Accession No


Brief Description

reflecting telescope, Newtonian “Herschel Telescope”, by William Herschel, English, 1790 (c)




Herschel, William


astronomy; optical

Earliest Date


Latest Date


Inscription Date


glass; metal (brass, speculum metal, steel wire); wood (mahogany); rope (string) (replaced by flexible steel wire in 2015).


footprint of stand: 1390mm x 590mm height of stand: 1815 mm height of top of barrel from ground (at flattest inclination) : 1880mm length of barrel: 3110mm (approx) primary mirror diameter 228 mm (9ins); depth 47mm mirror cover diameter 23mm; depth 36mm secondary mirror diameter 38mm; length 44mm eyepiece length 85mm; maximum diameter 60mm long eyepiece length 326mm; maximum diameter 61mm

Special Collection

Robert Whipple collection


Made by Herschel for George III (King’s cabinet maker making stand and tube) and then presented by George III to Duke of Marlborough (after royal visit on 17/08/1786) and kept at Blenheim. Given by 7th Duke to Mr. J. A. Hardcastle. Presented to Robert Stewart Whipple by Mr. Howard Marryat.


From the Observatory,
Sept. 3, 1829,
See p. 71 of the Inventory’ (printed label with miscellaneous parts)

Description Notes

10-ft Newtonian reflecting telescope. Tube and stand in mahogany, of Herschel’s standard pattern. Fine vertical and lateral motions; course vertical and lateral motions; all standard. Brass finder. Brass eyepiece. Wooden cover. Hinged end for fitting primary mirror. Primary 9-inch speculum metal mirror in brass mount with handle and brass cover.

Two additional eyepieces (one long with five screw-fit sections); 4 brass pieces for fitting eyepieces; 2 secondary mirrors (speculum metal, one bound in brass) with brass covers. Miscellaneous screws etc (8 in total) in paper with printed label (see inscription).

Condition: telescope fair (some cracks), other parts fair (some corrosion); complete.


James Hyslop; 'Two late 18th-century telescopes'; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge; 2008:


This huge reflecting telescope was made by Sir William Herschel in around 1790. It uses a concave mirror of 9-inch diameter to gather and focus light. The mirror is made from a solid piece of metal using an especially reflective alloy called ‘speculum’. The lens’s surface was shaped and polished by hand by Herschel.

Herschel was a German emigre musician who settled in Bath, England, where he spent his spare time building telescopes and observing the night sky. He achieved public acclaim and royal favour through his discovery of the planet Uranus in 1781, the first new planet to have ever been discovered (Mercury, Venus, Mars, Jupiter and Saturn are all visible to the naked human eye). Herschel had attempted to call the new planet ‘Georgium Sidus’ (’George’s Star’), to honour King George III, but dissent from astronomers outside Britain lead to the choice of a less politically-divisive name, Uranus.

Impressed and flattered, George III made Herschel private astronomer to the King, a post that provided Herschel with enough money to take up astronomical observation full time. In return, George III requested that Herschel make a number of telescopes, and this is one of five 10-ft reflecting telescopes made for the King. Following Herschel’s standard design, the King’s cabinet maker constructed the mahogany stand and tube, whilst Herschel made the optical parts himself.

The provenance of the Herschel telescope has been well documented. George III presented it to the Duke of Marlborough and it was placed in the Observatory in Blenheim Palace. It was later given to Herschel’s great-grandson, Mr. Joseph A. Hardcastle (1816-1911), by the seventh Duke of Marlborough. The Hardcastle family then sold it to Howard Marryat in 1927, and Marryat then gave it to Robert Whipple in 1944 to mark the foundation of the Whipple Collection.
Created by: Joshua Nall on 19/12/2013


Images (Click to view full size):