American Practical Navigator

Front Cover
U.S. Government Printing Office, 1880 - Nautical astronomy
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Page 11 - The angle in a semicircle is a right angle ; the angle in a segment greater than a semicircle is less than a right angle ; and the angle in a segment less than a semicircle is greater than a right angle.
Page 15 - In any plane triangle, as the sum of the sides about the vertical angle is to their difference, so is the tangent of half the sum of the angles at the base to the tangent of half their difference.
Page 15 - In any plane triangle, the sum of any two sides is to their difference as the tangent of half the sum of the opposite angles is to the tangent of half their difference. By Theorem II. we have a : b : : sin. A : sin. B.
Page 6 - A plane rectilineal angle is the inclination of two straight lines to one another, which meet together, but are not in the same straight line.
Page 252 - Emersion (Em.) the instant of its reappearance at coming out of the shadow. They generally happen when the Satellite is apparently at some distance from the body of Jupiter, except near the opposition of Jupiter to the Sun, when the eclipse takes place near to the body of the planet.
Page 7 - In a right triangle, the side opposite the right angle is called the hypotenuse, and the other two sides the legs.
Page 231 - ... distance, to obtain the approximate Greenwich mean time corresponding to the given distance. If the distance between the Moon and a Star increased or decreased uniformly, the Greenwich...
Page 124 - ... to the depth of 80 or 100 fathoms ; then heave the log, and the number of knots run out in half a minute will be the miles the current sets per hour, and the bearing of the log will show the set of it. There is a very remarkable current, called the GULF STREAM, which sets in a north-east direction along the coast of America, from Cape Florida towards the Isle of Sables...
Page 146 - ... placed by the maker equidistant from each other and parallel to the middle one — therefore, when the middle one is adjusted, the others are so too ; he also places the two transverse wires at right angles to the vertical middle wire. These adjustments are always performed by the maker, and but little liable to derangement. When, however, they happen to get out of order, and the observer wishes to correct them, it is done by loosening the screws which hold the eye-end of the telescope in its...
Page 135 - ... to make the objects appear on the other wire ; if the contact still remains perfect, the axis of the telescope is in proper adjustment ; if not, it must be altered by moving the two screws which fasten, to the up-and-down piece, the collar into which the telescope screws. This adjustment is not very liable to be deranged.

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