List of largest optical telescopes in the 18th century

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A James Short's reflecting telescope;this English telescope maker produced almost 1400 Gregorian reflectors in the mid-1700s. Mobile versions were used to observe the Transit of Venus.

List of largest optical telescopes in the 18th century, are listings of what were, for the time period of the 18th century, large optical telescopes. The list includes various refractor and reflector that were active some time between about 1699 to 1801. It is oriented towards astronomy, not terrestrial telescopes (e.g. spyglass).

Many of the largest were metal mirror reflectors, some of which had substational apertures even for the 20th century. One problems was that many instrument makers including Herschel did not pass on their mirror making craft, and by the next century reflectors had largely been passed over in favour of small achromats (2 lens refractors). It was not until the 20th century that really large reflectors would predominate once again. Some of the achievements in astronomy of the 19th century telescopes include the discovery of the planet Uranus, the Messier catalog, and overall increased detections of comets, stars, star catalogs, and other charting.

The major breakthrough in the 1700s, was the discovery of two and even three lens telescopes and increased spread of reflecting telescopes and their designs. In this period reflectors used metal mirrors not metal coated glass, which was not pioneered until the next century.

Selected Reflectors & Refractors[edit]

The main telescope technologies during this period were refractors with non-achromatic objectives (single lens), speculum metal reflectors, refractors with achromatic doublets objective (doublet lens), and apochromatic triplets (after 1760s) objectives. The list is inherently limited by what examples and records survived.


Name(s) Aperture
cm (in)
Type Significance Location then/Original Site Extant*
Herschel 40-foot (1.26 m diameter)[1] 126 cm(49.5″) Reflector World's largest 1789;
Mimas & Enceladus discovery telescope
Observatory House, Slough, England 1789–1815
Rev John Michell's Gregorian reflector[2] 75 cm (29.5″) Reflector - Gregorian World's largest 1780 Yorkshire, Great Britain 1780–1789
Herschel "X Feet"[3] or "Large 10 Feet"[4] 61 cm (24″) Reflector England 1800
Father Noel's Gregorian reflector[2] 60 cm (23.5″) Reflector - Gregorian World's largest 1761; 1796 Newtonian conversion Paris, France 1761-1841[5]
James Short Gregorian reflector 50 cm (19.5") Reflector - Gregorian World's largest 1750 Scotland 1750
Schröter 27 foot Newtonian[3] 47 cm (18.5") Reflector Lilienthal, Lower Saxony (Germany) 1793-1813
Herschel 20-foot[6][7] 47 cm (18.5″) Reflector Observatory House; England 1782
James Short Reflector for King of Spain[3] 46 cm (18.1″) Reflector - Gregorian Spain 1752
James Short's Gregorian reflector 38 cm (14″) Reflector - Gregorian World's largest 1734 Scotland 1734
Huygens aerial for Royal Society of London[8] 19 cm (7.5″) aerial London, England 1691-1786[9]
William Herschel 7-foot[8] 16 cm (6.3″) Reflector Used to discover Georgium Sidus (Uranus) England 1776–1783
Hadley's Reflector[10] 15 cm (6″) Reflector First parabolic newtonian England 1721
Van Deyl of Amsterdam telescope[11] 11.4 cm (4.5″) achromat England 1781
James Short 4.5 inch reflector 11.4 cm (4.5″) reflector England 1737[12]
Shuckburgh telescope 10 cm (4.1″) achromat First large equatorial[13] Warwickshire, England 1791–1923
Dollond Apochromatic Triplet[14] 9.53 cm (3.75″) apochromat First apochromatic triplet England 1763[14]
Dollond Triplet for Wollaston[15] 9.02 cm triple lens RAS No. 16 England 1771[16]
Francesco Bianchini's aerial telescope[17] 6.6 cm (2.6") aerial Rome, Italy 1726
Chester Moore Hall's Doublet[8] 6.4 cm (2.5") achromat First achromatic doublet England 1733
Troughton Equatorial Telescope[18] 5.08 cm (2") achromat Equatorial mount Armagh Observatory, Ireland 1795
Newton's reflector[19] (1st) 3.3 cm (1.3") Reflector First reflecting telescope England 1668-1704[19]

* (First light or Build Completion to Inactive or Deconstruction)


The 40-foot (12 m) telescope

See also[edit]


  1. ^ "Original mirror for William Herschel's 40 foot telescope, 1785". Science & Society Picture Library. Retrieved 22 November 2008.
  2. ^ a b Henry C. King (2003). The History of the Telescope. Courier Corporation. p. 91. ISBN 978-0-486-43265-6.
  3. ^ a b c Henry C. King (2003). The History of the Telescope. Courier Corporation. p. 135. ISBN 978-0-486-43265-6.
  4. ^ Constance Ann Lubbock; lady Constance Ann Herschel Lubbock (1933). The Herschel Chronicle: The Life-story of William Herschel and His Sister, Caroline Herschel. CUP Archive. p. 92.
  5. ^ King, Henry C. (2003-01-01). The History of the Telescope. Courier Corporation. ISBN 9780486432656.
  6. ^ "William Herschel (1738-1822)".
  7. ^ "Exhibitions". National Air and Space Museum. 27 April 2016.
  8. ^ a b c Paul Schlyter, Largest optical telescopes of the world
  9. ^ Christa Jungnickel; Russell K. McCormmach (1996). Cavendish. American Philosophical Society. pp. 306–308. ISBN 978-0-87169-220-7.
  10. ^ "Telescope: Hadley's Reflector".
  11. ^ The Horological Journal. October 1876. p. 20.
  12. ^ "James Short's Reflecting Telescopes".
  13. ^ "Refracting telescope on equatorial mounting, 1791;". Archived from the original on 2012-03-08.
  14. ^ a b "1948PA.....56...75K Page 83".
  15. ^ "1980JBAA...90..422D Page 425".
  16. ^ Dall, H. E.; Hysom, E. J.; Ronan, C. A. (1980). "1980JBAA...90..422D Page 422". Journal of the British Astronomical Association. 90: 422. Bibcode:1980JBAA...90..422D. Retrieved 2019-10-16.
  17. ^ Moore, P. (1985). "1985JBAA...95...50M Page 50". Journal of the British Astronomical Association. 95: 50. Bibcode:1985JBAA...95...50M.
  18. ^ "Armagh Observatory". Archived from the original on 2010-02-11. Retrieved 2010-09-17.
  19. ^ a b Henry C. King (2003). The History of the Telescope. Courier Corporation. p. 74. ISBN 978-0-486-43265-6.

Further reading[edit]

External links[edit]