Early photograph of William Herschel's telescope at Slough, 1839

Early photograph of William Herschel's telescope at Slough, 1839. Entitled 'The Forty-Foot Telescope at Slough', this is one of only 25 prints made in 1890 from the original negative. This was the only image recorded of the 40 foot telescope in Slough, Berkshire assembled in 1787 by William Herschel (1738-1822), prior to its dismantling in 1839. The massive reflecting telescope used a metal mirror four feet in diameter and weighed over a ton. A wonder of the age, it quickly became a landmark visited by the rich and famous. By the time his son, Sir John Herschel (1792-1871) took this photograph, the telescope structure had become unsafe through neglect. The photograph is mounted in a frame using the rungs from John Herschel's telescope used at Slough and Cape Town, South Africa. Dimensions (overall): 390mm x 490mm. ©SSPL/Science Museum