## The Practice of Navigation and Nautical Astronomy |

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### Common terms and phrases

add the log altitude alts angle appears azim azimuth bearing celestial body celestial equator centre chron chronometer circle coast compass Computation corr correction corresponding cosec course D.Lat Dist decl declination deviation difference direction distance divided equal equator error exceeds extr feet given gives greater Greenwich Date height of eye Hence horizon interval latitude less logarithms longitude lunar magnetic mean meridian miles moon moon's Nautical Almanac navigation nearly noon observation parallax Parallel Sailing Plane Sailing planet pole Port position prime vertical prop reckoned reduce refraction result rhumb line Right Ascension sailing Semid sextant shews ship ship's side sine square star subtract sum rejecting tens sun's TABLE TO DEGREES tide TRAVERSE TABLE triangle true true alt variation watch

### Popular passages

Page 32 - From the extremitiesof the base of anisosceles triangle straight lines are drawn perpendicular to the sides, the angles made by them with the base are each equal to half the vertical angle. 12. A line drawn bisecting the angle contained by the two equal sides of an isosceles triangle, bisects the third side at right angles. 13. If a straight line drawn bisecting the vertical angle of a triangle also bisect the base, the triangle is isosceles. 14. Given two points one on each side of a given straight...

Page 17 - The characteristic of a number less than 1 is found by subtracting from 9 the number of ciphers between the decimal point and the first significant digit, and writing — 10 after the result.

Page 39 - 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 400 - The glare of a powerful light is often seen far beyond the limit of visibility of the actual rays of the light, but this must not be confounded with the true range.

Page 163 - For the same body the semidiameter varies with the distance; thus, the difference of the sun's semidiameter at different times of the year is due to the change of the earth's distance from the sun; and similarly for the moon and the planets.

Page 127 - The distance between two points on the surface of a sphere is the length of the minor arc of a great circle between them.

Page 31 - And the remaining angles of the one coincide with the remaining angles of the other, and are therefore equal to them, namely, the angle ABC to the angle DEF, and the angle ACB to the angle DFE.

Page 400 - All the distances given in the Light Lists and on the charts for the visibility of lights are calculated for a height of an observer's eye of 15 feet.

Page 36 - A parallelogram is a four.sided figure, of which the opposite sides are parallel; and the diameter is the straight line joining two of its opposite angles.

Page 1 - When any part of the given sum .consists of mixed numbers or compound fractions, they must be first reduced to improper or single fractions. EXAMPLES. 1 . Reduce i, •J and -£ to equivalent fractions having a com?