Parabolic Mirror
notes: label: Description
content: Speculum metal is an alloy of around two-thirds copper and one-third tin that can be polished to make a highly reflective surface. Isaac Newton used speculum for his reflecting telescope in 1668, and many others did likewise until the introduction of silvered-glass mirrors. This example, which may date from the mid-nineteenth century, is about 12 inches diameter and weighs 49 pounds.
label: Location
content: Currently not on view
setName: label: See more items in
content: Medicine and Science: Physical Sciences
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.337151
label: catalog number
content: 337151
label: accession number
content: 1979.0026
objectType: label: Object Name
content: mirror
physicalDescription: label: Measurements
content: overall: 42 mm x 31.2 cm; 1 21/32 in x 12 9/32 in
label: Measurements
content: overall: 12 1/4 in x 1 1/2 in; 31.115 cm x 3.81 cm
label: Measurements
content: overall: 13 in x 13 in x 3 in; 33.02 cm x 33.02 cm x 7.62 cm
label: Measurements
content: overall: p7147: 25 in x 72 in x 48 in; 63.5 cm x 182.88 cm x 121.92 cm