make a loop, and the two junctions between the wires are held at different temperatures, a voltage is produced and electrical current can be detected with a sensitive current…

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instruments 005.JPG
The basic discharger is simply a conductor used to discharge a Leiden jar. The two arms are spread apart at the hinged joint, and the insulated handle prevents the operator from receiving a shock as the knobs are touched against the outer foil and…

Film Projector.JPG
This picture should be rotated 90 degrees clockwise to show how the instrument was actually used. This kinetoscope was manufactured by Edison Mfg, Co, Orange, N.J., USA. around 1902. Continuous 35mm film wrapped around the reel, and turning the crank…

instruments 027.JPG
The label of this electric motor notes that it is a 1/6 HP, 130 Volt motor made by the Crocker Wheeler Motor Company of New York. The patent dates are May 5 and September 22, 1891.

instruments 006.JPG
In the nineteenth century almost all power supplies were direct current (DC). In order to step voltage up or down, the direct current had to be converted to alternating current (AC), stepped using transformers, and then converted back to DC. The…

instruments 026.JPG
This is a demonstration device showing two aspects of electric charge. When the conducting sphere atop the vertical stand is charged (e.g. by using a Leyden jar) the horizontal pinwheel device at the top begins to spin as charge is leaked from its…

Washington and Lee Lab1.jpg
This picture shows the electrical experimentation room in Reid Hall around 1900. The tangent galvanometer visible in the picture above had been moved and can be seen at the right. Just to the left of it is the Kelvin current balance still in the…

Fountain in a Vacuum.JPG
"The “Fountain in Vacuo” is a perfectly delightful and entertaining 19th century demonstration that is never done today. Volume 1 of Pike’s Illustrated Catalogue of Optical, Mathematical and Philosophical Instruments (New York, 1856) describes…

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