The Developmental History of the Telescope

Wooden telescope painted with red lacquer with gold and black decorations. The tube in 7 segments can be taken apart, 4.2 meters long, Pielro Beltrami, Milan, 1752 (notice the wonderful Dolomite Mountains in the background as this photo was taken in the cloister of the museum), © Luxottica Museum, Agordo
Wooden telescope painted with red lacquer with gold and black decorations. The tube in 7 segments can be taken apart, 4.2 meters long, Pielro Beltrami, Milan, 1752 (notice the wonderful Dolomite Mountains in the background as this photo was taken in the cloister of the museum), © Luxottica Museum, Agordo
Binocular telescope, made by Capuchin friar Chérubin d'Orléans, length 105 cm, four telescoping sections containing two small telescopes, wood painted black on the inside, largest section covered by black shagreen, about 15X magnification, © Institute and Museum of the History of Science, Florence
Binocular telescope, made by Capuchin friar Chérubin d'Orléans, length 105 cm, four telescoping sections containing two small telescopes, wood painted black on the inside, largest section covered by black shagreen, about 15X magnification, © Institute and Museum of the History of Science, Florence (Move your cursor over the left and then the right for two different detail images.)
José Ribera (1591-1652), El sentido de la vista (The Sense of the View), mid 17th century, Museo Franz Mayer, Mexico City, México
José Ribera (1591-1652), El sentido de la vista (The Sense of the View), mid 17th century, Museo Franz Mayer, Mexico City, México. (Move your cursor over the left and then the right for two different detail images.)
Refracting telescope, 3 drawtubes and a main tube, 30 cm length, 57 mm diameter, sculpted turned Ivory, tapering towards the eyepiece end, objective glass present, 17th century, M423, from the former Mensing Collection, © The Adler Planetarium and Astronomy Museum, Chicago  Unique
Refracting telescope, 3 drawtubes and a main tube, 30 cm length, 57 mm diameter, sculpted turned Ivory, tapering towards the eyepiece end, objective glass present, 17th century, M423, from the former Mensing Collection, © The Adler Planetarium and Astronomy Museum, Chicago Unique
Five draw, paper covered Galilean telescope with equal diameter ferrules, extended length 92.7 cm, main barrel diameter 4.8 cm, objective aperture 1.6 cm, magnification 16X. Made in Augsburg, Germany before August 1, 1617, Italian lenses, gilded borders, Decorative Arts Museum, Berlin   This was part of a collection of 17th Century scientific instruments found in a finely crafted cabinet built for a royal family to display scientific instruments--a kunstschrank, the so-called Pommeranian Cabinet, Kunstgewerbemuseum.
Five draw, paper covered Galilean telescope with equal diameter ferrules, extended length 92.7 cm, main barrel diameter 4.8 cm, objective aperture 1.6 cm, magnification 16X. Made in Augsburg, Germany before August 1, 1617, Italian lenses, gilded borders, Decorative Arts Museum, Berlin This was part of a collection of 17th Century scientific instruments found in a finely crafted cabinet built for a royal family to display scientific instruments--a kunstschrank, the so-called Pommeranian Cabinet, Kunstgewerbemuseum.

 

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This webpage was a major undertaking which has now been accomplished with the kind assistance of a very large group of educators and collectors worldwide. I am especially grateful for the strong support of Marvin Bolt, Jean Marie Devriendt, Jay Enoch, Jay Galst, Robert Hafner, Albert Van Helden, Vincent Ilardi (recently deceased), Peter Louwman, Eugene Rudd, Gerogio Strano, Alexis Vanlathem, and Rolf Willach. The staff of the following institutions were also particularly helpful - Adler Planetarium (Chicago), British Museum (London), Institute and Museum of the History of Science (Florence), Luxottica Museum (Agordo), and the Royal Observatory (Greenwich). They all have contributed to the significant knowledge presented here and we are going to make a difference.

The Slideshows (1-13)  

  1. Some of the Earliest Known Telescopes
    Marv Bolt (Adler Planetarium) and Michael Korey (Mathematisch-Physikalischer Salon, Dresden) are doing critical and fundamental work on the earliest telescopes in the world. This research has been supported by their own institutions and several government granting agencies. They have located almost twenty “candidates” and a paper is to be published in a volume of the Dutch Academy of Sciences. Afterwards an educational website will be created. All of this is exciting news. We look forward to their results and will certainly link to this important website once it is live. Meanwhile here are just some of the known examples for you to enjoy.
  2. Other 17th Century Instruments
  3. Historic Models and Other Recent Examples
  4. Walking Canes With Telescopes
  5. Small Telescopes (Spyglasses)
  6. Colorful Artwork
  7. Other Printed Artwork
  8. Sculptured Works of Art (Two slideshows)
  9. Represented on Stamps (Two slideshows)
  10. Represented on Medals (Two slideshows)

A. The Overview

The world is currently celebrating the 400 year anniversary of the invention of the telescope. Activities began last September 2008 in Middelburg, the Netherlands and they will continue throughout 2009. Our educational website therefore has the special opportunity to acknowledge the years 1608-1609 when the telescope, a two-lens device for seeing at a distance, became yet the third adaptation of the optical lens. The simple magnifying glass was appreciated as the first optical aid sometime soon after the first millennium. Spectacles (or eyeglasses) were the second adaptation near the end of the 13th century.

The story of the telescope and other optical instruments actually had their origin much earlier. The reader is now invited to review a portion of that great journey...the one which began with the evolution of the optical lens thousands of years ago in Antiquity.

B. Prehistory of the Optical Lens and its Craft

It is generally believed that over 3,000 years ago in Northern Mesopotamia people began placing ceramic items/pots into early high temperature kilns. Those objects were occasionally decorated with some form of glaze material. Everyone enjoyed the effect that was achieved so these pottery glazes likely became known as the first glass-like products. Thus began the long cycle of glass development. As the technology evolved, the quality and clarity of glass products improved over many centuries.

Natural glass was also first discovered several thousand years ago. This rock crystal (quartz) may have been recognized even earlier but we will likely never know. A group of interesting objects have been located over the last few hundred years which reveal that people were grinding and even polishing this natural material long ago. This was fairly expensive, quite difficult and time-consuming to grind, however, some relatively transparent quartz pieces were able to be reformed into various useful shapes. The first lenses may have been in Egypt about 2600 B.C. as parts of schematic eye structures (iris/pupil inserts) associated with funerary statues. A convex front surface (like our human cornea) is noted as well as a ground flat rear surface covered with pigment to appear much like the human iris (forming our human pupil). Examples exist at the Egyptian Museum in Cairo and at the Louvre in Paris.

Convex lenses were mentioned by the Greek playwright Aristophanes in 423 B.C. in his comedy play The Clouds. Socrates and a friend have some dialogue regarding “burning glass” used by people of those times to start fires. It has been written that the military use of metal mirrors and also soldier’s shields was recognized by Archimedes (287-212 B.C.). They could cause “Greek Fire” by concentrating the sun’s rays causing the Roman fleet, commanded by Marcellus, to burn in the battle of Syracuse. However Dennis Simms et al explained recently why the concept of ignition by radiation was incorrect.

Lucius Seneca the Younger (4 B.C. – c. 65 A.D.) was the very first person to actually discuss magnification effects produced by concave mirrors and also by biconvex globular flasks filled with water (calling it a lens is probably an anachronism). In his book, Naturales Quaestiones, he wrote, “I would like to add that everything appears much larger when seen through water; any small and blurred letter can be seen larger and clearer when viewed through a glass vessel filled with water.” The first man to call a lens a lens was a Muslim precursor of Ibn al-Haytham.

Images of some particularly noteworthy objects are shared on one of the attached slideshows. These were most likely used for decorative or adornment purposes, like jewels or attachments similar to lovely embellishments in fashion. The Nimrud Lens (900-700 B.C.), found in 1853 during excavations of the Assyrian town of Nineveh may possibly be one of the oldest known optical glass artifacts. The Lothar Crystal (855-869 A.D.), made in Metz, France for the Carolingian King Lothar II, is also an important optical treasure. The Visby Lenses from Gotland have been recognized for their history and the likelihood that they originated in Persia. These lenses have truly remarkable fine image qualities with very little spherical aberration. All of the objects mentioned above have been studied fairly extensively. Some polished glass objects extracted from Anglo-Saxon graves are also made of natural rock crystal. Curved rock glass crystals shaped like reading stones cover liturgical art objects (martyr’s relics) in reliquaries like the Cathedrals of Halberstadt and Hildescheim, both in Germany. These objects were all made using a simple archaic technique on a crude hand-turned rotating plate surface. They were most likely handled by stone-grinders and perhaps also later by monks in the workshops of monasteries. Some of these rare objects have been critically analyzed by optical engineer Rolf Willach and they are described in his recent book, Long Road to the Invention to the Telescope. Some other museums hold lens-like artifacts made in antiquity, and which were created from ground and polished rock. It is quite interesting to learn about this glass material and the crude method used to resurfacing it.

C. Significant Events after the Beginning of the Second Millennium

Most people know that Alhazen dealt with optics extensively. Around the year 995 he wrote, “a segment of crystal sphere makes objects appear bigger.” In his 11th century work Opticae Thesaurus, he wrote about vision, reflection, and refraction. He showed that the source of light was not from within the eye but instead it was from each point on an illuminated object (outside of the eye). He commented that glass altered any light that traveled through it. The convex lens was probably first known and used as a very crude magnifier at this time. Then in the early 13th century, the works of Ptolemy and Alhazen were translated from Arabic into Latin so that more people with scientific minds could understand the basic principles. Alhazen had commented on the enlarging effect produced by spherical plano-convex lenses. These lenses were known as the early reading stones of the 12th century. In the mid 13th century Roger Bacon confirmed that segments of spheres made letters and small objects appear larger when he wrote; “for this reason such an instrument is useful to old persons and those with weak sight, for they can see any letter, however small, if magnified enough.” Bacon must have been one of the first people to truly understand that the plano-convex glass segment (the crude reading stone) had potential as a visual aid. Bacon knew even of Seneca's observation and he realized that there was a possibility of an aid to the elderly in that observation, though he never made the step himself.

Man-made glass also originated in ancient times and the craft of producing it improved slowly over the centuries. Eventually this evolved during the first couple hundred years of the second millennium into the cottage industry centered around Venice and also in the Tuscany region. Aside from the artisans, monks also worked with optical glass. Further refinement led to crude magnifiers with simple handles. Perhaps some unknown artisan, who had worked with glass near Pisa, began to experiment with two single magnifiers (dioptrical vision aids). He placed a metal rivet through the ends of their handles which gave birth to the world’s first pair of eyeglasses (rivet spectacles). The idea traveled back to Venice (and the island of Murano) where it was immediately incorporated into the glass maker's industry.

Primary source documentation exists from two friars who lived in the Dominican Monastery of St. Catherine of Alexandria in Pisa, Italy. Father Giordano da Rivalto announced the discovery from a pulpit February 23, 1306. It was also mentioned in the 1313 obituary notice of Father Alessandro della Spina, both instances pointing back to circa 1286-87 as the time period of importance. The name of the true inventor of eyeglasses remains lost in obscurity yet it was a simple but ingenious idea.

It can now be assumed furthermore that manufactured glass lenses were made in quantity for eyeglasses and they probably came from pear-shaped bubbles of blown glass. Glassblowing had been invented during the 1st century B.C. by the glassmakers of Syria but this was a creative idea. Pairs of similar circular blanks could be stamped out and then ground on the concave side (inner surface) to create similar plano-convex lenses, leaving the outer convex surface undisturbed. This grinding and polishing was done on flat rotating plates of iron or copper. The lenses produced were of poor optical quality because of various sized bubbles, tiny particulate matter, a color tinge (most often green from large amounts of iron) and even stria. These findings have been confirmed by Rolf Willach following his scientific study of nearly all of the earliest rivet spectacle lenses known.

There was a lot of secrecy surrounding glass production by the Venetian guilds. Even independent artisans did not share their secrets of grinding and polishing. All this was guarded and hardly anything was recorded. Then the archives of existing information in Venice were mostly destroyed in the 19th century and only in Florence did tens of thousands of archival documents survive to modern times. Much of this was meticulously analyzed by the late Vincent Ilardi for his Renaissance Vision from Spectacles to the Telescope. The pre-eminence of Florence in the production of eyeglasses for presbyopes (older far-sighted people) and myopes (younger near-sighted people) was documented and firmly established.

Monks who worked with optical glass were soon replaced by a group of artisans who became the ancestors of our modern opticians. Concave lenses did not become widely available until the middle part of the 15th century. The availability of printed books after 1450 increased the demand for vision aids exponentially, leading to the birth of a new industry. The Middelburg Glass Factory was established in 1581 and it was the oldest in The Netherlands. Eyeglasses appeared in The Netherlands soon after they were produced in Germany (Nuremberg, Regensburg, and later Furth and Augsburg) where the first real industry of the world started. There it was even governed by a rigid set of rules and regulations.* Molds were used to create magnifiers, glass lenses and their copper wire frames, but again the quality left much to be desired. After 1500 or so both sides of the lenses were ground and the quality of the lenses improved somewhat but craft skills required for making particularly fine lenses was lost in the mass-production.

*The Regensburg and Nuremberg Regulations will be the topic of a future major webpage because they are extremely rare and important, representing the world’s first eyeglass catalogues.

D. Leading up to the Telescope Patent Application

Empty long tubes were used in Antiquity to screen out disturbing side light, therefore creating the equivalent of a lens-less telescope. Unfortunately, this did not increase visual efficiency when people were trying to observe the stars because there was no magnification.

Glass-making and lens-grinding had been improving in the later part of the 16th century. The idea probably occurred to some people to try to arrange more than one lens in a telescope-like fashion in order to produce some beneficial result. The most desired effect was a sharp magnified image. The invention of the telescope became a challenge for both the glass and the spectacle maker. How it first occurred is unknown but magnification was noted when a strong minus (diverging) lens was aligned with a weaker plus (converging) lens. Presumably different combinations were tried and the distance between the lenses recorded. It must have been tedious, but finally two lenses were placed together, a certain distance from each other, and then installed into an empty cylindrical tube. Shortly after the year 1600, this new instrument allowed distant objects to be seen closer and clearer. It must have been an exciting discovery to anyone viewing through this device for the very first time.

Early lens grinding resulted in lenses where the periphery was not satisfactory, especially for the telescope. The object lens of a telescope required greater accuracy across its entire aperture when compared to the normal spectacle lens. Telescopes crafted to accommodate some of the finest large lenses already in existence had to be trumpet-shaped with a large flare on one end. This trumpet shape allowed the placement of the diaphragm which cut off the outer zone of the lens. The other choice was to chip off the outer zone.

In the camera obscura at the very end of the 16th century it was found that the introduction of a diaphragm improved the image by blocking out the peripheral distortion. The lenses in the camera obscura were also spectacle lenses. Therefore, it is not impossible to assume that the idea of the diaphragm for the telescope may have been derived from the camera obscura. The lenses had to be either stopped down (restricted) by use of a diaphragm or they had to be cut down to a smaller size (usually by chipping little pieces off the periphery). Without improved lenses or the use of a diaphragm the telescope cannot function most efficiently. Thus, by trial and error, the lens makers were able to reduce the aperture using a paper diaphragm until a much improved optical image was achieved. About three hundred years after spectacles were first used, the significant clarity required of the earliest lenses in telescopes was finally attained.

Probably sometime during the 1590s, in the Dutch coastal town of Middleburg, the first telescope utilizing a plus (converging) and a minus lens (diverging) was created. Two local individuals, spectacle peddler Zacharias Janssen and spectacle maker Johannes Lipperhey, independent of each other, may have developed the new instrument to view things like stars at a distance. Lipperhey presented his spyglass to Dutch leader Prince Maurice, Duke of Nassau on September 25, 1608. He applied for a patent from the States-General in The Hague (the Committee of Counselors of the States of Zeeland) on October 2, 1608. Lipperhey’s telescope consisted of a convex (converging) lens combined with a concave (diverging) lens probably placed about a foot apart and this gave an erect unreversed image. He was then invited to The Hague to demonstrate his refracting telescope. After climbing a tower, observers were delighted to see the windows of St. Peter’s Church in Leiden and the clock of the Old Church in Delft, using this new tool. It caused a sensation and Maurice saw it as an important military tool for spying on enemy troops. Twelve days later another individual (possibly Zacharias Jansen) came before the Committee to demonstrate his instrument. Three days later, Jacob Metius of Alkmaar, also applied for a patent. Basic telescopes with two lenses in a cylindrical tube started to appear all over The Netherlands, so the States General decided to reject both of the formal patent applications. The reason was a sensible one; this novel gadget to magnify the heavens was too easy to copy and it could already have been known to others.

Leonard Digges and his son, Thomas, have been credited with the invention of a reflecting telescope (a convex lens and a mirror), predating Lipperhey’s refractor by more than 30 years. In Venice in 1538, Girolamo Fracastoro had written for the first time about a twin-lens telescopic arrangement. The distinction as the inventor of the telescope was claimed by others. The list includes Giovanni Battista della Porta of Naples, Englishman William Bourne, Raphael Gualterotti of Florence, and possibly even Juan Roget of Burgundy near Gerona, Spain. Who specifically can claim the title of inventor of the telescope therefore remains unknown. All of the authors of articles on this subject agree, however, that Hans Lipperhey was the first person to demonstrate a working model and also apply for a patent. Therefore two statements have the agreement of nearly everyone. The region in and around Middelburg is where all of this exciting activity took place. Hans Lipperhey has the honored title of inventor of the telescope.

E. Galileo and the Telescope

There evidently was a competitive atmosphere surrounding the introduction of the telescope. Although printed news about this two-lensed tube that made far-away objects appear bigger and closer was relatively sparse, verbal reports spread rapidly across Europe. Its significance was immediately recognized. Galileo Galilei, professor of Mathematical Sciences at the University of Padua, Italy conducted scholarly experiments and then crafted his own 3X magnification telescope in the early summer of 1609. He made further refinements in August 1609 and presented an 8X instrument to the Doge and the Venetian Senate in the bell tower of San Marco. Galileo gradually improved the power of his telescope by grinding lenses himself and was able to begin studying the craters of the moon. In November 1609 he built a superior telescope with almost 30X magnification and made additional major discoveries. In January 1610 the observations found that Jupiter had at least four satellites of its own, that sunspots exist and that Venus has phases.

Galileo desired recognition for his discoveries and insights so he published (in Latin) the scientific story of his telescope in the Sidereus Nuncius (Starry Messenger) in March 1610. This book was dedicated to Cosimo de' Medici and it included the first illustrations of the heavens (The Milky Way) and especially our own moon. The idea that the moon had a mountainous and cratered surface and was not perfectly spherical was proven by the use of his telescope. The book also contains the results of Galileo's early observations of the Moon, the stars and Jupiter’s moons.

Around this time, the telescope also became useful as permanent equipment for certain officers in the military, mariners, and even for those explorers leading expeditions. Only a few years after its invention, the telescope had become the most important tool for astronomers. Philosopher Descartes claimed it was one of the major inventions of his time.

Galileo had taught himself the arduous task of how to grind and polish lenses. Spectacle makers in Venice and Florence polished their lenses using a rotating felt or deer leather which led to aspherical deformation. More than 95% of the lenses Galileo looked at were of poor quality. By 1616 he was able of use only three out of about 300 spectacle lenses for a terrestrial telescope and not a single lens was adequate for an astronomical telescope.

It was clear that Galileo’s observations only made sense if there was a sun-centered galaxy. Up until this time, an earth-centered universe theory was believed by most. Galileo’s idea was not original because this concept had been introduced earlier as a revolutionary proposed in Copernicus' De revolutionibus, published in 1543. It directly opposed the general belief most strongly supported by the Church. Thus, Galileo was charged with heresy by the powerful 1633 Inquisition in Rome. Galileo’s ideas were condemned by the Church and he was forced to publicly recant his conclusions. Some of his publications were even added to the list of prohibited books and he was placed under house arrest until his death in 1642. Today, we know he was correct and near the end of 2008 the Vatican reversed its position by honoring Galileo.

Galileo’s sight began to deteriorate at age sixty-eight while he was under house arrest. By June 1637 he had lost the total use of his right eye; his left eye, meanwhile, was affected by a constant discharge and he described seeing a “luminous halo” around candle flames (possibly caused by a cataract or some macula degeneration). By December 1637 he was completely blind and wrote to a friend: “The noblest eye is darkened which nature ever made, an eye so privileged and so gifted with rare qualities that it may with truth be said to have seen more than the eyes of all those who are gone, and to have opened the eyes of all those who are to come (Quotation from an upcoming book by Jay Galst).”  Modern speculation is that Galileo suffered from iridocyclitis secondary to rheumatoid arthritis and that this might have led to secondary cataract and, possibly, glaucoma. It is highly unlikely that gazing at the sun was the cause of his blindness. (Blodi, F.C., 1986, 'The Eye, Vision and Ophthalmology on Postage Stamps', in Hirschberg's History of Ophthalmology Vol 11 (Part Two), Wayenborgh, Bonn, pages B169-B170).

Galileo’s telescope slowly lost favor because of the restricted field of view, a direct result of increasing the magnification progressively. The limited field of view made performance less than satisfactory and almost impractical for military purposes. As a result of this the Keplerian (astronomical) telescope, which had a much larger and brighter field of view, was developed and in the 1630’s it replaced the Galilean style. Other 17th century changes included the addition of erectors and compound eyepieces, which turned the image upright again. Perfect spherical curvature and much higher polish became the norm while clarity of the glass also improved. Reflecting telescopes came into use after the 1670s because of the work of Isaac Newton. Additional changes met with even greater success in the following century when achromatic lenses, brass tubes, and mounting represented other improvements to this scientific instrument.

F. Other Significant 17th Century People and some of their Contributions to the Telescope

Guiseppi Campani (1635-1715) Italy - optician, a perfectionist, a craftsman who made the finest and most outstanding telescopes of his time in Europe. In 1663-4, he invented or developed a compound eyepiece (with three lenses) that established him as the outstanding optician of the day.

Prince Federico Cesi (1585-1630) Italy - was founder of the Accademia dei Lincei, and in 1611 at a banquet in Galileo’s honor he proposed calling the Galileo instrument "telescopio" [from the Greek tele (far) and scopeo (I see)]. The telescope enlarges the size of a distant object.

Eustachio Divini (1610-1685) Italy - made very fine telescopes and microscopes, a superb craftsman.

Francesco Fontana (1580-1656) Italy - lawyer and astronomer who made the finest telescopes. He created woodcuts showing the Moon and the planets as he saw them through a self-constructed telescope. The lunar crater Fontana and the crater Fontana on Mars are named in his honor

Pierre Gassendi (1592-1655) France - became the first person ever in 1631 to observe the transit of a Mercury across the Sun, which Kepler had predicted. Later that same year, he watched for the transit of Venus, but this event occurred when it was night time in Paris.

James Gregory (1638-1675) Scotland - mathematician and astronomer – in 1663 he proposed the design of a Gregorian reflecting telescope using mirrors which produced erect images. Of the British mathematicians of the seventeenth century, Gregory was only excelled by Newton”

Thomas Harriot (1560-1621) England – credited with the creation of the first ever drawings of the celestial moon after peering through a 6X telescope in late July 1609, a few months before Galileo.

Johannes Hevelius (1611-1687) Germany/Poland - built an observatory in his home in 1647 and used an astronomical telescope. He also devised a lens-polishing machine. He claimed to have invented the polemoscope' (side-looking opera or field glass with an oblique mirror) in 1637. He described this in his book which included a map representation of the moon, Selenographia (1647). By the early 1670s he had built a 140-foot telescope.

Christiaan Huygens (1629-1695) Holland - astronomer who discovered Saturn's moon Titan in 1655. In 1657 he explained the flat ring around Saturn. His telescope lens is all that remains of the 123 foot long 100X magnification instrument he used, designed and constructed in collaboration with his brother, Constantijn Huygens. In the mid-1650s Huygens had devised a new way to grind and polish lenses.

Johannes Kepler (1571-1630) Germany – Highly accomplished mathematician who constructed the first astronomical telescope at the beginning of the 17th century consisting of a convex objective and a convex ocular. He also suggested using a two lens (both convex) eyepiece to re-invert the image. Published his Dioptrice in 1611. A major contribution to optics in 1604 was the correct understanding of the optical functioning of the human eye. He published his first two laws of planetary motion in 1609 (Astronomia nova), and he added the third one in 1619 (Harmonices mundi).

Carlo Antonio Manzini (1599-1677/78) Italy - an astronomer and mathematician. L'occhiale all'occhio, dioptrica practica, 1660, is one of the oldest accounts of the techniques for grinding and polishing glass lenses. The crater Manzinus on the Moon is named after him.

Simon Marius (1573-1624) Germany - Astronomer, published in 1614 his work Mundus lovialis describing the planet Jupiter and its moons. He claimed to have discovered the planet's four major moons some days before Galileo. This led to a dispute with Galileo. It is possible that Marius discovered the moons independently, but at least some days later than Galileo.

John Marshall (1659-1723) England - Optician who was was given the approbation of the Royal Society in 1693, and became spectacle maker to George I in 1715. Most important, his modification of the method described by Della Porta and William Bourne produced batches of good lenses of the prescribed dioptre. Instruments by Marshall are also quite scarce.

Isaac Newton (1642-1727) England - Highly accomplished mathematician who designed a reflecting telescope in 1668. He developed a telescope using a parabolic mirror similar to Bacon’s “burning mirror” of 1267. His 1704 Opticks or a treatise of the reflections, refractions, inflections and colours of light, was the Seminole text on the subject. He published a celebrated paper on light and colors, demonstrating that white light is a mixture of colored light, each having its own degree of refraction (wave length).

Cherubin d’Orleans (1613-1697) France - Capuchin monk who constructed the first binocular telescopes between 1665 and 1679 using optical glass – he also devised a pendulum lens-polishing machine

Schyrl de Rheita (1597-1660) Czechoslovakia / Austria - a Capuchin monk who became a founder of technical optics – he published a book Oculus in 1645, proposing a highly improved method of polishing lenses, also the improvement offered by a three-lens terrestrial eyepiece. He discovered the bands on Jupiter with a self-made binocular telescope. His work led to the development of the four (convex) lens eyepiece. He also was the one who introduced the terms objective and ocular. He was the maker of Kepler’s telescope.

Christopher Scheiner (1573-1650) Germany - a brilliant geometer, physicist and astronomer. He published many scientific works especially Rosa Ursina in 1630. He discovered sunspots independently of Galileo and explained the elliptical form of the sun near the horizon as the effect of refraction. In his Oculus (1619) he showed that the retina is the seat of vision. He started using eyepieces with two lenses in the early 1630s and was the first to design the helioscope, an instrument used to observe the sun.

Geronimo Sirturus (1579-1631) Italy - a Jesuit father who published the remarkable book Telecopium…. in 1618 where he discussed the Dutch telescope and spectacle lenses. It is the oldest known written instructions for manufacturing telescopes. His famous drawing shows the arrangement of lenses in a telescope. Sirturus pointed out that a workman had to be most careful in polishing otherwise the lens became lopsided or aspherical with peripheral distortion. The goal had to be a lens with perfectly spherical surfaces. He may have also invented the method of the spherical grinding of moulds. Lens grinding and polishing techniques improved dramatically.

Evangelista Torricelli (1608-1647) Italy - known for making high quality objective lenses and also the finest telescopes. He is also highly recognized for inventing the barometer. After Galileo died in 1642 Torricelli succeeded him as professor of philosophy and mathematics at the Florentine Academy.

Johannes Wiesel (1583-1662) Germany - a founder of technical optics – the first professional optician in Europe, he improved resolving power of the telescope – two of his telescopes now survive (both in an incomplete state), at Skokloster Castle in Sweden. (reversed tapered, inverted shape). A third one, signed by this Augsburg Optician, has been fully evaluated by Rolf Willach.

G. Summary and Conclusion

Optical science is ancient. Glass objects were first recognized several thousand years ago. In the 13th century it was already known that lentil-shaped pieces of glass altered light and also magnified objects. By the beginning of the 17th century there was realization that faraway objects could appear much closer. Since that time the telescope has evolved into a sophisticated and high precision magnification instrument. From basic optical facts, man has also created microscopes, cameras and other important scientific equipment. Thus, the greater part of our present day knowledge of many of the natural processes in men, animals, and plants in addition to our overall comprehension of nearly everything in the vast universe in which we live has come from the invention of many types of optical instruments.

By far one of the best websites of all, with a great deal of information regarding the early telescope, is the Institute and Museum of the History of Science (IMSS). A link to their website can be found here: http://brunelleschi.imss.fi.it/esplora/cannocchiale. A great deal of information regarding the early telescope is presented in an interesting fashion. You can also learn more about Galileo’s two surviving instruments in Florence by reviewing the Catalogue of Early Telescopes written in 1999 by Albert Van Helden.


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