Voss influence machine

Voss influence machine

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Description (Brief)
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.
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.
In 1880 Robert Voss of Berlin combined the ideas of August Toepler and Wilhelm Holtz and produced an influence machine with two plates. Where Toepler used two fixed plates, Voss used only one. Voss’ machine used paper appliqués called sectors on the fixed plate for generating the charge, as in Holtz’s machine, but he added tin foil contacts between the paper and glass and did not use windows. Six brass knobs set on the rotating disc were contacted by two pairs of brushes. One pair is on the central brass arm called the neutralizer, and the other pair attach to arms holding them on the fixed plate. According to an 1890 account the changes made the machine “not so susceptible to damp weather as the Holtz machine.” In 1889 Voss received US Patent 410053 for a similar influence machine with two rotating plates.
This machine was repaired in late 1958 and the parts replaced included the rotating plate, stationary plate support, four brush collectors, and the drive belt for the rotating plate. One of the two Leyden jars is broken and the fixed plate is cracked.
Location
Currently not on view
Object Name
electrostatic generator
influence machine
date made
ca 1890
Measurements
overall: 17 in x 25 in x 13 in; 43.18 cm x 63.5 cm x 33.02 cm
ID Number
EM.315900
catalog number
315900
accession number
222953
See more items in
Work and Industry: Electricity
Science & Mathematics
Data Source
National Museum of American History
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