This microscope has 3 objectives. It belonged to Dr. O.F. Parish.

Made in Berlin. 3694 Int Ohm richtig bei 20 degrees C Manganin. Side plate says U of W 47 A1062.

Transcontinental telephone cable containing 560 copper wires.This aerial cable required an attached steel cable for support.

The rolling double cone serves as a demonstration of how gravity acts on an object’s center of mass. When released, the edges of the rolling double cone appear to move up its triangular support, but in reality the cone’s center of mass is still rolling downwards. The concept of the center of mass is older than the rolling double cone, which seems to have become a popular instrument in the 1700s. Some early versions of the cone were less elegantly constructed from rulers and screws, and could produce results that were unreliable. Nevertheless, its simplicity made it a useful and easy-to-understand demonstration when well carried out, and it was well-known in England by the eighteenth century. Several textbooks and course outlines from that time period cite it as one of the more important phenomena to be understood when it came to understanding laws of gravity and motion. The rolling double cone experiment was used in classrooms and illustrated and explained in textbooks to help explain to students how gravity worked. It is still being used in introductory physics classes at Grinnell today, as a way of demonstrating the importance of the concept of center of mass, and to show how counterintuitive it can be. -Lilly Haight 2018 References Clarke, Henry. The rationale of circulating numbers, with the investigations of all the rules and peculiar processes used in that part of decimal arithmetic. To which are added, several curious mathematical questions; With Some Useful Remarks on Adfected Equations, and the Doctrine of Fluxions. Adapted to the Use of Schools. London, 1777, pp. 89. Desaguliers, John T. A course of mechanical and experimental philosophy. Whereby any one, although unskill'd in mathematical sciences, may be able to understand all those phænomena of nature, which have been discovered by geometrical principles. London, 1725, pp. 3. Desaguliers, John T. A course of experimental philosophy. London, 1763. Worster, Benjamin. A Course of Experimental Philosophy. London, 1730.

The Leyden Jar was a sensational advancement for studies of electricity in the 18th century. A high voltage device made from simple materials, it was the first condenser, a precursor to the capacitor, storing electric energy until discharged. Such a device enabled a number of medical, engineering, and experimental applications. The Leyden Jar is a wide mouthed glass with metal wrapped around the outside and on the inside. The jar is filled with water or another liquid such as alcohol. A metal rod passes through the nonconductive top, reaching down to the liquid. When an electric charge is created (in this period, by an electrostatic friction machine) and somebody or a conductive object touches both the metal top of the rod and the outside metal, an electric shock jumps springs between the rod and the conductive agent, discharging the electricity stored in the jar's glass. Two parties are credited with its invention, independently but around the same time: Ewald Georg von Kleist and Pieter van Musschenbroek, in 1745-1746. Musschenbroek and his assistant, Andreas Cunaeus, are given the namesake as they published their findings. It is named for the town and the University of Leiden, where they worked. Beyond its scientific merit, it was promoted commercially as a 'flask' for wealthy people with scientific wonder. The Leyden jars at Grinnell College are arranged in a box configuration, an advancement made by Benjamin Franklin in 1747-1748. This setup creates the "Leyden Battery," allowing a stronger charge to be collectively built and stored. Such a design enabled the invention of the wireless telegraph at the beginning of the 20th century. -Felipe Gentle 2017 References Katz, Eugenii. "Pieter (Petrus) Van Musschenbroek." Musschenbroek. Institute of Chemistry, Hebrew University of Jerusalem, 2004. Web. 12 Apr. 2017. Terra Incognita Interactive Productions. "'Electrical Battery' of Leyden Jars, 1760-1769." The Benjamin Franklin Tercentenary. Franklin and Marshall College, n.d. Web. 12 Apr. 2017. Wikisource contributors. "1911 Encyclopædia Britannica/Leyden Jar." Wikisource . Wikisource , 8 Sep. 2016. Web. 13 Apr. 2017. _________________________________________ A Leyden jar is a device made from a glass jar coated inside and out with metal sheets and a conducting rod inserted vertically through the jar to make contact with both the inner and outer sheets. The Leyden jar was the first form of a capacitor or condenser—a circuit device which stores electrical charge. It was independently designed by both the German deacon Ewald Georg von Kleist in 1744 and the Dutch scientists Pieter van Musschenbroek and Andreas Cunaeus in 1746 at the University of Leyden—hence its name. The development of the Leyden jar derives from an early conception of electricity as a fluid, wherein electricity was thought to be storable in containers using water or alcohol. Early attempts at storing electricity featured the conduction of electricity into a water-filled jar and discharging this electricity to the ground through a human interface. Successfully development allowed charging of the jar through the connection of one terminal of an electrostatic generator to the conducting rod and one to the outer foil. After charging, Leyden jars proved to be useful as portable sources of current through which experiments and demonstrations could be carried out, possibly in contexts where the use of an electrostatic generator is inconvenient and/or impossible. These particular Leyden jars are connected in parallel which allows for the storage of greater charge than an individual jar. This parallel connection was pioneered by Benjamin Franklin, who’s study of Leyden jars—and electricity in general—helped contribute the “drastic revision of the [electricity] fluid theory. . . and the first full paradigm for electricity” (Kuhn, The Structure of Scientific Revolutions, p. 62). -Ben Hoekstra 2019

Gift from Robert Noyce at Intel to Grinnell College Physics Department. Paper-tape reader for Intellec 8 8080-development system.

Gift from Robert Noyce at Intel to Grinnell College Physics Department

1979 Gift from Steve Jobs to Grinnell College

First single-board computer used in electronics course

Origin: Roy, NM Catalog Number: 234.40 Sample Weight: 678 g Acquired from H. H. Nininger

Origin: Lincoln Co., CO Catalog Number: 328.9 Sample Weight: 127.5 g Total Weight: 33.6 kg Type: Stone Acquired from H.H. Nininger

Origin: Sonora, Mexico Catalog Number: 9.1 Sample Weight: 324.5 g Type: Siderite Acquired from H. H. Nininger