Browse Items (54 total)

The heliostat takes light from the sun as it tracks across the sky, and redirects it in a fixed direction. To accomplish this, the light is reflected from a mirror that reproduces the motion of the sun, except at twice the rate. Although he did not…

Glass, when stressed, shows the property of double refraction: light of differing polarization directions bends differently passing through the glass. When placed between crossed polarizers , bands of color may be seen, with the spacing of the bands…

NOT YET LOCATED. The term “galvanometer” is in current use, naming an instrument which indicates the strength of an electric current. The Galvanoscope is an earlier instrument, which shows the presence of the current but gives only a rough…

In 1844 Froment devised an electric motor that was one of the first used for industrial purposes. In his design, electromagnets are energized to attract iron bars mounted on a revolving cage. Once the iron bar is level with the electromagnet, the…

"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 it,…

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…

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…

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…

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.

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…