Object Details
- 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 portable generating machine from around 1760 comes with an experimental kit of accessories. Early electrostatic machines generated a charge by spinning a globe against a pad. The charge could then be used directly in experiments or transferred from the globe to a Leyden jar. The hand-cranked ball of sulfur on this machine rubbed against a leather pad. The pins on the brass rod set close to the ball transferred the charge from the ball to the rod, called a prime conductor. Suspended from a frame by insulating silk threads, the charged prime conductor allowed a researcher to show electrical properties like attraction, repulsion, and strength of charge. Accessories include pith balls, a chime of bells, a Leyden jar, and assorted plates, hooks and dischargers.
- This machine is especially interesting as we have an original design drawing in the collection showing this type of machine--catalog #1988.0621.01.
- Data Source
- National Museum of American History
- date made
- ca 1750
- Credit Line
- Acquired in part by the generosity of Edison Electric Institute
- Physical Description
- wood (overall material)
- glass (overall material)
- brass (overall material)
- silk (overall material)
- metal (overall material)
- sulfur (overall material)
- leather (overall material)
- Measurements
- overall: 57 cm x 27.5 cm x 67 cm; 22 7/16 in x 10 13/16 in x 26 3/8 in
- Object Name
- generator, electrostatic
- frictional globe machine
- electrostatic generator
- Other Terms
- frictional globe machine; Electrostatic Devices
