## The Practice of Navigation: And Nautical Astronomy |

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

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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 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 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 vii - This is the more important, as very indistinct and erroneous notions prevail among practical persons on the subject of accuracy of computation ; and much time is, in consequence, often lost in computing to a degree of precision wholly inconsistent with that of the elements themselves. The mere habit of working invariably to a useless precision, while it can never advance the computer's knowledge of the subject, has the unfavourable tendency of deceiving those who are not aware of the true nature...

Page 147 - 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 22 - A CIRCLE is a figure bounded by a curve line called the circumference,* of which every point is at the same distance from a point within, called the centre. Thus, ABD is a circle, and C the centre.

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 37 - ... the three interior angles of' a triangle are together equal to two right angles.

Page 39 - Hence it is plain that triangles on the same or equal bases, and between the same parallels, are equal, seeing (by cor.

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.