Ruhmkorff-type duplex influence machine
date: label: date made
content: ca 1890
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 four-plate machine follows a design by Heinrich Ruhmkorff (1803-1877) of Germany. Although unmarked, the machine is quite similar to another in the collection that has a Ruhmkorff nameplate. (Catalog #311761) Building on earlier designs by Wilhelm Holtz and Johann Poggendorff, this so-called duplex machine features two fixed plates set between two rotating plates. According to John Gray’s 1890 review of “Electrical Influence Machines,” Ruhmkorff “simplified and improved” Poggendorff’s 1870 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 Amherst College Thru: Prof. Theodore Soller, Chairman
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.328747
label: catalog number
content: 328747
label: accession number
content: 277678
objectType: label: Object Name
content: influence machine
label: Object Name
content: electrostatic generator
label: Other Terms
content: electrostatic generator; Electrostatic Devices
physicalDescription: label: Measurements
content: overall: 27 in x 29 in x 19 in; 68.58 cm x 73.66 cm x 48.26 cm