Gregorian optics are also used in radio telescopes such as Arecibo, which features a "Gregorian dome". The Gregorian telescope design is rarely used today, as other types of reflecting telescopes are known to be more efficient for standard applications. ![]() The telescope design attracted the attention of several people in the scientific establishment such as Robert Hooke, the Oxford physicist who eventually built the telescope 10 years later, and Sir Robert Moray, polymath and founding member of the Royal Society. According to his own confession, Gregory had no practical skill and he could find no optician capable of actually constructing one. In his design he also placed a concave secondary mirror with an elliptical surface past the focal point of the parabolic primary mirror, reflecting the image back through a hole in the primary mirror where it could be conveniently viewed. Gregory pointed out that a reflecting telescope with a parabolic mirror would correct spherical aberration as well as the chromatic aberration seen in refracting telescopes. In his 1663 Optica Promota, James Gregory described his reflecting telescope which has come to be known by his name, the Gregorian telescope. The book was reprinted in 1668 with an appendix, Geometriae Pars, in which Gregory explained how the volumes of solids of revolution could be determined. "The first proof of the fundamental theorem of calculus and the discovery of the Taylor series can both be attributed to him." Following the example of Huygens, he also gave constructions of straight lines equal to the arcs of the circle, and whose error is still less. By means of these theorems he gives with infinitely less trouble than by the usual calculations, … the measure of the circle and hyperbola (and consequently the construction of logarithms) to more than twenty decimal places. Vera Circuli et Hyperbolae Quadraturaīefore he left Padua, Gregory published Vera Circuli et Hyperbolae Quadratura (1667) in which he approximated the areas of the circle and hyperbola with convergent series: cannot be denied the authorship of many curious theorems on the relation of the circle to inscribed and circumscribed polygons, and their relation to each other. He also described the method for using the transit of Venus to measure the distance of the Earth from the Sun, which was later advocated by Edmund Halley and adopted as the basis of the first effective measurement of the Astronomical Unit. In the Optica Promota, published in 1663, Gregory described his design for a reflecting telescope, the " Gregorian telescope". Vera circuli et hyperbolae quadratura, 1667 Optica Promota He died a few days later at the age of 36. He was the grandfather of John Gregory (FRS 1756) uncle of David Gregorie (FRS 1692) and brother of David Gregory (1627–1720), a physician and inventor.Ībout a year after assuming the Chair of Mathematics at Edinburgh, James Gregory suffered a stroke while viewing the moons of Jupiter with his students. He had married Mary, daughter of George Jameson, painter, and widow of John Burnet of Elrick, Aberdeen their son James was Professor of Physics at King's College, Aberdeen. He was successively professor at the University of St Andrews and the University of Edinburgh. There at the University of St Andrews, he laid the first meridian line across the floor of his lab in 1673, which was 200 years prior to the Greenwich Meridian being established, and thus "arguably making St Andrews the place where time began". Upon his return to London in 1668 he was elected a Fellow of the Royal Society, before travelling to St Andrews in late 1668 to take up his post as the first Regius Professor of Mathematics at the University of St Andrews, a position created for him by Charles II, probably upon the request of Robert Moray. At Padua he lived in the house of his countryman James Caddenhead, the professor of philosophy, and he was taught by Stefano Angeli. In 1664 he departed for the University of Padua, in the Venetian Republic, passing through Flanders, Paris and Rome on his way. ![]() In 1663 he went to London, meeting John Collins and fellow Scot Robert Moray, one of the founders of the Royal Society. He attended Aberdeen Grammar School, and then Marischal College from 1653–1657, graduating AM in 1657. ![]() After his father's death in 1651 his elder brother David took over responsibility for his education. It was his mother who endowed Gregory with his appetite for geometry, her uncle – Alexander Anderson (1582–1619) – having been a pupil and editor of French mathematician Viète. His mother Janet was the daughter of Jean and David Anderson and his father was John Gregory, an Episcopalian Church of Scotland minister, James was youngest of their three children and he was born in the manse at Drumoak, Aberdeenshire, and was initially educated at home by his mother, Janet Anderson (~1600–1668).
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