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.
- 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.
- Heinrich Wommelsdorf (1877-1945) of Germany designed this influence machine in the early 1910s. Wommelsdorf was trying to improve the older designs of August Toepler and Wilhelm Holtz. First he used discs made of plastic rather than glass or shellac. He placed metallic inductors called sectors between the two discs making a single rotor assembly. Instead of a fixed disc, the casings that cover the corners of the rotor carry the charge to the Leyden jars. As Wommelsdorf explained in US Patent 1071196, “the charges on the carriers are conducted away from the peripheral edge of the disc...instead of from the axis or laterally..., as has hitherto been usual.” He believed that change increased the efficiency of the machine by capturing more of the charge. He established the Berliner Elektros Gesellschaft in 1913 to produce this design that he called a Kondensatormaschine (condenser machine).
- Location
- Currently not on view
- ca 1920
- ID Number
- EM.330309
- catalog number
- 330309
- accession number
- 287887
- Object Name
- electrostatic generator
- influence machine
- Measurements
- overall: 18 1/2 in x 21 1/2 in x 12 in; 46.99 cm x 54.61 cm x 30.48 cm
- See more items in
- Work and Industry: Electricity
- Science & Mathematics
- National Museum of American History
- Record ID
- nmah_1396915
- GUID (Link to Original Record)
- https://n2t.net/ark:/65665/ng49ca746ab-f025-704b-e053-15f76fa0b4fa
