The scales of the octant, sextant, quintant and quadrant are graduated from below zero to 90°, 120°, 140° and 180° respectively. For example, the sextant illustrated has a scale graduated from −10° to 142°, which is basically a quintant: the frame is a sector of a circle subtending an angle of 76° at the pivot of the … See more A sextant is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. The primary use of a sextant is to measure the angle between an astronomical object and the See more Like the Davis quadrant, the sextant allows celestial objects to be measured relative to the horizon, rather than relative to the instrument. This … See more A sight (or measure) of the angle between the sun, a star, or a planet, and the horizon is done with the 'star telescope' fitted to the sextant using a visible horizon. On a vessel at sea even on See more • Astrolabe • Bris sextant • Davis quadrant • Gago Coutinho • Harold Gatty • History of longitude See more The frame of a sextant is in the shape of a sector which is approximately 1⁄6 of a circle (60°), hence its name (sextāns, sextantis is the Latin word for "one sixth"). Both smaller and … See more Due to the sensitivity of the instrument it is easy to knock the mirrors out of adjustment. For this reason a sextant should be checked frequently for errors and adjusted accordingly. There are four errors that can be adjusted by the navigator, … See more • Her Majesty's Nautical Almanac Office Archived 2011-02-21 at the Wayback Machine • The History of HM Nautical Almanac Office Archived 2016-06-24 at the Wayback Machine • Chapter 17 from the online edition of Nathaniel Bowditch's American Practical … See more WebOct 20, 2024 · The arc. If the sextant is of the metal variety, the arc will be constructed of a thin strip of metal which has a low co-efficient of expansion. It is “let in” flush with the “lower limb” of the sextant and is graduated …

apparent edges of the discs of the sun or the moon; graduated …

Sep 21, 2024 · WebThe sextant is 2 ¾ inch in diameter with a 1 ¾ inch radius arc. The silvered scale is graduated every 30 minutes from –5° to 160° and may be read to one minute of arc by vernier.This example also has a supplementary angle scale, 90°–220°, as described in the description by Simms referenced above. dickinson 3 streaming sub ita

NMAH Navigation Sextant - National Museum of …

WebMar 29, 2024 · The sextant is an instrument used to measure angles. Its arc is one sixth of a circle. Hence it is called a sextant. In actual practice, the arc of the sextant is about … WebOct 20, 2024 · Every sextant is equipped with error adjustment screws. The design of these screws varies from sextant to sextant. Some have ordinary screw driver slots while others have round heads with a hole drilled … WebGraduated arc: graduated edge of the arc. Locking device: apparatus that holds the sextant in place. Drum: graduated button used to take measurements. Index arm: … dickinson 3 north prince of wales hospital