Voss double-acting influence machine
date: label: date made
content: ca 1910
notes: label: Description (Brief)
content: People from ancient times knew that rubbing certain materials and then touching something caused a spark. Studying what is called electrostatics laid the groundwork for understanding electricity and magnetism. Natural philosophers, scientists, and instrument makers created many ingenious devices to generate electrostatic charges starting in the 1600s. These machines varied in size and technique but all involved rotary motion to generate a charge, and a means of transferring the charge to a storage device for use.
label: Description (Brief)
content: Many early electrostatic machines generated a charge by friction. In the later 19th century several designs were introduced based on induction. Electrostatic induction occurs when one charged body (such as a glass disc) causes another body (another disc) that is close but not touching to become charged. The first glass disc is said to influence the second disc so these generators came to be called influence machines.
label: Description (Brief)
content: This influence machine appears to be a duplex design from Robert Voss of Germany. In 1880 Voss combined the ideas of August Toepler and Wilhelm Holtz and produced an influence machine with two plates (see catalog #315900). A few years later he revised his design and added a third plate as seen in this object. Two plates rotate on either side of a fixed plate. The fixed plate has two paper sectors covering tin foil conductors and two brushes are mounted on the edge (one is missing from this unit). The front rotating plate has six brass contacts (one is missing) but there are no windows as would be seen on a Holtz machine. The second rotating plate has no contacts or windows and is simply a blank plate to prevent the charge from dissipating from that side of the fixed plate. There is a switch on the bottom to connect the two Leyden jars. The neutralizer arm attached to the center of the axle has brass brushes set amid the brass combs. This unit almost matches the design seen in Voss' US patent #410053 of 27 August 1889, though one of the electrodes differs slightly from the patent design.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
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content: Science & Mathematics
creditLine: label: Credit Line
content: from Columbia University, Department of Physics, thru Alvin P. Tramm
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.322936
label: catalog number
content: 322936
label: accession number
content: 249200
objectType: label: Object Name
content: electrostatic generator
label: Object Name
content: influence machine
physicalDescription: label: Measurements
content: overall: 15 in x 21 1/2 in x 12 in; 38.1 cm x 54.61 cm x 30.48 cm