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Longitude by chronometer
| Глоссарий морской лексики и терминологии (английский язык) |
Is estimated by the difference between the time at the place, and the time indicated by chronometer.
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Chronometer, английский
- A timekeeper accurate enough to be used to determine longitude by means of celestial navigation.
- A valuable time-piece fitted with a compensation-balance, adjusted for the accurate measurement of time in all climates, and used by navigators for the determination of the longitude.
- An especially accurate and highly consistent marine timepiece designed to facilitate course-plotting. before the fifteenth century, the only reliable means of navigation was to follow known features on the shore. then acquisition of the compass from china via arabia, and the astrolabe from islam allowed european mariners to calculate their approximate north-south position (latitude) while out of sight of land. however, in the absence of a reliable means of measuring time, their east-west location (longitude) could only be “guesstimated” through a complex process known as dead reckoning. the resultant errors caused numerous shipwrecks. in 1713, the british parliament offered the then immense reward of ?20,000 for any means of determining longitude with an error of less than thirty miles (48 kms) after six weeks at sea. this demanded precise timekeeping to within three seconds per day while pitching and tossing and traveling from frigid arctic to steaming equator; a degree of accuracy which had seldom been achieved by the finest stationary clocks in temperate zones. sixty years later, the prize was won by john harrison, a yorkshire carpenter and selftaught horologist. his first machines were costly, complicated, and delicate; but soon he and pierre le roy of paris (independently) developed more rugged marine timekeepers with all the essential features of a modern chronometer. by then, invention of the sextant had provided a more accurate means of calculating latitude. thus, by the great naval wars of late 18th and early 19th centuries, shipmasters could set out on long voyages with confidence in making an accurate landfall or rendezvous. today, after more than two centuries of use, chronometers are being replaced by electronic timekeepers.
- Хронометр
Chronometer rate, английский
The number of seconds or parts of seconds which it loses or gains per diem. (see rating.)
Chronometre, французский
Chronometreur, французский
Chronometric unit, английский
See geochronometric unit.
Chronometrophobia, английский
Longitude, английский
- The distance in degrees east or west of the meridian at greenwich, england.
- (географическая) долгота
- The distance in degrees east or west of the meridian at greenwich, england
- Долгота (географическая)
- Долгота
- Is an arc of the equator, or any parallel of latitude, contained between the meridian of a place and that of greenwich, or any other first meridian. these arcs being similar, are expressed by the same number of degrees and miles, though the absolute distance on the earth`s surface decreases as the latitude increases, for which see departure. east longitude extends 180 degrees to the right, when looking north, and west longitude as many to the left of the first meridian.
- The angular distance east or west of the standard meridian at greenwich (cf. latitude).
- Географическая долгота
- Imaginary lines drawn through the north and south poles on the globe used to measure distance east and west. greenwich, england, is designated as 0° with other distances being measured in degrees east and west of greenwich.
Longitude, английский
Longitude, английский
Longitude, английский
Longitude by account, английский
The distance east and west, as computed from the ship`s course and distance run, carried forward from the last astronomical determination.
Longitude by lunar observation, английский
The longitude calculated by observing the moon`s angular distance from the sun or a fixed star. it is the only check on chronometers, and very valuable in long voyages, though now much neglected, since the establishment of compulsory examination in the merchant service, which does not require lunars.
Longitude of a celestial body, английский
An arc of the ecliptic, contained between the first point of aries and a circle of longitude passing through the centre of the body.
Longitude, geocentric, английский
The angular distance of a heavenly body from the first
Longitude, heliocentric, английский
The angular distance of a body from the first point of aries, measured upon the ecliptic, as viewed from the sun.
Difference, английский
- Disagreement, inequity, contrast, dissimilarity, incompatibility
- Разница; разность
- An important army term, meaning firstly the sum to be paid by officers when exchanging from the half to full pay; and, secondly, the price or difference in value of the several commissions.
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Longitude by lunar observation, английский
The longitude calculated by observing the moon`s angular distance from the sun or a fixed star. it is the only check on chronometers, and very valuable in long voyages, though now much neglected, since the establishment of compulsory examination in the merchant service, which does not require lunars.
Longitude by account, английский
The distance east and west, as computed from the ship`s course and distance run, carried forward from the last astronomical determination.
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