the nautical almanac and astromical

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Page 525 - This inclination is ever varying, as well from the effect of its mean diminution, as of the nutation of the earth's axis: it is an important element in deducing the positions of...
Page 511 - Where time is deduced from observations of the Sun, the immediate result is apparent time ; to convert it into mean time, the equation of time is necessary, and it is to be applied to apparent time, according to the precept at the head of tue column.
Page 483 - The Moon's Libration is here supposed to take place in the plane of her orbit; and by the time of the greatest Libration of her apparent Disc is to be understood the instant at which, to an observer at the centre of the Earth, the variation of the Disc from its mean state has attained its maximum. The right-hand column indicates the quadrant of the Moon's Disc in which the Libration takes place, and in which the greatest change of the Moon's surface will become visible.
Page 511 - Day are the same in this Method as in the civil Account at Noon, and from Noon till Midnight; but from Midnight till Noon they differ; for whereas in the civil Account a...
Page 537 - Tables for determining the Latitude by Observations of the Pole Star out of the Meridian. The method of using them is as follows : From the observed altitude, when corrected for the error of the instrument, refraction, and dip of the horizon, subtract i'.
Page 518 - Lunar Distance has been observed on the surface of the Earth, and reduced to the centre, by clearing it of the effects of parallax and refraction, the numbers in these pages enable us to ascertain the exact Greenwich mean time at which the o' jects would have the same distance.
Page 513 - Sidereal Time at Mean Noon is the angular distance of the first point of Aries, or the true vernal equinox, from the meridian, at the instant of mean noon : it is therefore the Right Ascension of the mean Sun, or the time shown by a sidereal clock at Greenwich, when the mean time clock indicates oh om o*.

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