This machine may also be refered to as a Toepler-Holtz machine.
In this machine a fixed plate of glass has two metallic foil sectors glued onto it. The slightly-larger rotating plate has six foil dots with raised studs glued to it; the foil sectors are large enough so that two of the studs are opposite each sector. In the middle is a horizontal ebonite rod, with collecting combs on the ends that are connected to Leiden jars. The vertical brass rod has metallic combs attached to its ends. The crank sets the machine in motion. At the northeast and southwest corners there are fixed metallic brushes that are in electrical contact with the foil sectors of the fixed disk. This item is an excellent match for a machine in the ca. 1900 Max Kohl catalogue.Its cost was about 70 Marks, depending on the diameter of the disk.
This machine may also be refered to as a Toepler-Holtz machine.
When two wires made of different metals are connected to make a loop, and the two junctions between the wires are held at different temperatures, a voltage is produced and electrical current can be detected with a sensitive current meter. This is the Seebeck Effect, discovered by Thomas Seebeck in 1821. The effect is multiplied when there are more than two junctions in series in the circuit, with alternate junctions in close thermal contact with each other. By measuring the current, one can measure the temperature difference of the junctions. The Differential Thermopile was invented by Macedonio Melloni (1798-1854), an Italian physicist who worked in France and Italy. Melloni's research dealt with thermal radiation, and he developed the thermopile to make quantitative measurements of the intensity of the radiation. Washington and Lee’s differential thermopile was made by E.S. Ritchie. The model with 20 pairs of junctions sold for $25.00 in the 1881 catalogue; for $40.00 you could get the 49 pair model.
]]>NOT YET LOCATED.
When two wires made of different metals are connected to make a loop, and the two junctions between the wires are held at different temperatures, a voltage is produced and electrical current can be detected with a sensitive current meter. This is the Seebeck Effect, discovered by Thomas Seebeck in 1821. The effect is multiplied when there are more than two junctions in series in the circuit, with alternate junctions in close thermal contact with each other. By measuring the current, one can measure the temperature difference of the junctions. The Differential Thermopile was invented by Macedonio Melloni (1798-1854), an Italian physicist who worked in France and Italy. Melloni's research dealt with thermal radiation, and he developed the thermopile to make quantitative measurements of the intensity of the radiation. Washington and Lee’s differential thermopile was made by E.S. Ritchie. The model with 20 pairs of junctions sold for $25.00 in the 1881 catalogue; for $40.00 you could get the 49 pair model.