Rev. John Craig | William Gravatt | Thomas Slater | George Rennie

Society for the History of Astronomy Channel 4's Time Team Programme Webmaster Concept Design 01732 300155 Grateful thanks to all those that have provided many of the articles, references and details in these pages This is a non-profit site               Largest refracting telescopes in the world Refractors are limited by the laws of physics. Gravity bends the lens’ perfect shape, deforming it as the telescope is pointed to different parts of the night sky. The insurmountable problem of providing support to the lens at its centre meant that a limit of around half a metre would put paid to larger lenses being constructed. The largest refractor in existence today is the mighty Yerkes near Chicago in the United States. Its 40-inch lens was lovingly figured by the Clark brothers in 1897.     For several years the Craig Telescope was to be the largest in the world. Despite this limitation, refractors have the advantage over reflectors in that there is no central obstruction which lowers the contrast of planetary detail and spreads starlight, preventing astronomers examining close binary stars. Refracting telescopes were not completely abandoned when huge leaps in aperture were accomplished by the reflector in the first part of the 1900s. Indeed several “large” refractors were constructed as late as 1942! What follows is a list of the largest refractors ever built. Some have been dismantled, some destroyed and some relocated. However, many are still in operation today. Diam(ins) Diam(m) Year Description Country 49.0ins 1.25m 1900 Mounted horizontally with a sidereostat mirror 2 meters in diameter placed in front. Disassembled after the Paris exhibition in November 1900. More>> France 40.0ins 1.02m 1897 The world’s largest refractor, Yerkes Observatory, Williams Bay, Wisconsin. More>> USA 36.0ins 0.91m 1888 James Lick Telescope, Lick Observatory, Mt Hamilton. More>> USA 32.0ins 0.81m 1889 Observatory of Paris, Meudon France 31.5ins 0.80m 1899 The Great Refractor, Astrophysical Observatory, Potsdam. More>> Germany 30.0ins 0.76m 1914 Thaw Refractor, Allegheny Observatory, Pittsburgh. More>> USA 30.0ins 0.76m 1886 Bischoffsheim Observatory, Nice. More>> France 30.0ins 0.76m 1885 Central Astronomical Observatory, Poulkova. More>> Russia 28.0ins 0.71m 1893 Royal Observatory, Greenwich, London. More>> England 27.6ins 0.70m 1896 Treptow Observatory, Berlin. Germany 27.0ins 0.68m 1927 Lamont-Hussey Observatory, Bloemfontein. South Africa 26.8ins 0.68m 1880 University Observatory, Vienna. Austria 26.5ins 0.67m 1925 University Observatory, Johannesburg. South Africa 26.0ins 0.66m 1873 United States Navel Observatory, Washington. USA 26.0ins 0.66m 1883 Leander McCormick Observatory, Charlottesville, Virginia. USA 26.0ins 0.66m 1897 Thompson Refractor, Royal Observatory, Greenwich, London England 26.0ins 0.66m 1889 Yale Observatory, Johannesburg. South Africa 25.6ins 0.65m   Berlin-Badelsberg University Observatory, Neubabelsberg. Germany 25.6ins 0.65m   Imperial University Observatory Mitika. Japan 25.6ins 0.65m   Astronomical Observatory of the University of Belgrade Serbia (former Yugoslavia) 25.6ins 0.65m 1942 Schauinsland Observatory, Breisgau. Germany 25.0ins 0.63m 1869 Solar Physocs Observatory, Cambridge. England 24.1ins 0.61m 1896 Lowell Observatory, Flagstaff, Arizona. USA 24.0ins 0.61m 1852 Craig Observatory, Wandsworth Common, London England 24.0ins 0.61m   Observatory of Paris, Meudon. France 24.0ins 0.61m   Radcliffe Observatory, Oxford. England 24.0ins 0.61m   National Astronomical Obserevatory, Santiago. Chile 32.0ins 0.61m 1901 Royal Observatory, Cape of Good Hope. South Africa 24.0ins 0.61m 1931 Stockholm Observatory, Saltsjöbaden. Sweden 24.0ins 0.61m 1911 Sproul Observatory, Swarthmore, Pennsylvania USA 24.0ins 0.61m 1893 Harvard College Observatory, Bloemfontein. South Africa 23.6ins 0.60m 1924 Einstein Turm Observatory, Pottsdam. Germany 23.6ins 0.60m 1914 Hamburg Observatory, Bergedorf. Germany 23.6ins 0.60m 1890 National Observatory, Paris. France 23.6ins 0.60m 1928 Bosscha Observatory, Lembang. Java 23.0ins 0.58m 1882 Princeton University Observatory, Princeton, New Jersey. USA 21.0ins 0.53m 1889 Grande Lunette, Meudon. France 20.5ins 0.52m 1913 Observatoire, Jarry-Desloges, Setif. Algeria 20.0ins 0.51m   Van Vleck Observatory, Wesleyan University, Middletown, Connecticut. USA     Idea for the telescope The 24-inch lens   The Great Telescope at the Paris Exhibition of 1900. This huge horizontal telescope had an aperture of 49-inches! courtesy Wikipedia