Heliostat
date: label: date made
content: around 1900
name: label: maker
content: Brashear, John A.
notes: label: Description
content: A heliostat throws sunlight where it might be used for photography or scientific observations. This example (half of a two-mirror instrument) has a silvered-glass octagonal mirror, clockwork mechanism, and tripod base with leveling screws. The “J. A. Brashear, Allegheny, Pa. 10” inscription refers to John A. Brashear, a sell-taught optician who, with financial backing from William Thaw, a local philanthropist, could quit his job in a steel mill and devote his energies to making telescopes and related scientific apparatus. In 1886, again with help from Thaw, Brashear established an instrument shop in Allegheny, then a suburb of Pittsburgh.
label: Description
content: Brashear’s involvement with heliostats began in the summer of 1881 when Samuel Pierpont Langley, the director of the Allegheny Observatory, asked him to re-silver the surfaces of three heliostat mirrors that he would take to Mount Whitney for his pioneering researches on the solar heat. One was for a one-mirror heliostat that Alvan Clark & Sons had made for the recent transit of Venus. The other two were for a two-mirror heliostat made by William Grunow, the German immigrant who also made Langley’s early bolometers.
label: Description
content: Ref: John A. Brashear, <i>Catalogue</i> (Allegheny, 1906), p. 35.
label: Description
content: John A. Brashear, Letter to the Editor, <i>Scientific American</i> 45 (1881): 113.
label: Description
content: Samuel P. Langley, <i>Researches on Solar Heat and Its Absorption by the Earth’s Atmosphere</i> (Washington, D.C., 1884), p. 132.
label: Location
content: Currently not on view
place: label: place made
content: United States: Pennsylvania, Pittsburgh, Allegheny City
topic: label: Subject
content: Science & Scientific Instruments
setName: label: See more items in
content: Medicine and Science: Physical Sciences
creditLine: label: Credit Line
content: United States Military Academy
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.315644
label: catalog number
content: 315644
label: accession number
content: 217544
objectType: label: Object Name
content: heliostat
physicalDescription: label: Measurements
content: overall: 15 in; 38.1 cm
label: Measurements
content: overall: 15 in x 12 1/2 in x 17 3/4 in; 38.1 cm x 31.75 cm x 45.085 cm