A burning-glass is a large convex lens that can concentrate the sun's rays onto a small area, heating up the area and thus resulting in ignition of the exposed surface. A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging The Sun (Sol is the Star at the center of the Solar System. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of They were used in 18th-century chemical studies for burning materials in closed glass vessels where the products of combustion could be trapped for analysis. The 18th century lasted from 1701 to 1800 in the Gregorian calendar, in accordance with the Anno Domini / Common Era numbering system Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of The burning-glass was a useful contrivance in the days before electrical ignition was easily achieved. Burning mirrors achieve a similar effect by using reflecting surfaces to focus the light.

Contents 1 History 2 Current use 3 References 4 Further reading

History

The technology of the burning-glass has been known since antiquity. Vases filled with water used to start fires were known in the ancient world, and metaphorical significance was drawn (by the early Church Fathers, for instance) from the fact that the water remained cool even though the light passing through it would set materials on fire. The Church Fathers, Early Church Fathers, or Fathers of the Church are the early and influential theologians and writers in the Christian Church Burning lenses were used to cauterise wounds and to light sacred fires in temples. Cauterize redirects here For the band see Cauterize (band Cauterization is a medical term describing the burning of the body to remove Plutarch refers to a burning mirror made of joined triangular metal mirrors installed at the temple of the Vestal Virgins. Lucius Mestrius Plutarchus ( Greek: Μέστριος Πλούταρχος c In Ancient Rome, the Vestal Virgins ( sacerdos Vestalis) were the virgin Holy female Priests of Vesta, the Goddess of the Aristophanes mentions the burning-lens in his play The Clouds (424 BC). Aristophanes (Ἀριστοφάνης ˌærɪˈstɒfəniːz in English ca The Clouds (Νεφέλαι / Nephelai) is a comedy written by the Ancient Greek playwright Aristophanes lampooning the Sophists Events By place Persian empire Xerxes II rules as King of Persia for only about 45 days until he is killed

Archimedes, the renowned mathematician, was said to have used a burning glass (or more likely a large number of angled hexagonal mirrors) as a weapon in 212 BC, when Syracuse was besieged by Marcus Claudius Marcellus. Archimedes of Syracuse ( Greek:) ( c. 287 BC – c 212 BC was a Greek mathematician, Physicist, Engineer In Geometry and Trigonometry, an angle (in full plane angle) is the figure formed by two rays sharing a common Endpoint, called Regular hexagon The internal Angles of a regular hexagon (one where all sides and all angles are equal are all 120 ° and the hexagon has 720 degrees A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. Events By place Greece After being stopped twice by the Romans in his attempts to invade Illyria by sea and constrained by the Syracuse (Siracusa Sicilian: Sarausa, Classical Greek: / transliterated Syrakousai) is a historic City in Marcus Claudius Marcellus (ca 268 BC-208 BC was a Roman general one of the commanders of the Roman Army during the Second Punic War and the conqueror of Syracuse The Roman fleet was supposedly incinerated, though eventually the city was taken and Archimedes was slain. The Roman Navy ( Latin: Classis, lit "fleet" comprised the naval forces of the Roman state

The legend of Archimedes gave rise to a considerable amount of research on burning-glasses and lenses until the late 17th century. As a means of recording the passage of Time, the 17th Century was that Century which lasted from 1601 - 1700 in the Gregorian calendar Successful recreations have been performed by Anthemius of Tralles (C6 A. Anthemius of Tralles (c 474 &ndash c 534 ( Greek) was a Greek professor of Geometry in Constantinople (present-day Instanbul D. ), Proclus (C6 A. D. ) (who by this means purportedly destroyed the fleet of Vitellus besieging Constantinople), Roger Bacon (C13), Giambattista della Porta and his friends (C16), Athanasius Kircher and Gaspar Schott (C17), the Comte du Buffon in 1740 in Paris and Ioannis Sakas in the 1970s in Greece and others. Constantinople (Κωνσταντινούπολις Konstantinoúpolis, or gr ἡ Πόλις hē Polis, Latin: la CONSTANTINOPOLIS For the Nova Scotia premier see Roger Bacon (politician. Roger Bacon, O Athanasius Kircher (sometimes erroneously spelled Kirchner) was a 17th century German Jesuit Scholar who published around 40 works most Sakas was able to ignite a wooden boat at some distance in only seconds. Buffon, using only 48 small mirrors, was able to melt a 3 kilogram (six pound) tin bottle, and ignite wood from a distance of 46 meters (150 feet). These recreations show the plausibility of Archimedes' achievement.

The pop science TV program MythBusters attempted to model Archimedes' feat by using mirrors to ignite a small wooden boat covered with tar, with only partial success—they found it too difficult to focus light from their hand-held mirrors onto a point small enough to ignite the boat. MythBusters is a Popular science Television program produced by Australian firm Beyond Television Productions originally for the

Recent excavations at the Viking harbor town of Fröjel, Gotland in Sweden have revealed a small number of rock crystal lenses known as the Visby lenses. A Viking is one of the Norse ( Scandinavian Explorers Warriors Merchants, and pirates who raided and colonized wide areas is a county, province and municipality of Sweden and the largest Island in the Baltic Sea. "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. The Visby lenses are a collection of lens -shaped manufactured objects made of Rock crystal (quartz found in a Viking grave in Gotland dating These may have been made using pole-lathes. They have an imaging quality comparable to that of 1950s aspheric lenses. An aspheric lens or asphere is a lens whose surfaces have a profile that is neither a portion of a Sphere nor of a circular cylinder. The Viking lenses effectively concentrate sunlight enough to ignite fires; however it is not known whether they were used for this purpose. Similar technology may have been used in ancient Ireland (the Liath Meisicith) and quite possibly ancient Egypt.

In 1796, during the French Revolution and three years after the declaration of war between France and Great Britain, Étienne-Gaspard Robert met with the French government and proposed the use of mirrors to burn the invading ships of the British Royal Navy. The French Revolution (1789–1799 was a period of political and social upheaval in the History of France, during which the French governmental structure previously an Étienne-Gaspard Robert (1763–1837 often known by the stage name of " Robertson " was a prominent Belgian stage magician and influential The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore known as the Senior Service) They decided not to take up his proposal. ^[1]

Current use

Solar furnaces are used in industry to produce extremely high temperatures without the need for fuel or large supplies of electricity. For the cooking apparatus see Solar cooker. For electricity generation see Solar updraft tower. They employ a large parabolic array of mirrors (some facilities are several stories high) to focus light to a high intensity. In Mathematics, the parabola (pəˈræbələ from the Greek παραβολή) is a Conic section, the intersection of a right circular

References

Further reading

• Temple, Robert. The Crystal Sun, ISBN 0 7126 7888 3.

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