Herschel's Telescope, c 1839.
© National Media Museum / Science & Society Picture Library
An experimental photograph on paper printed from a glass negative taken by Sir John Herschel (1792-1871) in about 1839. 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.