Cylinder-type Electrostatic Machine

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.
This machine, made around 1785, has a hand-cranked cylinder and a leather pad with silk cloth to mounted on one side. The mount is adjustable by means of the wooden screw set in the base. A prime conductor would be mounted opposite the rubbing pad but is missing from this unit. During the 1750s electrical researchers refined the design of electrostatic machines by replacing earlier spherical globes with a glass cylinder, a design used for many years. This change increased the surface area of the glass in contact with the rubbing pad and improved the efficiency of the generator. There is no extant maker's mark on the machine although it is of the type designed by Edward Nairne in the 1780s. Nairne (1726-1806) of England made electrical and other scientific devices.
Location
Currently not on view
Object Name
galvanometer
electrostatic generator
electrostatic machine
date made
ca 1785
Physical Description
wood (overall material)
glass (overall material)
brass (overall material)
leather (overall material)
cloth (overall material)
Measurements
overall: 25 1/2 in x 25 3/4 in x 16 1/4 in; 64.77 cm x 65.405 cm x 41.275 cm
ID Number
EM*322996
catalog number
322996
accession number
249201
See more items in
Work and Industry: Electricity
Science & Mathematics
Electrostatic Machines
Data Source
National Museum of American History, Kenneth E. Behring Center

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