Nicolas Bion. Simply put, Newton's theory, when combined with Hadley and Godfrey's invention lead to Bird's creation of the sextant. 35168 Burt applied the principles of his earlier solar compass invention to this new navigational instrument. In February of 1731 Stewart again set sail, this time for Saint John’s, Newfoundland. http://subaru2.univ-lemans.fr/enseignements/physique/02/optigeo/sextant.html (French) By looking through the main eyepiece of the sextant, you'll see a window with two sides - one of glass, and one mirrored. It would not be difficult to imagine a Royal Society that could not accept the idea that a colonial glass merchant might be given credit for the production of such an innovative and sophisticated device. http://www.afyacht.com/sestante.asp (Italian) 89081 The first affidavit, sworn by Edmund Wooley, carpenter, states that in or about November of 1730 he was employed by Thomas Godfrey to construct a special "sea-quadrant" to Godfrey’s specifications. Godfrey was employed for a time installing window glass at the Philadelphia State House (now Independence Hall). The Science museum, "Captain Cook's sextant, c 1772" 41561 - Musée des arts et métiers, Paris From the Sun's altitude at its passage on the meridian, the user could compute the latitude of the observation point by means of numerical tables. Dayne Rugh. He had a humble education. People have been sailing the world's oceans for thousands of years, and the invention of instruments such as the sextant made it easier for explorers to reach places across the globe. Why do you think the government was motivated to offer such large monetary prizes for these inventions. Museum of the History of Science, Oxford, inv. The sextant is also used in aerial navigation; in that case, the natural horizon line, often hard to distinguish, is replaced by an artificial horizon (the horizontal profile of a liquid). http://www.nautica.it/info/tecnica/sestante/ (Italian) Can you think of any professions that would benefit from their use? Florence, Museo Galileo. Department of History of Science, Harvard University, inv. In order for a sailor to determine how far north or south he was when out at sea, he needed to know his latitude. All that the Society would admit was that both inventions had occurred independently on both sides of the Atlantic. 1938-260 35300, Museum of the History of Science, Oxford, inv. 1932-584 XX, p. 206. Willem Janszoon Blaeu. 5252, Museum of Scientific Instruments, University of Toronto, inv. The instrument typically comes with several absorption filters to be inserted in the path of the Sun's rays. The first of these instruments to be invented can be credited to Englishman John Bird, a … http://www.vialattea.net/eratostene/contributi/nfesta/index.html (Italian) Sextants were first developed with wider arcs for calculating longitude from lunar observations, and they replaced octants by the second half of the 18th century. http://dailymotion.virgilio.it/video/xcd989_le-sextant_tech#from=embed (Video explaining how to make a sextant in French). 45880 Le grand atlas, ou, Cosmographie Blaviane, Amsterdam, 1667: il sesatnte astronomico di Tycho Brahe. Thomas Godfrey, born at Philadelphia in 1704, was gifted in intellect but poor in resources. The sextant (sixth part of a circle) is an instrument primarily used in navigation for measuring the altitude of the Sun or a celestial body above the horizon at sea. His new responsibilities took most of his time, and so it was not until 18 months later (May 1732) that Logan finally wrote to Dr. Edmund Halley (of Halley’s Comet fame) at the Royal Society, describing the essential parts of Godfrey’s device (see upper diagram at left). This is a very early example of his work now in the Nederlands Scheepvaart Museum in Amsterdam. The device that Thomas Hadley displayed to the Royal Society, and for which he received praise as inventor, bore a great deal of similarity to Godfrey’s design (see lower diagram on page 30). The Science museum, inv. Instead of pulling out a smartphone or a computer to determine location, sailors relied on the ancient art of celestial navigation, with the sextant eventually becoming one of their main navigational tools. II. Museum of the History of Science, Oxford, inv. Original content by: 35300 5315 Institute and Museum of the History of Science, inv. Museum of the History of Science, Oxford, inv. In October of 1730, the mariner, Stewart, brought Godfrey one of his quadrants to have it modified and reflecting glasses installed. 37495, - Department of History of Science, Harvard University From the Sun's altitude at its passage on the meridian, the user could compute the latitude of the observation point by means of numerical tables. 1931-95, - Museum of the History of Science, Oxford This page was last modified on 8 September 2010, at 10:08. The Science museum, inv. After positioning the sun on the mirror side, you turn the knob that moves the arm of the sextant, which will make the sun descend in the window. 36227 50963, Museum of the History of Science, Oxford, inv. Ruggero Giuseppe Boscovich. http://solarscience.msfc.nasa.gov/suntime/sxtnt_tchr.pdf (English) The altitude was shown on the graduated scale. Check out our sextant invention selection for the very best in unique or custom, handmade pieces from our shops.