Slough, Berkshire

William Herschel (1738-1822) and Caroline Herschel (1750-1848) moved to Observatory House, Slough, from Datchet in April 1786 and remained until his death here. Arago [p.262] says the house was provided by the King. In 1788, William married Mrs Pitt, a widow in nearby Upton. In 1787, he announced two moons of Uranus and in 1798, he announced four more. In 1787-1789, he built, with the King's financial assistance, a 49 inch reflecting telescope with a 39 ft 4 in (usually referred to as 40 ft) iron tube of diameter 58 in. It cost at least £4800. Another source says George III contributed the estimated £1395 cost, and when the cost reached £2947, he immediately paid the difference - despite his legendary stinginess, the king was generous in his support of science. With this telescope, he discovered the sixth and seventh moons of Saturn, Mimas and Enceladus, on 28 Aug 1789 and 17 Sep 1789 [Arago, p.295]. This telescope remained the largest ever made until Lord Rosse's at Birr, Ireland, in 1845. However, Herschel had used his own optical system where the image is formed directly at the top edge of the tube - though this does away with the secondary mirror, it introduces distortions and is difficult to adjust. The telescope was awkward to use, requiring two men to move, and the mirror tended to tarnish. It was last used in Aug 1815 and was dismantled in 1822. Herschel's main work here was with his 'large 20 foot', now at Greenwich, and he determined the shape of our galaxy as a disc, explaining the Milky Way. At some point he discovered binary stars. Around 1800, he discovered infra-red radiation and studied its properties for several years. Caroline acted as assistant and amanuensis to William and has been recognised as a major contributor to their work. She had her own telescope, she discovered 8 comets, including the 1795 comet later recognised as periodic with period 3.3 years and now named Encke's Comet in honour of Encke's 1818 determination of its orbit; and she catalogued 2500 nebulae. After William's marriage, she eventually moved out and lodged at various places in the neighbourhood. After her brother's death, she returned to Hanover in October 1823. In 1838, the 40 ft telescope mounting was found to be unsafe and it was taken down in 1839. John Herschel made some of the earliest photographs in Autumn 1839, of the mounting before the demolition - one of these photos is dated 30 November. Arago [p.265] says the mirror was 58 inches and the family sealed up the tube on 1 January 1840. The tube remained on the site, though damaged by a falling tree, until the house was demolished in 1961 - it is now [1988] Rank Xerox offices. The mirror and the remains of the tube are in the Old Royal Observatory, Greenwich. (See London other institutions.) [Thoday, item 9; P. Moore, pp.9-11; Arago; P. Moore (2); P. Moore (4), pp.30-33 with photos]


John Frederick William Herschel (1792-1871) was born here [Ball (5), p.126]. He was appointed Assistant to his father in 1816.

William is buried in St. Laurence's Church, Upton, with a wall tablet [Greenwood (2), pp.177-178]. In the late 1990s a bequest of £10,000 from Miss Nora Cruikshank led to the commissioning of the Herschel Window. Designed by Andrew Taylor, the beautiful stained glass window depicts the sun, moon and the planets that were known in his lifetime and in the order in which they were discovered. Herschel is also shown using his telescope.


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