# 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 ('Silver on 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 (see also great refractor).
   * Reflector (Metal mirror) or unknown
   * Glass Reflector (Silver on glass mirror)
   * Refractor (Lens)
| Name/Observatory | Aperture cm (in) | Type | Location then (Original Site) | Extant* |
| Leviathan of Parsonstown | 183 cm (72") | reflector – metal | Birr Castle; Ireland | 1845–1908? |
| A.A. Common 60-inch | 152.4 cm (60") | reflector – glass | England, UK | 1891–1904 |
| Herschel 40-foot (1.26 m diam.) | 126 cm (49½") | reflector – metal | Observatory House; England, UK | 1789–1815 |
| Great Paris Exhibition Telescope of 1900 | 125 cm (49.21") | achromat – siderostat | Paris 1900 Exposition, France | 1900–1901 |
| Great Melbourne Telescope | 122 cm (48") | reflector – metal | Melbourne Observatory, Australia | 1869 |
| William Lassell 48-inch | 122 cm (48") | reflector – metal | Malta | 1861–1865 |
| National Observatory, Paris | 1.2 m (47") | reflector-glass | Paris, France | 1875–1943 |
| Yerkes Observatory | 102 cm (40") | achromat | Williams Bay, Wisconsin, USA | 1897 |
| Meudon Observatory 100 cm | 100 cm (39.4") | reflector-glass | Meudon Observatory, France | 1891 |
| James Lick telescope, Lick Observatory | 91 cm (36") | achromat | Mount Hamilton, California, USA | 1888 |
| Crossley Reflector | 91.4 cm (36") | reflector – glass | Lick Observatory, USA | 1896 |
| A. A. Common Reflector | 91.4 cm (36") | reflector – glass | Great Britain | 1880–1896 |
| Rosse 36-inch Telescope (The 3-foot) | 91.4 cm (36") | reflector – metal | Birr Castle; Ireland | 1826 |
| Grande Lunette, Paris Observatory | 83 cm + 62 cm (32.67" + 24.40") | achromat x2 | Meudon, France | 1891 |
| 83-cm Reflector, Toulouse Observatory | 83 cm (32.67") | reflector-glass | Toulouse, France | 1875 |
| Potsdam Großer Refraktor Astrophysical Observatory Potsdam | 80 cm + 50 cm (31½" + 29½") | achromat x2 | Potsdam, Deutsches Kaiserreich | 1899 |
| Focault 80 cm, Marseille Observatory | 80 cm (31.5") | reflector-glass | Marseille, France | 1862–1965 |
| Grand Lunette Biscoffscheim, Nice Observatory | 77 cm (30.3") | achromat | Nice, France | 1886 |
| Pulkovo observatory | 76 cm (30") | achromat | Saint Petersburg, Russian Empire | 1885–1941/44 |
| Royal Observatory, Greenwich | 76.2 cm (30") | reflector | Greenwich, England, UK | 1897 |
| 28-inch Grubb Refractor – Royal Greenwich Observatory | 71 cm (28") | achromat | Greenwich, London, Great Britain | 1894 |
| Henry Draper 28-inch (Harvard College Observatory since 1889) | 71 cm (28") | reflector-glass | United States | 1871 |
| Großer Refraktor, Vienna Observatory | 69 cm (26") | achromat | Vienna, Austrian Empire | 1880 |
| Great Treptow Refractor, Treptow Observatory | 68 cm (26.77") | achromat | Berlin, Germany | 1896 |
| McCormick Observatory | 67 cm (26.37") | achromat | Charlottesville, Virginia, USA | 1883 |
| U.S. Naval Observatory | 66 cm (26") | achromat | Washington, DC, USA | 1873 |
| Royal Greenwich Observatory | 66 cm (26") | achromat | Herstmonceux, Great Britain | 1896 |
| Newall Telescope | 62.5 cm (24.6") | refractor | Gateshead, England, UK | 1869 |
| Lowell Observatory | 61 cm (24") | achromat | Arizona, USA | 1896 |
| Craig telescope | 61 cm (24") | achromat | Wandsworth Common, London, UK | 1852–1857 |
| William Lassell 24-inch | 61 cm (24") | reflector – metal | Liverpool, England, UK | 1845 |
| Royal Observatory, Edinburgh | 61 cm (24") | reflector | Edinburgh, Scotland, UK | 1872 |
| Daramona 24-inch reflector | 61 cm (24") | reflector – glass | Streete, Ireland | 1881–1971 |
| Radcliffe Double Refractor, Radcliffe Observatory | 60/45 cm (23.6″/18") | achromat x2 | Oxford, UK | 1901 |
| Halstead Observatory | 58.4 cm (23") | achromat | Princeton, New Jersey, USA | 1881 |
| Institut technomatique | 52 cm (20½") | refractor | Paris, France | 1857 |
| Chamberlin Observatory | 50 cm (20") | achromat | Colorado, USA | 1891 |
| Nasymth 20-inch | 50 cm (20") | reflector – metal | United Kingdom | 1842 |
| Imperial Observatory (Straßburg) | 48.5 cm (19.1") | achromat | Straßburg/Strasbourg, German Empire/France | 1880 |
| Herschel 20-foot (0.475 m diam.) | 47.5 cm (18½") | reflector – metal | Observatory House; England, UK | 1782–? |
| Schröter 27 foot Newtonian | 47 cm (18½") | reflector – metal | Lilienthal, Lower Saxony (Germany) | 1793–1813? |
| 18½-inch Dearborn Observatory Refractor | 47 cm (18½") | achromat | Chicago (1862–1893), Evanston, Illinois (1893), USA | 1862 |
| Flower Observatory | 46 cm (18") | achromat | Philadelphia, USA | 1896 |
| Royal Observatory | 46 cm (18") | achromat | Cape Colony, South Africa, British Empire | 1897 |
| Merz & Mahler Refractor, Pulkovo observatory | 38 cm (15") | achromat | Saint Petersburg, Russian Empire | 1839 |
| Harvard Great Refractor, Harvard College Observatory | 38 cm (15") | achromat | Cambridge, Massachusetts, USA | 1847 |
| Armagh 15-inch Grubb Reflector | 38 cm (15") | reflector – metal | Armagh Observatory, Northern Ireland | 1835 |
| Paris Observatory (Arago Telescope) 38 cm Brunner | 38 cm (15") | achromat | Paris, France | 1857 |
| Lunette coudée, Lyon Observatory | 36.6 cm | achromat | Saint-Genis-Laval, France | 1887 |
| Markree Observatory 13.3-inch Grubb/Cauchoix | 34 cm (13.3") | refractor | County Sligo, United Kingdom of Great Britain and Ireland | 1834 |
| The 12.8 Inch Merz refractor at Royal Greenwich Observatory | 32.5 cm (12.8") | refractor | Greenwich, England | 1850s |
| McMillin Observatory 12½-inch | 31.75 cm (12½") | refractor | Ohio, USA | 1895; 1896–1968 |
| Bamberg Refractor, Wilhelm Foerster Observatory (since 1963) in Berlin | 31.4 cm (12.36") | achromat | Urania Observatory, Berlin-Moabit, Prussia / Berlin, Germany | 1889–1945 |
| Grubb refractor, Keele Observatory | 31 cm (12.25") | achromat | Oxford, England, UK | 1874 |
| University of Illinois Observatory | 30 cm (12") | achromat | Urbana, Illinois, USA | 1896 |
| Great refractor of Amici (Amici I), Florence Observatory La Specola | 28.4 cm (11.2") | achromat | Florence, Italy | 1841 |
| Merz und Mahler (Mitchell cupola), Cincinnati Observatory | 28 cm (11") | achromat | Cincinnati, Ohio, USA | 1843 |
| Repsold Refractor (10-duims), Leiden Observatory | 26.6 cm (10½") | achromat | Leiden, The Netherlands | 1885 |
| Mills Observatory | 25 cm (10") | achromat | United Kingdom | 1871 |
| Fraunhofer Refractor, United States Naval Observatory (Foggy Bottom) | 24.4 cm (9.6") | achromat | Foggy Bottom, D.C., USA | 1844 |
| Quito Astronomical Observatory | 24 cm (9½") | Great refractor | Quito, Ecuador | 1875 |
| Fraunhofer-Refraktor, Berlin Observatory | 24 cm (9.6") | achromat | Berlin-Kreuzberg, Deutsches Kaiserreich (1835–1913) | 1835 |
| Great Dorpat Refractor (Fraunhofer) Dorpat/Tartu Observatory | 24 cm (9.6") | 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 | 17 cm (6.7") | achromat | Greenwich, England, UK | 1838 |
| Merz Refractor (6-duims), Leiden Observatory | 16.6 cm (6½") | achromat | Leiden, The Netherlands | 1838 |
| Wesleyan University 6-inch Lerebours refractor | 15.24 cm (6") | achromat | Connecticut, USA | 1836 |
| Shuckburgh telescope | 10 cm (4.1") | achromat | Warwickshire, England, UK | 1791–1923 |
| Utzschneider & Fraunhofer Comet Seeker | 10.2 cm (4") | acrhomat | Foggy Bottom, D.C., USA | 1843 |
| Ertel Comet Seeker Markree Observatory | 7.62 (3") | achromat | Markree, Ireland | 1842–1873 |
* (First light or Build Completion to Inactive (Retired) or Deconstruction)