Cylinder-type Electrostatic 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.
For many years electrostatic machines like this one from Wesleyan University were considered essential tools for teaching the basic concepts of electrical science and saw significant use. Though in poor condition, this machine shows the basic components of a typical 19th century cylinder generator. The cylinder is set in brass hubs and was turned by a direct-drive crank. The leather rubbing pad with silk cloth provided the friction that generated the static charge. A collector set opposite the rubbing pad gathered the charge for experimental use. 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 are no extant maker’s marks so the exact age or origin of this machine is unknown at this time.
Location
Currently not on view
Physical Description
wood (overall material)
glass (overall material)
brass (overall material)
steel (overall material)
cloth (overall material)
Measurements
overall: 27 in x 28 in x 20 1/2 in; 68.58 cm x 71.12 cm x 52.07 cm
ID Number
1989.0029.11
accession number
1989.0029
catalog number
1989.0029.11
Credit Line
from Wesleyan University, Department of Physics
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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