Telescopium Herschelii, or Herschel's Telescope, is an obsolete constellation created by Maximilian Hell in 1789 to honor Herschel's discovery of Uranus by carving out an inconspicuous region on the east side of Auriga, next to Lynx. It originally consisted of two constellations that lay on either side of the region where Herschel observed Uranus: Tubus Hershelii Major and Tubus Hershelii Minor, the former representing (although inaccurately) Herschel's 20-foot telescope, and the latter (also inaccurately) the 7-foot telescope used by Herschel to discover Uranus. In his 1801 atlas Bode replaced Tubus Hershelii Major with Telescopium Herschelii (and an accurate sketch of the 7-foot telescope, based on instruments he had purchased from Herschel), but discarded Tubus Hershelii Minor. The constellation appeared in some later atlases but was never in great use, and was formally discarded when the IAU codified the present list of 88 constellations in 1922.
Historical Map of Telescopium Herschelii
From Bode's 1801 Uranographia (Image Credit and © Tartu Observatory Virtual Museum; used by permission)