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…
Reichsschatzmeister Schwarz spricht in Gegenwart des Führers und Reichskanzlers vom Balkon des neuen Führerhauses zu den Teilnehmern. Im Hintergrund sind die beiden neu errichteten Ehrentempel und das Verwaltungsgebäude der NSDAP, am Koenigsplatz zu…
Many pieces of demonstration equipment must be rotated to show a desired effect. A Rotator is a device with a crank that can rapidly rotate a small horizontal platform about an axis. Other pieces of equipment, like Newton’s Color Wheel, attached to…
Selected pages from the copybook/math journal of the Nelson family. Exhibits the type of elements contained in the journal - math proofs, personal notes, history records, a type of index, geneological records, etc.
A sextant is used in nautical navigation measure the angle between two visible objects. The angle, and the time it was measured, can be used to calculate a position line on a nautical or aeronautical chart. A common use of the sextant is to sight the…
This model shows a geometric surface called a hyperboloid of one sheet. It was used in mathematics and architecture classes. The wires are straight lines. For any point on the surface, there are two straight lines lying entirely on the surface which…
A tachometer (revolution-counter, Tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute (RPM) on a calibrated analogue…
The tangent galvanometer is a current measuring device. It was first described in an 1837 paper by Claude-Servais-Mathias Pouillet (1790-1868), who later employed this sensitive form of galvanometer to verify Ohm's law. To use the galvanometer, it is…
The telegraph was invented by the artist and scientist Samuel Finley Breese Morse (1791-1872), who conceived the idea of the printing telegraph during an ocean voyage to Europe in 1832. The actuation of an electromagnet in the receiver would cause a…
This early relative of the slide rule has a cylinder 4 in. in diameter and 18 in. long that rotates and slides in and out between the array of twenty equally-spaced parallel bars. The bars have a scale with numbers spaced logarithmically, as on a…