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Секстанта
| Глоссарий технических терминов |
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Sextant, английский
- Секстант
- Navigational instrument used to measure a ship`s latitude.
- Секстан
- A mathematical instrument for taking altitudes of, and measuring the angular distances between, the heavenly bodies. it is constructed on a principle similar to hadley`s quadrant; but the arc contains a sixth part of a circle, and measures angles up to 120°.
- This navigational instrument, which measures the angle of elevation of a celestial object, was invented independently by american thomas godfrey and englishman john hadley in or about 1730. it rapidly replaced the astrolabe, being capable of taking sights at wider angles, and providing more precise measurements, by using a long beam of light rather than a short arm with inherent errors. moreover, even on a moving ship, the horizon and the celestial object seem to remain steady when viewed through opposing mirrors which compensate for movement. the user looks at the horizon through the clear lower half of a lens, while viewing the sky in the mirrored upper half. when an assistant calls out a timemark, the user adjusts the image of the celestial body (normally the sun), bringing it down until it just touches the horizon. the angle of elevation can then be read from a vernier scale with accuracy to the nearest ten seconds (1?360°) and can be translated into a position by any one of several mathematical procedures.
- A navigational instrument used to determine the vertical position of an object such as the sun, moon or stars, used for celestial navigation.
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Alizarine, английский
Schedllling, английский
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