Navigation and Nautical Astronomy

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D. Van Nostrand Company, 1898 - Nautical astronomy - 221 pages

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Page 98 - A cos 6 = cos a cos c + sin a sin c cos B cos c = cos a cos 6 + sin a sin 6 cos C Law of Cosines for Angles cos A = — cos B...
Page 50 - ... mean sun" which moves in a uniform rate along the equator. This is called mean solar time. The difference between mean and apparent time is called the equation of time. To convert apparent time into mean time, take from the Nautical Almanac the equation of time and add it or subtract it according to the direction given at the column.
Page 72 - Almanac the two distances between which the true distance falls; take out the nearer of these, the hours of Greenwich time over it, and the PL of Diff. between them. Find the difference between the true distance and the distance taken Jrom the Almanac; and from the proportional logarithm of this difference, as found in the Navigator, subtract the PL of Diff.
Page 100 - ... or if the bearing at this time is interpolated for from previous and subsequent bearings per compass, the error of the compass can be found. It has already been shown that compass error is the difference between the true and compass bearings of a heavenly body at the same instant, and is marked E. when the true bearing is to the right of the compass bearing, W. when the true bearing is to the left of the compass bearing.
Page 50 - ... uniform, and this for two reasons: 1st. The sun does not move in the equator, but in the ecliptic, so that, even were the sun's motion in the ecliptic uniform, its equal changes of longitude would not produce equal changes of right ascension; 2d. The sun's motion in the ecliptic is not uniform. To obtain a uniform measure of time depending on the sun's motion, the following method is adopted. A fictitious sun, which we shall call the...

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