Heliostat

A clockwork mirror followed the sun and bounced its light in one fixed direction for photography or experiments.

Date: around 1900
Maker: John A. Brashear
Place: United States: Pennsylvania, Pittsburgh
Dimensions: overall: 20 in; 50.8 cm; overall: 18 1/2 in x 12 3/8 in x 12 1/2 in; 46.99 cm x 31.4325 cm x 31.75 cm
Museum: National Museum of American History
Credit line: U.S. Military Academy

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.” inscription refers to John A. Brashear who began making telescopes in 1880, in a shop behind his house in Pittsburgh, and who established a new shop in Allegheny, then a suburb of Pittsburgh, in the fall of 1886.

Ref: John A. Brashear, Catalogue (Allegheny, 1906), p. 35.

The museum's own record (Smithsonian, National Museum of American History)