![William Herschel (1738-1822) German-born English astronomer investigating heating effect of infra-red (published 1800) In background is Herschel's 40ft reflecting telescop Artist's reconstruction Stock Photo - Alamy William Herschel (1738-1822) German-born English astronomer investigating heating effect of infra-red (published 1800) In background is Herschel's 40ft reflecting telescop Artist's reconstruction Stock Photo - Alamy](https://c8.alamy.com/comp/TXGXX2/william-herschel-1738-1822-german-born-english-astronomer-investigating-heating-effect-of-infra-red-published-1800-in-background-is-herschels-40ft-reflecting-telescop-artists-reconstruction-TXGXX2.jpg)
William Herschel (1738-1822) German-born English astronomer investigating heating effect of infra-red (published 1800) In background is Herschel's 40ft reflecting telescop Artist's reconstruction Stock Photo - Alamy
![Astronomy: a 40-foot telescope constructed by William Herschel, in use outdoors. Coloured etching, 18--. | Wellcome Collection Astronomy: a 40-foot telescope constructed by William Herschel, in use outdoors. Coloured etching, 18--. | Wellcome Collection](https://iiif.wellcomecollection.org/image/V0024766/full/full/0/default.jpg)
Astronomy: a 40-foot telescope constructed by William Herschel, in use outdoors. Coloured etching, 18--. | Wellcome Collection
![William Herschel's reflecting telescope of 40 ft (12 m) focal length, 1789 (1807). Artist: Unknown Stock Photo - Alamy William Herschel's reflecting telescope of 40 ft (12 m) focal length, 1789 (1807). Artist: Unknown Stock Photo - Alamy](https://c8.alamy.com/comp/AJA4RF/william-herschels-reflecting-telescope-of-40-ft-12-m-focal-length-AJA4RF.jpg)