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…

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…

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…

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 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…

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…

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…

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 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"…

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,…