Browse Items (54 total)

This was a popular piece of demonstration apparatus, in which the operation of the motor is signaled by a ringing of the bell. The instrument is an inverted revolving electromagnet, with a gearing system added to strike the bell every hundred…

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…

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).…

The three prisms hanging from the brass stand may be folded up in pairs to demonstrate achromatism (no color separation) or constant deviation (no color dependence of the angle of minimum bending of light.) These were made by Lerebours et Secretan of…

NOT YET LOCATED. The description below is not for these exact items. It belongs to a very similar item, which might nonetheless be helpful to the viewer. This cardboard aid for astronomy students was published by Henry Whitall, 512 Arch Street,…

This device demonstrates “Newton’s Rings,” colorful interference fringes caused by a thin air layer first discussed by Isaac Newton in a communication to the Royal Society in December 1675, and presented an expanded account in his book "Optics"…

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.

NOT YET LOCATED. The effects of electricity on the body can be traced back to 1745 when Pieter van Musschenbroek, testing out the one of the first Leiden jars, stated that "I felt myself struck in my arms, shoulders, and breast. I lost my breath, and…

Friedrich Wilhelm Georg Kohlrausch (1840-1910) was a professor of physics at Göttingen, Zürich, Würtzburg, Strasbourg and Berlin during his career. He wrote a widely-used book on methods of experimental physics, and developed improved measurement…

This apparatus is listed in the 1885 catalogue of Jules Duboscq of Paris as the “Grand Circle of MM. Jamin et Sénnarmont.” It was designed for the study of the laws of polarized light reflected from crystalline substances, from liquids and from…