Draft:Early telescopes

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The eyes of the princess have irises of rock-crystal enclosing a pupil. Credit: William Vaughn Tupper (1835 — 1898).

The early telescopes as manufactured in the Netherlands are refracting. The first known practical telescopes were invented in the Netherlands at the beginning of the 17th century, using glass lenses.

The earliest recorded working telescopes were the refracting telescopes that appeared in the Netherlands in 1608. Their development is credited to three individuals: Hans Lippershey and Zacharias Janssen, who were spectacle makers in Middelburg, and Jacob Metius of Alkmaar.[1] "The Hague discussed the patent applications first of Hans Lipperhey of Middelburg, and then of Jacob Metius of Alkmaar... another citizen of Middelburg, Sacharias Janssen had a telescope at about the same time but was at the Frankfurt Fair where he tried to sell it".

"Galileo always insisted that the ancients had telescopes."[2]

"The Russians have found crystal lenses, perfectly spherical and of great precision, in ancient Egypt, during the African-dominated period."[2]

"It is also only within recent years that the discovery of a seminal black kingdom in the Nile Valley, predating the Egyptian dynasties, has settled the question, once and for all, of the roots of classical Egyptian culture and technology (see Journal of African Civilizations, vol. 4, no. 2, November 1982)."[2]

Telescopes and lenses[edit]

“For we can so shape transparent bodies, and arrange them in such a way with respect to our sight and objects of vision, that the rays will be reflected and bent in any direction we desire, and under any angle we wish, we may see the object near or at a distance … So we might also cause the sun, moon and stars in appearance to descend here below.”[3]


This shows a colorless and very clean quartz that is transparent. Credit: Zimbres.

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. Pure quartz, traditionally called rock crystal (sometimes called clear quartz), is colorless and transparent or translucent.

Iceland spar, formerly known as Iceland crystal, is a transparent variety of calcite, or crystallized calcium carbonate. "It has been speculated that the sunstone (a different mineral than the gem-quality sunstone) mentioned in medieval Icelandic texts was Iceland spar and that Vikings used its light-polarizing property to tell the direction of the sun on cloudy days, for navigational purposes.[4][5]

A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect.

"c. 3500 B.C. Phoenicians cooking on sand discover glass."[6]

"Natural glass has existed since the beginnings of time, formed when certain types of rocks melt as a result of high-temperature phenomena such as volcanic eruptions, lightning strikes or the impact of meteorites, and then cool and solidify rapidly. Stone-age man is believed to have used cutting tools made of obsidian (a natural glass of volcanic origin also known as hyalopsite, Iceland agate, or mountain mahogany) and tektites (naturally-formed glasses of extraterrestrial or other origin, also referred to as obsidianites)."[7]

"According to the ancient-Roman historian Pliny (AD 23-79), Phoenician merchants transporting stone actually discovered glass (or rather became aware of its existence accidentally) in the region of Syria around 5000 BC [7,000 b2k]. Pliny tells how the merchants, after landing, rested cooking pots on blocks of nitrate placed by their fire. With the intense heat of the fire, the blocks eventually melted and mixed with the sand of the beach to form an opaque liquid."[7]

"The earliest man-made glass objects, mainly non-transparent glass beads, are thought to date back to around 3500 BC, with finds in Egypt and Eastern Mesopotamia. In the third millennium, in central Mesopotamia, the basic raw materials of glass were being used principally to produce glazes on pots and vases. The discovery may have been coincidental, with calciferous sand finding its way into an overheated kiln and combining with soda to form a coloured glaze on the ceramics. It was then, above all, Phoenician merchants and sailors who spread this new art along the coasts of the Mediterranean."[7]

Theoretical telescopes[edit]

Def. "[a] monocular optical instrument possessing magnification for observing distant objects"[8] is called a telescope.

Def. "any instrument ... for observing distant objects"[8] is called a telescope.

"From Latin telescopium, from Greek τηλεσκόπος (tēleskopos), far-seeing, from τῆλε (tēle, "afar") + σκοπέω (skopeō, "I look at)."[8]

Keplerian telescopes[edit]

This is a schematic of a Keplerian refracting telescope which uses two different sizes of planoconvex lenses. Credit: Szőcs Tamás.

The Keplerian Telescope, invented by Johannes Kepler in 1611, is an improvement on Galileo's design.[9] It uses a [plano]convex lens as the eyepiece instead of Galileo's [double] concave one. The advantage of this arrangement is [that] the rays of light emerging from the eyepiece are converging. This allows for a much wider field of view and greater eye relief but the image for the viewer is inverted. Considerably higher magnifications can be reached with this design but to overcome aberrations the simple objective lens needs to have a very high [focal ratio] f-ratio.

All refracting telescopes use the same principles. The combination of an objective lens 1 and some type of eyepiece 2 is used to gather more light than the human eye could collect on its own, focus it 5, and present the viewer with a brighter, clearer, and magnified virtual image 6.

Air telescopes[edit]

This woodcut illustration is of a 45 m focal length Keplerian air telescope built by Johannes Hevelius. Credit: Johannes Hevelius, from his book Machina coelestis (first part), published in 1673.
This is an engraving of Christiaan Huygens's 210-foot aerial telescope showing the eyepiece and objective mounts and connecting string from 1684. Credit:Christiaan Huygens.
An engraving of The Paris Observatory at the beginning of the 18th century with the wooden "Marly Tower" on the right is shown. Credit: not specified, probably C. Wolf.
Francesco Bianchini is illustrated holding another style eyepiece mount for an aerial telescope. Credit: Pier Leone Ghezzi.

At right is a woodcut illustration of a 45 m focal length Keplerian air, or aerial telescope built by Johannes Hevelius, and even longer tubeless "aerial telescopes" were constructed.

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.[10] "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..."[10] 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 the eyepiece, 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 Dutch mathematician, astronomer and physicist Christiaan Huygens and his brother Constantijn Huygens, Jr.,[11][12] though it is not clear that they invented it.[13]

An even simpler air telescope is shown in the second image at left. To have only an air telescope, an ancient needs lenses. The ones in the schematic are called planoconvex. Convex on one side towards the target and planar on the viewing side.

Possible telescopes[edit]

This is an image of a painting by artist Giorgio Vasari (1511–1574). Credit: Dodo Vasari.
The image is a crop from a painting by artist Giorgio Vasari (1511–1574) on the right. Credit: B. Precourt.
This frontispiece from the Rudolphine Tables appears to have a horizontal telescope on the upper left. Credit: Archival Photograph by Mr. Steve Nicklas, NOS, NGS.

The image at right is a painting by artist Giorgio Vasari (1511–1574). Behind and above the main focus on Cronus (Saturn) castrating Uranus (the Greek sky god before Zeus) is what appears to be "some kind of Armillary sphere"[14]. Specifically, the "[w]hole thing is some kind of Armillary sphere"[14].

Even more than that is an object angled slightly upward (right to left) that appears to be pointed at or above the large metallic ring. This object seems to be painted as if it extends through the top hole of the armillary sphere. At the upper left end of the object is an embellished end piece that may have a lens (objective lens) or piece of material the diameter of which matches that of the tube behind the embellishment. The midsection appears to taper to a smaller diameter near the right end. The right end has an even smaller piece attached or inserted that looks like an eyepiece lens holder. This tubular object seems to be receiving hands in the air praise from two people to its left. The armillary sphere may be tilted ~23 1/2°.

The tubular object bares a striking resemblance to a telescope. The image taken as a whole suggests an interaction between Cronus and Uranus as observed near the plane of the ecliptic by someone through a telescope.

Another suggestion: "It would be the sceptre, the symbolic attribute of the ruler of the deities and of the universe. It was an attribute of Uranus and is about to pass to Cronus. The nature of a sceptre as a phallic symbol seems especially obvious in the context of this painting. The ruling god and owner of the sceptre during a given mythical era is also the main progenitor of that era. (Thus mirroring an alpha male in primate and some other animal societies.)".[15] Bold added.

The Castration of Uranus is apparently a fresco by Vasari & Cristofano Gherardi (c. 1560, Sala di Cosimo I, Palazzo Vecchio, Florence).

"This painting is new to me, I must admit, and I have no idea what the object is that you refer to. It looks as though it might be [a] spindle of some kind."[16]

"I don't think it really looks like a telescope, apart from anything else it would hardly fit into the iconography of the mutilation of Uranus by Saturn. Having looked at other paintings relating to this myth, I think your so-called spindle is more likely a torch that has gone out in the chaos of the scene depicted - Maybe a metaphor for upsetting the light of the Sun or similar, who knows."[17]

The frontispiece from Johannes Kepler's Rudolphine Tables appears to have a telescope drawn in on the upper roof extension on the left side. While this would be no surprise if the drawing dates from after 1609, as suspected, it would be a surprise if this drawing dates from the 1500's.

"The central piece of information uncovered by de Waard was an entry in the unpublished journal of Isaac Beeckman, the rector of the Latin school in Dordrecht, and a friend of Descartes.37 Beeckman learned how to grind lenses for telescopes in an effort to obtain better instruments. In the early 1630's he took lessons from a spectacle-maker in Middelburg named Johannes Sachariassen, the son of Sacharias Janssen. Beeckman recorded in his journal that during one of these lessons Johannes Sachariassen told him that the first telescope in the Netherlands had been made in 1604 by his father, after the model of an instrument in the possession of an Italian. This instrument bore the date of 1590.38"[18]

As many Italians were in the Netherlands fighting the Spanish, some with experience in grinding lenses for optical uses, it is likely a few carried with them optical transits such as the one dated to 1590 made in Italy which were so common as to be taken for granted by historians, modifiable into telescopes.[18]


U.S. National Geodetic Survey technicians observing with a 0.2 arcsecond (≈ 0.001 Milliradian (mrad) or 1 µrad) resolution Wild T3 theodolite mounted on an observing stand. Photo was taken during an Arctic field party (c. 1950). Credit: NOAA.
Eight-inch theodolite is from circa 1898. Credit: William Bullock Clark, State Geologist.
Exploration theodolite is shown. Credit: Rama.

The first occurrence of the word "theodolite" is found in the surveying textbook A geometric practice named Pantometria (1571) by Leonard Digges, which was published posthumously by his son, Thomas Digges.[19]

The first instrument more like a true theodolite was likely the one built by Joshua Habermel in Germany in 1576, complete with compass and tripod.[20]

Armillary spheres[edit]

An armillary sphere is shown in a painting by Sandro Botticelli, c. 1480. Credit: Creator: Sandro Botticelli.
This armillary sphere is dated from 1547. Credit: Mike Peel.
This armillary sphere is dated to 1624. Credit: Mike Peel.
This armillary sphere is dated to 1764. Credit: Jorge Royan.

Although lost to Europe since the terminus of the Greco-Roman era, Gerbert reintroduced the astronomical armillary sphere to Latin Europe via Al-Andalus in the late 10th century.[21][22]

Richer wrote about another of Gerbert's last armillary sphere, which had sighting tubes fixed on the axis of the hollow sphere that could observe the constellations, the forms of which he hung on iron and copper wires.[22] This armillary sphere was also described by Gerbert in a letter to his colleague Constantine.[22] Gerbert instructed Constantine that, if doubtful of the position of the pole star, he should fix the sighting tube of the armillary sphere into position to view the star he suspected was it, and if the star did not move out of sight, it was thus the pole star.[22] Furthermore, Gerbert instructed Constantine that the north pole could be measured with the upper and lower sighting tubes, the Arctic Circle through another tube, the Tropic of Cancer through another tube, the equator through another tube, and the Tropic of Capricorn through another tube.[22]

The first two images at the right dating from 1480 and 1547 show the sphere without sighting tubes or any device for observing astronomical objects.

The first two images at the left show spheres dating to after 1608 and the Dutch invention of the telescope.

It appears to be the case that armillary spheres are often displayed without any attachment for viewing such as a sighting tube or telescope.

Of the some 458 images of armillary spheres in commons, only the Vasari painting shows a sighting tube or telescope of any kind within or attached to the sphere.

Sighting tubes[edit]

The Royal Engineers signalling team, using a telescope and a Lucas Lamp, at work at a signalling station at Neuville-Vitasse, 29 April 1917. Credit: John Warwick Brooke.{{free media}}
An Astronomer with Astrolabe and a sighting tube rather than a telescope. Credit: W.B. Rye.{{free media}}
Observation tube is at the Museo Galileo - Istituto e Museo di Storia della Scienza. Credit: Brunelleschi.{{fairuse}}

On the use of the sighting tube to fix the position of the pole star, Shen Kuo wrote:

Before Han times it was believed that the pole star was in the center of the sky, so it was called Jixing (Summit star). Zi Geng(-zhi) found out with the help of the sighting tube that the point in the sky which really does not move was a little more than 1 degree away from the summit star. In the Xining reign-period (1068-1077) I accepted the order of the emperor to take charge of the Bureau of the Calendar. I then tried to find the true pole by means of the tube. On the very first night I noticed that the star which could be seen through the tube moved after a while outside the field of view. I realized, therefore, that the tube was too small, so I increased the size of the tube by stages. After three months' trials I adjusted it so that the star would go round and round within the field of view without disappearing. In this way I found that the pole star was distant from the true pole somewhat more than 3 degrees. We used to make the diagrams of the field, plotting the positions of the star from the time when it entered the field of view, observing after nightfall, at midnight, and early in the morning before dawn. Two hundred of such diagrams showed that the 'pole star' was really a circumpolar star. And this I stated in my detailed report to the emperor.[23]

On the left is an image showing a small telescope. Note the cylindrical pieces needed to accommodate lenses and tube movement. In the drawing on the right from the 13th century an astronomer holds a sighting tube. The tube is only one continuous cylinder.

The second image down on the left shows a tapered metal observation tube with end pieces similar to lens holders.


This is a diagram that shows the operational principles of the dioptra. Credit: Nerijp.

A dioptra [the image at the right] is a classical astronomical and surveying instrument, dating from the 3rd century BCE. The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand. If fitted with protractors, it could be used to measure angles.

Greek astronomers used the dioptra to measure the positions of stars; both Euclid and Geminus refer to the dioptra in their astronomical works.

Camera obscura[edit]

Girolamo Cardano (1501-1576) made "a camera obscura with a diverting spectacle ... appears ... to have initiated the use of a convex lens in the aperture."[24]


"There are indeed ancient tablets that mention astronomers' lenses supported by a golden tube to enlarge the pupil, and in Nineveh a rock crystal lens was found (Pettinato 1998). Maybe one day a new archaeological excavation will find a Babylonian telescope for the first time."[25]


This is an image of a sceptre with an armillary sphere on top. Credit: Lumastan.
The image shows Charlemagne holding a sceptre dated from before 1380. Credit: Siren-Com.
The painting contains a scepter, or walking stick. Credit: Bartolomeo Montagna.
The statue contains a scepter at its right side. Credit: Marie-Lan Nguyen.
An oil painting shows a scepter or sword-like support. Credit: Attributed to Lucas van Leyden.
Here the scepter appears to be more sword-like yet closer to a walking stick. Credit: Adam Eisheimer.
The statue holds a short scepter in its right hand. Credit: Robert Aichinger.

The sceptre imaged at the right is a piece of the Portuguese crown jewels. Note that the image is vertical as is the sceptre.

The image at the left shows a sceptre dated to before 1380.

A key point is that the sceptres both display an object setting above and removed from the shaft of the septre which is either tapered or cylindrical.

The object in the Uranus/Saturn painting from about 1560 does not have an object displayed on top of the sceptre but shows an object closely resembling an objective lens inside its housing.

The second image on the right shows that earlier scepters, or perhaps walking sticks were lengthy, approximately two-thirds a person's height. The ornamentation at the scepters upper end varied greatly as the sculpture at the second left shows.

More recent scepters such as the one shown at third right and third left are sword-like.

The fourth image at the right demonstrates that scepters may be much shorter. The scepter is in the statue's right hand.


The image shows a multi spindle lathe. Credit: Dispossessed1974.{{free media}}

In machine tools, a spindle is a rotating axis of the machine, which often has a shaft at its heart. The shaft itself is called a spindle, but also, in shop-floor practice, the word often is used metonymically to refer to the entire rotary unit, including not only the shaft itself, but its bearings and anything attached to it (chuck, etc.).


Jesuits move Pope Leo X forward against Martin Luther. Credit: unknown, INTERFOTO / History photograph.
This is the torch behind Leo X. Credit: unknown, INTERFOTO / History.
A painting from the second half of the 16th century shows a torch on the right. Credit: Orazio Samacchini (1532-1577).
This is a cropping to only the torch of Commons File:Michele Rocca - Angelica and Medoro - Walters 37414.jpg. Credit: Michele Rocca.
This is a cropping of the torch of Eros from 4th century BC. Credit: unknown, the photo is by Marie-Lan Nguyen (Jastrow), 2008-04-13.
This is a cropping showing a torch from a 16th-century oil on canvas painting. Credit: unknown, Artgate Fondazione Cariplo as mentioned on Commons.
This is a cropping of the torch carried by a winged being in File:Titian - Pietà - WGA22851.jpg at Commons. Credit: Titian (1490–1576).

On the right is a photograph of an apparently 16th century artwork which shows a blazing torch immediately behind the Pope.

The torch painted in second image down the right is much longer and narrower than the one higher or lower on the left.

The second image down on the left shows only the torch from Michele Rocca's "Angelica and Medoro" dated to "between circa 1720 and circa 1750".


"Old Kingdom Egyptian statues from the first to the sixth dynasties had lenses placed in their eyes."[26] "The thickness of the lenses was not intended to duplicate the thickness of the real human eye, but rather to create an effect so that the eye follows the person passing by when looked from other angles."[26] "[T]he illusion of the following eye technique."[26]

The Archaic or Early Dynastic Period of Egypt immediately follows the unification of Lower and Upper Egypt c. 3100 BC. It [is] generally taken to include the First and Second Dynasties, lasting from the Protodynastic Period of Egypt until about 2686 BC, or the beginning of the Old Kingdom.[27]

The eyes of these statues contain rock-crystals. "These are probably the oldest portrait statues in the world. These people who sit before us side by colored to the life, fresh and glowing as the day they gave the artist his last sitting lived at a time when the great pyramids were not yet built and at a date which is variously calculated as from about 4,000 to 6,300 years from the present day. The princess wears her hair precisely as it is still worn in Nubia and her necklace is of a pattern still favored. The eyes of both statues are inserted. The eyeball which is set in an eyelid of bronze, is made of opaque white quartz with an iris of rock-crystal enclosing a pupil of some kind of brilliant metal. This treatment gives to the eyes a look of intelligence which is almost appalling." Amelia B. Edwards "These incomparable statues are most expressive and stand in vitality to the works of any later age in Egypt. They were found in the tomb chamber- Ra-Ho-tep is entitled a royal son [probably of Seneferu]- The signs carved in these tombs are among the earliest known. Instead of full-length burial with coffins, head rests, vases, and provision for a future life, the more usual method of burial at Medum is lying on the left side with the knees drawn up facing the east and without vases or other objects, showing a diversity of beliefs and probably of races." W.M. Flinders Petrie.[28]

"The composition of these eyes is a lens of polished rock crystal (either alpha silica or fused silica, formerly known as cystalline quartz and fused quartz which had a convex front surface and a near hemispherical concave ground pupil surface in a flat iris plane (normally covered with resin) at the rear of the lens."[29]

The Prehistory of Egypt spans the period of earliest human settlement to the beginning of the Early Dynastic Period of Egypt in ca. 3100 BC, starting with King Menes/Narmer.

The Predynastic Period is traditionally equivalent to the Neolithic period, beginning ca. 6000 BC and including the Protodynastic Period (Naqada III).

Early lenses[edit]

This image is a photo of the Nimrud lens in the British museum. Credit: Geni.

"Lens-shaped crystals have long been known from Bronze Age contexts"[30]. These are "usually recognized as short-focus magnifying lenses."[30]

The slightly oval lens [40 x 35 mm] has been roughly ground and has a focal point about 110 millimetres (4.5 in) from the flat side.[31][32]

"There are now 23 ancient lenses on display in the Archaeological Museum at Herakleion and many more are in storage there. They are also made of rock crystal and are of optical quality, with generated plano-convex surfaces."[33]

There is more about lenses more recently from Visby, Gotland. "What intrigues the researchers is that the lenses are of such high quality that they could have been used to make a telescope some 500 years before the first known crude telescopes were constructed in Europe in the last few years of the 16th century."[34] "Made from rock-crystal, the lenses have an accurate shape that betrays the work of a master craftsman. The best example of the lenses measures 50 mm (2 inches) in diameter and 30 mm (1 inch) thick at its centre."[34] "The [Visby] Gotland crystals provide the first evidence that sophisticated lens-making techniques were being used by craftsmen over a 1,000 years ago."[34]

"If one Italian scientist is correct then the telescope was not invented sometime in the 16th century by Dutch spectacle makers, but by ancient Assyrian astronomers nearly three thousand years earlier. According to Professor Giovanni Pettinato of the University of Rome, a rock crystal lens, currently on show in the British museum, could rewrite the history of science. He believes that it could explain why the ancient Assyrians knew so much about astronomy."[34]

Rock crystal lenses
Name (or identification) Discovery period Location Approximate date Source[30] unless noted otherwise
Egyptian lenses IV/V Dynasties Egypt, eyes in funerary statues 2620-2400 BC [35]
Evans lenses (plano-convex) Middle Minoan IIIB Temple Repositories at Knossos, along with a "royal Draught Board" with ivory and crystal inlays backed with silver foil 1640-1600 BC, Minoan civilization A. Evans, The Palace of Minos I (London 1921) 469-72; cf. the eye of the steatite bull's-head rhyton from the Little Palace at Knossos: Evans, The Tomb of the Double Axes etc (London 1914) 82.
"Three bossed crystal discs" (plano-convex) Late Minoan II-IIIA Mavrospelio cemetery 1425-1340 BC E. J. Forsdyke, "The Mavro Spelio Cemetery at Knossos," BSA 28 (1926-1927) 243-96, esp. 288.
Artemision lenses (plano-concave) Archaic levels the Artemision of Ephesos 3300-1200 BC D.G. Hogarth, Excavations at Ephesus: The Archaic Artemisia (London 1908) 210-11, pl. 46.
Schliemann lenses (plano-convex) Troy Troy 1334-1184 BC V. Tolstikov and M. Treister, The Gold of Troy: Searching for Homer's Fabled City (London 1996) nos. 176-216, 230.
Nimrud lens (plano-convex) Neo-Assyrian North West Palace, Room AB 750–710 BC Austen Henry Layard at the Assyrian palace of Nimrud, in modern-day Iraq.[36]
Roman London lens (fragmentary biconvex glass lens of light green color) Roman London Roman London 43-50 AD H. Syer Cuming, "On Spectacles," The Journal of the British Archaeological Association 11 (1855) 144-49.
Pompeii lens (plano-convex) excavations of the Via Stabia "House of the Engraver" 79 AD E. Gerspach, L'art de la verrerie (Paris 1885) 41-42.
four rock-crystal lentoids (plano-convex) the historical period Amathous Temple of Aphrodite M.-E Boussac in P. Aupert and A. Hermary, "Travaux de l'Ecole franlaise i Amathonte en 1979," BCH 104 (1980) 809, fig. 12; Aupert and Hermary, "Amathonte: Rapport préliminaire (1975-1979)," RDAC 1980, 237, pl. 32.6
Sakellarakis lenses (plano-convex) historical period Idaean Cave historical period [33]


  1. The ancients may have used air or aerial telescopes.

See also[edit]


  1. galileo.rice.edu The Galileo Project > Science > The Telescope by Al Van Helden
  2. 2.0 2.1 2.2 Ivan Van Sertima (2010). Ivan Van Sertima, ed. The Lost Sciences of Africa: An Overview, In: Blacks in Science: Ancient and Modern. Pscataway, New Jersey, USA: Transaction Publishers. pp. 5–26. ISBN 978-0-87855-941-1. Retrieved 4 October 2012.
  3. Roger Bacon (14 December 1994). Opus Majus. Astronomy Trek. Retrieved 6 June 2014.
  4. The Viking Sunstone, from Polarization.net. Retrieved February 8, 2007.
  5. Leif K. Karlsen 2003. Secrets of the Viking Navigators. One Earth Press. ISBN 978-0-9721515-0-4 pp. 220
  6. Larry Brown (2005). An early history of the telescope. From 3500 B.C. until about 1900 A.D. Antique Telescopes. Retrieved 8 April 2012.
  7. 7.0 7.1 7.2 Infoserv (15 April 2011). A Brief History of Glass. Artenergy Publishing S.r.l. Retrieved 2014-06-06.
  8. 8.0 8.1 8.2 telescope. San Francisco, California: Wikimedia Foundation, Inc. 25 May 2014. Retrieved 6 June 2014.
  9. AH Tunnacliffe, JG Hirst (1996). Optics. Kent, England. pp. 233–7. ISBN 0-900099-15-1.
  10. 10.0 10.1 The Galileo Project > Science > The Telescope
  11. Henry C. King (2003). The history of the telescope. ISBN 978-0-486-43265-6.
  12. The First Telescopes, In: Cosmic Journey: A History of Scientific Cosmology. Center for History of Physics, a Division of the American Institute of Physics.
  13. A. E. Bell. Ph.D., M.Sc. Christian Huygens and the Development of Science in the Seventeenth Century.
  14. 14.0 14.1 AnonMoos (8 October 2012). Image in Vasari painting. San Francisco, California: Wikimedia Foundation, Inc. Retrieved 8 October 2012.
  15. Asclepias (8 October 2012). Image in Vasari painting. San Francisco, California: Wikimedia Foundation, Inc. Retrieved 16 October 2012.
  16. Ian Ridpath (1 November 2014). Re: Early telescopes. Yahoo!. Retrieved 3 November 2014.
  17. Kevin Johnson (3 November 2014). Re: Early telescopes. Yahoo!. Retrieved 3 November 2014.
  18. 18.0 18.1 Albert Van Helden (June 1977). "The Invention of the Telescope". Transactions of the American Philosophical Society 67 (4): 1-67. https://www.jstor.org/stable/1006276. Retrieved 2018-6-01. 
  19. Daumas, Maurice, Scientific Instruments of the Seventeenth and Eighteenth Centuries and Their Makers, Portman Books, London 1989 ISBN 978-0-7134-0727-3
  20. Geomatica Online |url=https://web.archive.org/web/20071113052943/http://geomatica.it/strumenti_antichi/estratto.htm |date=13 November 2007 }} Colombo, Luigi, Selvini, Attilio, Sintesi di una storia degli strumenti per la misura topografica
  21. S. Jim Tester (1987). A History of Western Astrology. Rochester: Boydell & Brewer. ISBN 0-85115-446-8.
  22. 22.0 22.1 22.2 22.3 22.4 Oscar G. Darlington (1947). "Gerbert, the Teacher". American Historical Review 52 (3): 456–76. 
  23. Needham, Joseph (1986). Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Taipei: Caves Books, Ltd.
  24. Paul T. Burns (1990). The History of The Discovery of Cinematography - 1400 - 1599. Planetel Communications. Retrieved 8 October 2012.
  25. Giulio Magli (2009). When the method is lacking, In: Mysteries and Discoveries of Archaeoastronomy from Giza to Easter Island (PDF). Rome, Italy: Copernicus Books. pp. 97–116. doi:10.1007/978-0-387-76566-2_5. ISBN 978-0-387-76564-8. Retrieved 15 October 2011.
  26. 26.0 26.1 26.2 Koot van Wyk (8 July 2010). Lenses and Telescopes in the Ancient Near East and the Bible. Retrieved 4 October 2012.
  27. Ian Shaw, ed. (2000). The Oxford History of Ancient Egypt. Oxford University Press. p. 479. ISBN 0-19-815034-2.
  28. File:Prince Ra-Hotep and Princess Nefer-T (cropped).jpg. San Francisco, California: Wikimedia Foundation, Inc. 22 December 2011. Retrieved 4 October 2012.
  29. Al Berens (2001). Remarkable Old Kingdom Lenses and the Illusion of the Following Eye. Comcast. Retrieved 4 October 2012.
  30. 30.0 30.1 30.2 Dimitris Plantzos (July 1997). "Crystals and Lenses in the Graeco-Roman World". American Journal of Archaeology 101 (3): 451-64. http://www.hist-arch.uoi.gr/prosopiko/plantzos/Crystals.pdf. Retrieved 2011-10-17. 
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Further reading[edit]

External links[edit]

{{Radiation astronomy resources}}