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157:. The objectives for aerial telescopes sometimes had very long focal lengths. Christiaan Huygens states that in 1686 he and his brother made objectives of 8 inch (200 mm) and 8.5 inch (220 mm) diameter and 170 and 210 ft (52 and 64 m) focal length, respectively. Constantijn Huygens, Jr. presented a 7.5 inch (190 mm) diameter 123 ft (37.5 m) focal length objective to the
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105:) introduced by the non-uniform refractive properties of single glass lenses. This degraded the quality of the images they produced. Telescope makers from that era found that very long focal length objectives had no appreciable chromatic aberration (the uncorrected chromatic aberration fell within the large
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in Leiden. It was commissioned by Hans de Rijk, a Dutch science promoter. It was unveiled during the first annual 'Kaiser Lente
Lezingen' (Kaiser Spring Lectures), which is a local astronomy lecture event. Unlike the original telescopes this one only has a 4-meter focal length, making it much easier
254:
who compared its performance to the 7.5 inch (190 mm) diameter aerial telescope built by
Constantijn Huygens, Jr. that the Society had in their collection. In the comparison they noted that the Hadley reflector "will bear such a charge as to make it magnify the object as many times as the
123:
they began to have focal lengths as long as 150 feet. Besides having very long tubes, these telescopes needed scaffolding or long masts and cranes to hold them up. Their value as research tools was minimal since the telescope's support frame and tube flexed and vibrated in the slightest breeze and
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Around 1675 the brothers
Christiaan and Constantijn Huygens decided to accommodate the very long focal length objectives they were creating by eliminating the tube altogether. In the Huygens' "aerial" telescope the objective was mounted inside a short iron tube mounted on a swiveling ball-joint on
148:
The
Huygenses contrived some ingenious arrangements for aiming these "aerial telescopes" at an object visible in the night sky. The telescope could be aimed at bright objects such as planets by looking for their image cast on a white pasteboard ring or oiled translucent paper screen and then
46:, which was connected to the objective by a string or connecting rod. By holding the string tight and maneuvering the eyepiece, the observer could aim the telescope at objects in the sky. The idea for this type of telescope may have originated in the late 17th century with the
149:
centering them in the eyepiece. Fainter objects could be found by looking for the reflection of a lamp held in the observer's hand being bounced back by the objective and then centering that reflection on the object. Other contrivances for the same purpose are described by
133:
top of an adjustable mast. The eyepiece was mounted in another short tube (sometimes on a stand), and the two tubes were kept aligned by a taut connecting string. Christiaan
Huygens published designs for these tubeless "aerial telescopes" in his 1684 book
161:
in 1690. Adrien Auzout and others made telescopes of from 300 to 600 ft (90 to 180 m) focal length, and Auzout proposed a huge aerial telescope 1,000 ft in length that he would use "to observe animals on the Moon".
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to operate as compared to the original. The telescope is so far the only known fully working replica in the world. It can be seen on open days at the Old
Observatory and on special request during tours.
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After about 1675, therefore, astronomers did away with the telescope tube. The objective was mounted on a building or pole by means of a ball-joint and aimed by means of a string...
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pattern at focus). They also realized that when they doubled the diameter of their objectives they had to make the objective's focal length 4 times as long (focal length had to be
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tried to map the surface of that same planet and deduce its rotational period in Rome in 1726 using a 2.6" (66 mm) 100 foot focal length aerial telescope.
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latter with its due charge", and that it represented objects as distinct, though not altogether so clear and bright as the
Huygens aerial telescope.
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115:) to achieve the same amount of minimal chromatic aberration. As the objective diameter of these refracting telescopes was increased to
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was mounted on a pole, tree, tower, building or other structure on a swivel ball-joint. The observer stood on the ground and held the
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The extreme difficulty of using these very long focal length telescopes led astronomers to develop alternative designs. One was the
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194:. On this tower he mounted long tubed telescopes and the objectives of aerial telescopes made for him by the Italian optician
84:'s 8 inch telescope with an open work wood and wire "tube" that had a focal length of 150 feet to limit chromatic aberration.
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137:, and their invention has been attributed to him and his brother Constantijn, although similar designs were also used by
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174:
An engraving of The Paris
Observatory in the beginning of the 18th century with the wooden "Marly Tower" on the right.
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The need for very long focal length refracting telescope objectives was finally eliminated with the invention of the
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An engraving of
Huygens's 210-foot aerial telescope showing the eyepiece and objective mounts and connecting string.
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425:, Center for History of Physics, a Division of the American Institute of Physics, archived from
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Animation explaining the need for very long focal length lenses due to
Chromatic aberration.
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Institute and Museum of the History of Science - Galileo's telescope - Chromatic aberration
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with an aerial telescope whose objective had a focal length of 212 ft (65 m).
38:, built in the second half of the 17th century, that did not use a tube. Instead, the
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In May 2014 a working replica of an aerial Huygens telescope was unveiled at the Old
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Francesco Bianchini holding another style eyepiece mount for an aerial telescope.
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with a 6-inch diameter mirror. The instrument was examined by Society members
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451:"Christian Huygens and the Development of Science in the Seventeenth Century"
768:
58:
668:
43:
785:. Extensive detail on Cassini, Huygens and Optics, and Campani's lenses.
694:"Leidse replica van Huygens' buisloze kijker zaterdag onthuld in Hortus"
93:
Telescopes built in the 17th and early 18th century used single element
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Mirror, Mirror: A History of the Human Love Affair with Reflection
215:
169:
75:
18:
648:, BRITISH ASTRON. ASSOC. JOURNAL V. 95, NO.2/FEB, P. 50, 1985
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had the wooden Marly Tower, originally built as part of the
490:. Museo Galileo - Istituto e Museo di Storia della Scienza
301:
Huygens' telescope set up at the Old Observatory in Leiden
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The complete Amateur Astronomer - John Hadley's Reflector
743:
The Planet Mars: A History of Observation and Discovery
629:
This paragraph is adapted from the 1888 edition of the
198:. In 1684 he used one of his aerial telescopes to find
68:, though it is not clear if they actually invented it.
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List of largest optical telescopes of the 18th century
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to lift water for the reservoirs and fountains at the
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444:
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780:ESA - Proceedings of the International Conference
556:
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423:Cosmic Journey: A History of Scientific Cosmology
214:, on December 27, 1722, measured the diameter of
97:lenses that suffered from interfering rainbow
8:
658:amazing-space.stsci.edu - Hadley’s Reflector
579:The 600-foot telescope and monstrous insects
488:"Galileo's telescope - Chromatic aberration"
382:
380:
141:; the idea is even sometimes attributed to
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505:
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723:"Huygenskijker Oude Sterrewacht Leiden"
563:Largest optical telescopes of the world
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291:
264:
413:
411:
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262:in the middle of the 18th century.
783:Titan, from discovery to Encounter
604:Price, Fred William (2000-12-11),
14:
16:Tubeless telescope (17th century)
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822:
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124:sometimes collapsed altogether.
769:Huygens and His Great Refractor
607:The planet observer's handbook
240:Newtonian reflecting telescope
190:, moved to the grounds of the
80:1673 engraved illustration of
1:
390:The history of the telescope
128:Tubeless "aerial" telescopes
89:Very long "tubed" telescopes
885:
679:Pound reported upon it in
313:Huygens' Telescope closeup
519:, Cartage, archived from
513:"How Telescopes Improved"
180:Giovanni Domenico Cassini
72:Invention and application
683:, 1723, No. 378, p. 382.
325:History of the telescope
135:Astroscopia Compendiaria
95:non-achromatic objective
66:Constantijn Huygens, Jr.
631:Encyclopædia Britannica
387:King, Henry C. (2003),
335:List of telescope types
330:Infinite-axis telescope
159:Royal Society of London
31:is a type of very long
548:, 1710, vol. i. p. 261
419:"The First Telescopes"
175:
85:
24:
517:History of Telescopes
362:. The Galileo Project
188:Gardens of Versailles
173:
79:
22:
645:The Mapping of Venus
449:Bell, A. E. (1948),
232:reflecting telescope
206:, two satellites of
121:resolve finer detail
103:chromatic aberration
36:refracting telescope
467:1948Natur.162..472A
220:Francesco Bianchini
155:Nicolaas Hartsoeker
151:Philippe de la Hire
740:Sheehan, William.
286:Leiden Observatory
176:
86:
62:Christiaan Huygens
25:
617:978-0-521-78981-3
461:(4117): 472–473,
400:978-0-486-43265-6
192:Paris Observatory
117:gather more light
82:Johannes Hevelius
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700:. Archived from
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196:Giuseppe Campani
184:Machine de Marly
143:Christopher Wren
64:and his brother
29:aerial telescope
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869:Telescope types
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360:"The Telescope"
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260:achromatic lens
242:to the British
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763:External links
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51:mathematician
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853:Solar System
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752:. Retrieved
748:the original
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702:the original
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681:Phil. Trans.
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431:, retrieved
427:the original
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364:. Retrieved
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283:
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229:
226:Obsolescence
177:
166:Applications
147:
134:
131:
110:
92:
33:focal length
28:
26:
841:Outer space
829:Spaceflight
587:, page 97.
248:James Pound
236:John Hadley
178:Astronomer
107:diffraction
754:2012-03-05
734:References
708:2016-10-28
643:Moore, P,
433:2009-05-06
234:. In 1721
55:astronomer
805:Astronomy
238:showed a
59:physicist
40:objective
863:Category
319:See also
280:Replicas
44:eyepiece
791:Portals
494:5 March
463:Bibcode
366:5 March
153:and by
112:squared
614:
591:
536:, 1715
455:Nature
397:
208:Saturn
204:Tethys
817:Stars
346:Notes
216:Venus
200:Dione
99:halos
48:Dutch
612:ISBN
589:ISBN
496:2012
395:ISBN
368:2012
250:and
202:and
119:and
57:and
581:in
471:doi
459:162
27:An
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696:.
577:,
553:^
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457:,
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393:,
379:^
370:.
210:.
145:.
53:,
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757:.
725:.
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101:(
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