Holtz-type influence machine
date: label: date made
content: ca 1875
label: date made
content: ca 1870
name: label: associated person
content: Holtz
label: maker
content: Ruhmkorff, Heinrich Daniel
notes: label: Description (Brief)
content: 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.
label: Description (Brief)
content: 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.
label: Description (Brief)
content: This machine—with two plates, one fixed and one that rotates--was made by Heinrich Ruhmkorff (1803-1877) of Germany in his Paris workshop. He is best known for the development of an induction coil still known as a Ruhmkorff coil. Designed by Wilhelm Holtz (1836–1913) four glass rods mounted on a mahogany base support two glass discs about 22" (56 cm) in diameter. The operator cranks driving pulleys to spin one plate. An extra set of combs are set at right angles to the ones typically seen in the basic Holtz design. One plate has two holes and paper tabs.
label: Description (Brief)
content: This machine was repaired in late 1958 and the parts replaced included the stationary plate, stationary plate holding-support screw, stationary plate positioning knob and ferrule, and the drive belts for the rotating plate The original glass plates are in storage.
label: Description (Brief)
content: Wilhelm Holtz was a German physicist who described a plate electrical machine in 1865, and a slightly modified form in 1867. The "Ruhmkorff a / Paris" inscription is that of Heinrich Daniel Ruhmkorff, a German instrument maker who worked in Paris.
label: Description (Brief)
content: James Swaim, a Smithsonian agent in Paris, bought this example for the Institution in 1867, and was reimbursed $100. Another Ruhmkorff machine with four plates designed in the 1870s is catalog #328747.
label: Description (Brief)
content: References: "On Some New Forms of Electrical Apparatus," American Journal of Science 43 (March 1867): 747-248. Invoice for James Swaim in Paris, for Holtz electrical apparatus, dated March 26, 1867. SI Fiscal Records, SI Archives, R.G. 000093, Box 115.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
label: See more items in
content: Science & Mathematics
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.311761
label: catalog number
content: 311761
label: accession number
content: 152769
objectType: label: Object Name
content: Electrostatic Machine
label: Object Name
content: electrostatic generator
label: Object Name
content: influence machine
label: Other Terms
content: electrostatic generator; Electrostatic Devices
physicalDescription: label: Measurements
content: overall: 27 1/4 in x 27 1/2 in x 17 in; 69.215 cm x 69.85 cm x 43.18 cm