List of largest optical telescopes in the 19th century

This list of largest optical telescopes in the 19th century includes what were large optical telescopes for their time. See List of largest optical telescopes in the 20th century for later telescopes. The list includes various refractors and reflectors that were active at some time between about 1799 to 1901.
The main material used early on for reflecting telescope mirrors was speculum metal, which reflected only about two-thirds of the incident light, and which tarnished, requiring maintenance. Two-element refracting telescopes were extensively used in 19th century observatories despite their smaller apertures than metal, and later glass, mirror telescopes.
The technology for silver-coating glass mirrors, more reflective than speculum metal and not subject to tarnishing, was developed in the mid-19th century but was slow to be adopted. A major technology advance of this time was the development of photography, permitting astrophotography, and some telescopes were tailored to this application. A wide variety of scientific instruments were developed for use with telescopes, such as for spectroscopy and various astronomical measurements.

Reflectors and refractors

Early reflectors using speculum metal had some of the record-breaking apertures of the day, but not necessarily high performance. Starting in the 1860s metal coated glass reflector telescopes proved more durable, for example the Crossley Reflector, which continued to be used and upgraded even into the 21st century. Refracting telescopes, with lenses, especially achromatic doublets, rather than mirrors were popular in the 19th century.

Name/Observatory	Aperture cm	Type	Location then	Extant*
Leviathan of Parsonstown		[Speculum metal\|reflector Speculum metal\|– metal]	Birr Castle; Ireland	1845–1908?
A.A. Common 60-inch		reflector – glass	England, UK	1891–1904
Herschel 40-foot		reflector – metal	Observatory House; England, UK	1789–1815
Great Paris Exhibition Telescope of 1900		achromat – siderostat	Paris 1900 Exposition, France	1900–1901
Great Melbourne Telescope		reflector – metal	Melbourne Observatory, Australia	1869
William Lassell 48-inch		reflector – metal	Malta	1861–1865
National Observatory, Paris		reflector-glass	Paris, France	1875–1943
Yerkes Observatory		achromat	Williams Bay, Wisconsin, USA	1897
Meudon Observatory 100 cm		reflector-glass	Meudon Observatory, France	1891
James Lick telescope, Lick Observatory		achromat	Mount Hamilton, California, USA	1888
Crossley Reflector		reflector – glass	Lick Observatory, USA	1896
A. A. Common Reflector		reflector – glass	Great Britain	1880–1896
Rosse 36-inch Telescope		reflector – metal	Birr Castle; Ireland	1826
Grande Lunette, Paris Observatory	83 cm + 62 cm	achromat x2	Meudon, France	1891
83-cm Reflector, Toulouse Observatory		reflector-glass	Toulouse, France	1875
Potsdam Großer Refraktor Astrophysical Observatory Potsdam	80 cm + 50 cm	achromat x2	Potsdam, Deutsches Kaiserreich	1899
Foucault 80 cm, Marseille Observatory		reflector-glass	Marseille, France	1862–1965
Grand Lunette Bischoffsheim, Nice Observatory		achromat	Nice, France	1886
Pulkovo observatory		achromat	Saint Petersburg, Russian Empire	1885–1941/44
Royal Observatory, Greenwich		reflector	Greenwich, England, UK	1897
28-inch Grubb Refractor – Royal Greenwich Observatory		achromat	Greenwich, London, Great Britain	1894
Henry Draper 28-inch		reflector-glass	United States	1871
Großer Refraktor, Vienna Observatory		achromat	Vienna, Austrian Empire	1880
Great Treptow Refractor, Treptow Observatory		achromat	Berlin, Germany	1896
McCormick Observatory		achromat	Charlottesville, Virginia, USA	1883
U.S. Naval Observatory		achromat	Washington, DC, USA	1873
Royal Greenwich Observatory		achromat	Herstmonceux, Great Britain	1896
Newall Telescope		refractor	Gateshead, England, UK	1869
Lowell Observatory		achromat	Arizona, USA	1896
Craig telescope		achromat	Wandsworth Common, London, UK	1852–1857
William Lassell 24-inch		reflector – metal	Liverpool, England, UK	1845
Royal Observatory, Edinburgh		reflector	Edinburgh, Scotland, UK	1872
Daramona 24-inch reflector		reflector – glass	Streete, Ireland	1881–1971
Radcliffe Double Refractor, Radcliffe Observatory	60/45 cm		reflector – metal	Observatory House; England, UK	1782–?
Schröter 27-foot Newtonian		reflector – metal	Lilienthal, Lower Saxony	1793–1813?
18½-inch Dearborn Observatory Refractor		achromat	Chicago, Evanston, Illinois, USA	1862
Flower Observatory		achromat	Philadelphia, USA	1896
Royal Observatory		achromat	Cape Colony, South Africa, British Empire	1897
Merz & Mahler Refractor, Pulkovo observatory		achromat	Saint Petersburg, Russian Empire	1839
Harvard Great Refractor, Harvard College Observatory		achromat	Cambridge, Massachusetts, USA	1847
Armagh 15-inch Grubb Reflector		reflector – metal	Armagh Observatory, Northern Ireland	1835
Paris Observatory 38 cm Brunner		achromat	Paris, France	1857
Lunette coudée, Lyon Observatory	36.6 cm	achromat	Saint-Genis-Laval, France	1887
Markree Observatory 13.3-inch Grubb/Cauchoix		refractor	County Sligo, United Kingdom of Great Britain and Ireland	1834
The 12.8 Inch Merz refractor at Royal Greenwich Observatory		refractor	Greenwich, England	1850s
McMillin Observatory 12½-inch		refractor	Ohio, USA	1895; 1896–1968
Bamberg Refractor, Wilhelm Foerster Observatory in Berlin		achromat	Urania Observatory, Berlin-Moabit, Prussia / Berlin, Germany	1889–1945
Grubb refractor,		achromat	Oxford, England, UK	1874
University of Illinois Observatory		achromat	Urbana, Illinois, USA	1896
Great refractor of Amici, Florence Observatory La Specola		achromat	Florence, Italy	1841
Merz und Mahler, Cincinnati Observatory		achromat	Cincinnati, Ohio, USA	1843
Repsold Refractor, Leiden Observatory		achromat	Leiden, The Netherlands	1885
Mills Observatory		achromat	United Kingdom	1871
Fraunhofer Refractor, United States Naval Observatory		achromat	Foggy Bottom, D.C., USA	1844
Quito Astronomical Observatory		Great refractor	Quito, Ecuador	1875
Fraunhofer-Refraktor, Berlin Observatory		achromat	Berlin-Kreuzberg, Deutsches Kaiserreich	1835
Great Dorpat Refractor Dorpat/Tartu Observatory		achromat	Dorpat, Governorate of Livonia, Russian Empire / now Tartu, Estonia	1824
Van Monckhoven Telescope	23 cm	refractor	Ghent, Belgium, UGENT Observatory Armand Pien	1880
Sheepshanks Equatorial of Royal Greenwich Observatory		achromat	Greenwich, England, UK	1838
Merz Refractor, Leiden Observatory		achromat	Leiden, The Netherlands	1838
Wesleyan University 6-inch Lerebours refractor		achromat	Connecticut, USA	1836
Shuckburgh telescope		achromat	Warwickshire, England, UK	1791–1923
Utzschneider & Fraunhofer Comet Seeker		acrhomat	Foggy Bottom, D.C., USA	1843
Ertel Comet Seeker Markree Observatory	7.62	achromat	Markree, Ireland	1842–1873