Thomson-Houston Single Arc Lamp
date: label: date made
content: ca 1880
name: label: maker
content: Thomson-Houston Electric Company
notes: label: Description
content: Thomson-Houston single arc lamp (carbons and globe missing), circa 1880. Arc lamps like this provided illumination for large indoor spaces in the late nineteenth century. A carbon rod about 1 cm in diameter mounts on the bottom plate, while another attaches to the end of the central brass rod. That brass rod slides up through the box and out a hole in the wooden upper plate. The box protects an electro-mechanical regulator that maintains a set distance between the ends of the two carbon rods. To start, the carbon rods (electrodes) touch, allowing electricity to pass through both. As they are separated, an electrical arc is established between the two that provides light and consumes the rods. As the rods are consumed, the electrical resistance in the lamp changes. The electro-mechanical regulator senses the changing resistance and slowly lowers the brass rod to maintain the proper operating distance between the rods. A milk-glass globe attached to the lamp using the three set screws on the bottom plate, and acted as a diffuser for the intense arc light.
setName: label: See more items in
content: Work and Industry: Electricity
label: Exhibition
content: Lighting a Revolution
label: Exhibition Location
content: National Museum of American History
creditLine: label: Credit Line
content: from the Museum of Science and Industry (Chicago)
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.327945
label: catalog number
content: 327945
label: accession number
content: 271855
objectType: label: Object Name
content: Arc Lamp
label: Other Terms
content: Arc Lamp; Lighting Devices
physicalDescription: label: Measurements
content: overall: 34 in x 18 in x 9 1/4 in; 86.36 cm x 45.72 cm x 23.495 cm