Sheepshanks equatorial

Lore & Background

The Sheepshanks Equatorial Telescope was installed in 1838 at the Royal Observatory in Greenwich, donated by the astronomer Richard Sheepshanks. It featured a doublet objective lens made by Cauchoix of Paris and was originally mounted on a clockwork driven equatorial mounting by the Grubb Telescope Company on a stone pillar. The telescope tube was made of wood. Its focal length is uncertain, quoted as either 6 feet 2+1⁄2 inches (1.892 meters) or 8 feet 2 inches (2.49 meters) in different sources.

From 1835 to 1963 it was housed in the Sheepshanks Dome at Greenwich Observatory, located between the later Great Equatorial Building and the Prime Meridian. It was then moved to the Altazimuth Pavilion from 1963 to 1982, after which it was placed in storage in the early 1980s. An 1840 report praised the telescope, noting 'The power and general goodness of this telescope make it a most welcome addition to the instruments of the observatory.' By 1896, W. H. M. Christie reported that its definition was good, with minor defects including a small quantity of colour from the secondary spectrum and diffusion of light from brilliant objects.

The telescope was used for various observations, including Comet Encke, the Moon occulting stars in 1905 (such as Bradley 687, 130 Tauri, and 26 Geminorum), and the moons of Jupiter. It was equipped with a wire micrometer. At one time it was the largest aperture telescope at Greenwich.

Reader's Guide

The Sheepshanks Equatorial Telescope holds significance as a long-serving instrument at the Royal Observatory, Greenwich, from its installation in 1838 until being placed in storage in the early 1980s. It was the largest aperture telescope at Greenwich at one time, reflecting the observatory's investment in improved observational capabilities. Its donation by Richard Sheepshanks and its construction by notable makers—Cauchoix for the lens and Grubb for the mounting—underscore the collaborative nature of 19th-century astronomical instrument making. The telescope's longevity is evidenced by its use for observations spanning over six decades, including Comet Encke, lunar occultations of stars in 1905, and the moons of Jupiter. The conflicting reports on its focal length highlight the challenges in historical documentation. Its legacy is also tied to the Sheepshanks Dome, a dedicated structure that housed it for over a century, and to the broader Sheepshanks name, which appears on other telescopes, such as a 4.6-inch aperture instrument used with a spectroscope in the 1860s and a telescope at Cambridge completed in 1898.

Did You Know?

• The Sheepshanks Equatorial Telescope had a doublet objective lens made by Cauchoix of Paris.
• Its focal length is disputed: one source says 6 feet 2+1⁄2 inches, another says 8 feet 2 inches.
• The telescope was used to observe the Moon occulting stars in 1905, including Bradley 687, 130 Tauri, and 26 Geminorum.