## The practice of navigation and nautical astronomy. [With] Tables [and] Supplement to the first ed, Volume 26 |

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The Practice Of Navigation And Nautical Astronomy. [with] Tables [and ... Henry Raper No preview available - 2019 |

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### Common terms and phrases

altitude alts angle appears apply azimuth bearing body called centre circle Coast compass Computation corr correction corresponding course D.Lat Dist Date decl declination determined diff difference direction distance divided East effect employed entr equal equator error extr feet figure given gives greater half Harb head height Hence horizon hour-angle increased interval latitude less longitude mean measured meridian method miles minutes moon moon's nearly noon North object observation obtained parallel passes Port position reduce result sailing seconds ship side sine South star subtract sun's Table taken term TRAVERSE TABLE true variation watch West

### Popular passages

Page 41 - 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 147 - Since the apparent altitude is too great on account of refraction, and too small on account of parallax, the diff. between these quantities is the diff. between the true and apparent altitudes. This difference, or the combined effect of parallax and refraction, is called the Correction of Altitude. The moon's Corr. of Alt. is given in Table 39; that of a star is merely its refraction. 439. The SEMI-DIAMETER of a celestial body is half the angle subtended by the diameter of the visible disc. Thus...

Page 38 - 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 19 - 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 43 - ... section shall be parallel to the remaining side of the triangle. Let DE be drawn parallel to BC, one of the sides of the triangle ABC: then BD shall be to DA, as CE to EA. Join BE, CD; then the triangle BDE is equal...

Page 105 - 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 186 - A line drawn from Polaris perpendicular to the line of the Pointers, and on the opposite side to the Great Bear, passes, at 48° distance, through CAPELLA, one of the brightest stars. In this same line, about the same distance on the opposite side of the pole, is a.

Page 145 - ... of Altitude are circles parallel to the horizon. 431. ZENITH DISTANCE is the arc included between the zenith and the celestial body, or the angular distance of a body from the zenith of which that arc is the measure. The zenith distance is, therefore, the complement of the altitude to 90°, as Z A.

Page 4 - RULE. Multiply all the numerators together for a new numerator, and all the denominators for a new denominator: then reduce the new fraction to its lowest terms.

Page 358 - Frigate La Venus, 1836-9, vol. iii. p. 419) paid particular attention to this indication, and remarks that the observations generally shew a lowering of the thermometer on approaching land, but they disprove that the water on a bank is always colder.* 1039. The temperature of the sea has been observed to change several degrees, in intervals of time varying from a few hours to a day and a half previous to a change of wind, the water becoming gradually warmer when the wind was about to blow from a...