List of largest optical telescopes in the 18th century

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

Astronomy

Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

, not terrestrial telescopes (e.g. spyglass).

Selected Reflectors & Refractors

The main telescope technologies during this period were refractors with non-achromatic objective

Non-achromatic objective

A non-achromatic objective is an objective lens which is not corrected for chromatic aberration. In telescopes they can a be pre-18th century simple single element objective lenses which were used before the invention of doublet achromatic lenses...

s (single lens), speculum metal

Speculum metal

Speculum metal is a mixture of around two-thirds copper and one-third tin making a white brittle alloy that can be polished to make a highly reflective surface. It is used primarily to make different kinds of mirrors including early reflecting telescope optical mirrors...

reflectors, refractors with achromatic doublets objective (doublet lens), and apochromatic triplet

Apochromat

An apochromat, or apochromatic lens , is a photographic or other lens that has better correction of chromatic and spherical aberration than the much more common achromat lenses.-Explanation:...

s (after 1760s) objectives. The list is inherently limited by what examples and records survived.

Legend

Name(s)	Aperture Aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,... cm (in)	Type Telescope A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...	Significance	Location then/Original Site	Extant*
Herschel 40-foot 40-foot telescope William Herschel's 40-foot telescope, also known as the Great Forty-Foot telescope, was a reflecting telescope constructed between 1785 and 1789 at Observatory House in Slough, England. It used a 120 cm diameter primary mirror with a 12 m long focal length . It was the largest telescope in... (1.26 m diameter)	126 cm(49.5″)	Reflector Speculum metal Speculum metal is a mixture of around two-thirds copper and one-third tin making a white brittle alloy that can be polished to make a highly reflective surface. It is used primarily to make different kinds of mirrors including early reflecting telescope optical mirrors...	Worlds largest 1789	Observatory House Observatory House Observatory House was an observatory in Slough, England. It was built, run and used by the astronomer William Herschel, and his sister Caroline. The famous '40-foot telescope' - at that time the largest in the world - was housed there in the late 18th century and early 19th century.The main house... ; England England England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...	1789–1815
Rev John Michell's Gregorian reflector	75 cm (29.5″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from... - Gregorian Gregorian telescope The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke...	Worlds largest 1780	Yorkshire Yorkshire Yorkshire is a historic county of northern England and the largest in the United Kingdom. Because of its great size in comparison to other English counties, functions have been increasingly undertaken over time by its subdivisions, which have also been subject to periodic reform... , Great Britain Great Britain Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...	1780–1789
Herschel "X Feet" or "Large 10 Feet"	61 cm (24″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from...		England	1800
Father Noel's Gregorian reflector	60 cm (23.5″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from... - Gregorian Gregorian telescope The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke...	Worlds largest 1761	Paris Paris Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region... , France France The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...	1761
James Short Gregorian reflector	50 cm (19.5")	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from... - Gregorian Gregorian telescope The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke...	Worlds largest 1750	Scotland Scotland Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...	1750
Schröter 27 foot Newtonian	47 cm (18.5")	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from...		Lilienthal, Lower Saxony Lilienthal, Lower Saxony The municipality of Lilienthal belongs to the administrative district of Osterholz, Lower Saxony and borders Bremen.-History:Lilienthal belonged to the Prince-Archbishopric of Bremen. The history of the city of Lilienthal goes back to its founding as a monastery by the prince-archbishop Gerhard II... (Germany)	1793
Herschel 20-foot	47 cm (18.5″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from...		Observatory House Observatory House Observatory House was an observatory in Slough, England. It was built, run and used by the astronomer William Herschel, and his sister Caroline. The famous '40-foot telescope' - at that time the largest in the world - was housed there in the late 18th century and early 19th century.The main house... ; England England England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...	1782
James Short Reflector for King of Spain Ferdinand VI of Spain Ferdinand VI , called the Learnt, was King of Spain from 9 July 1746 until his death. He was the fourth son of the previous monarch Philip V and his first wife Maria Luisa of Savoy...	46 cm (18.1″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from... - Gregorian Gregorian telescope The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke...		Spain	1752
James Short's Gregorian reflector	38 cm (14″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from... - Gregorian Gregorian telescope The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke...	Worlds largest 1734	Scotland Scotland Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...	1734
Huygens Constantijn Huygens, Jr. Constantijn Huygens Jr. was a Dutch statesman also known for his work on scientific instruments and as a chronicler of his times... aerial for Royal Society of London	19 cm (7.5″)	aerial Aerial telescope An aerial telescope is a type of very-long-focal-length refracting telescope built in the second half of the 17th century that did not use a tube. Instead, the objective was mounted on a pole, tree, tower, building or other structure on a swivel ball-joint. The observer stood on the ground and held...		London, England	1691-1786
William Herschel 7-foot	16 cm (6.3″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from...	Discovered Georgium Sidus Uranus Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...	England	1776–1783
Hadley's Reflector	15 cm (6″)	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from...	First parabolic newtonian	England	1721
Van Deyl of Amsterdam telescope	11.4 cm (4.5″)	achromat		England	1781
Shuckburgh telescope Shuckburgh telescope The Shuckburgh telescope or Shuckburgh equatorial refracting telescope was a 4.1 inch diameter aperture telescope on a equatorial mount completed in 1791 for Sir George Shuckburgh in Warwickshire, England, and built by British instrument maker Jesse Ramsden . It was transferred to Royal...	10 cm (4.1″)	achromat	First large equatorial	Warwickshire, England	1791–1923
Dollond Peter Dollond Peter Dollond was an English maker of optical instruments, the son of John Dollond. He is known for his successful optics business, and for the invention of the apochromat.-Biography:... Apochromatic Triplet	9.53 cm (3.75″)	apochromat	First apochromatic triplet	England	1763
Francesco Bianchini Francesco Bianchini Francesco Bianchini was an Italian philosopher and scientist. He worked for the curia of three popes, including being camiere d`honore of Clement XI, and secretary of the commission for the reform of the calendar, working on the method to calculate the astronomically correct date for Easter in a... 's aerial telescope	6.6 cm (2.6")	aerial Aerial telescope An aerial telescope is a type of very-long-focal-length refracting telescope built in the second half of the 17th century that did not use a tube. Instead, the objective was mounted on a pole, tree, tower, building or other structure on a swivel ball-joint. The observer stood on the ground and held...		Rome, Italy	1726
Chester Moore Hall Chester Moore Hall Chester Moore Hall was a British lawyer and inventor who produced the first achromatic lenses in 1729 or 1733 .... 's Doublet	6.4 cm (2.5")	achromat	First achromatic doublet	England	1733
Troughton Equatorial Telescope	5.08 cm (2")	achromat	Equatorial mount	Armagh Observatory Armagh Observatory Armagh Observatory is a modern astronomical research institute with a rich heritage, based in Armagh, Northern Ireland. Around 25 astronomers are actively studying stellar astrophysics, the Sun, Solar System astronomy, and the Earth's climate.... , Ireland	1795
Newton's reflector Newton's Reflector The first reflecting telescope built by Sir Isaac Newton in 1668 is a landmark in the history of telescopes, being the first known successful reflecting telescope. It was the prototype for a design that later came to be called a newtonian telescope.... (1st)	3.3 cm (1.3")	Reflector Reflecting telescope A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from...	First reflecting telescope	England	1668-1704

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

External links

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Selected Reflectors & Refractors

Further reading

See also

External links