The New American Practical Navigator: Being an Epitome of Navigation; Containing All the Tables Necessary to be Used with the Nautical Almanac, in Determining the Latitude, and the Longitude by Lunar Observations ... : With an Appendix Containing Methods of Calculating Eclipses of the Sun and Moon ...Edmund M. Blunt, Proprietor and author of the American coast pilot ; John Gray & Company, Print., 1826 - Nautical astronomy - 617 pages |
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Page viii
... central mirror , those surfaces being supposed to be perpendicular to the plane of the instrument . The correction in the fifth column of this table corresponding to any angle A in the first column may be found nearly by viii PREFACE .
... central mirror , those surfaces being supposed to be perpendicular to the plane of the instrument . The correction in the fifth column of this table corresponding to any angle A in the first column may be found nearly by viii PREFACE .
Page 94
... sun's apper ctions to be applied to obtain the true central altitude , will be given hereafter . the escopes , the one representing the objects erect or in ( 94 ) Description and use of a sextant of reflection To adjust a sextant.
... sun's apper ctions to be applied to obtain the true central altitude , will be given hereafter . the escopes , the one representing the objects erect or in ( 94 ) Description and use of a sextant of reflection To adjust a sextant.
Page 98
... central mirror . If the first distance exceeds the second , the error is subtractive , otherwise additive , the mirror being in its first position ; but the contrary when in its second position . Thus , if the first distance was 119 ...
... central mirror . If the first distance exceeds the second , the error is subtractive , otherwise additive , the mirror being in its first position ; but the contrary when in its second position . Thus , if the first distance was 119 ...
Page 97
... central mirror and turning it , so that the edge which was formerly uppermost may now be rearest the plane of the instrument ; rectify its position and again measure the distance of the two objects ; half the difference between these ...
... central mirror and turning it , so that the edge which was formerly uppermost may now be rearest the plane of the instrument ; rectify its position and again measure the distance of the two objects ; half the difference between these ...
Page 98
... central mirror . If the first distance exceeds the second , the error is subtractive , otherwise additive , the mirror being in its first position ; but the contrary when in its second position . Thus , if the first distance was 119 ...
... central mirror . If the first distance exceeds the second , the error is subtractive , otherwise additive , the mirror being in its first position ; but the contrary when in its second position . Thus , if the first distance was 119 ...
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Common terms and phrases
anchor angular distance apparent altitude arch azimuth bearing calculation central index centre chronometer circle co-sec co-sine column compass corresponding course sailed degrees diameter Diff difference of latitude difference of longitude Dist divided draw elapsed equal equator error EXAMPLE feet Funchal given gives Greenwich half sum horizon glass hour angle hypotenuse instrument latitude and departure line of numbers logarithm mean meridian altitude method middle latitude miles minutes moon moon's multiplied Nautical Almanac nearly noon object observed altitude obtained parallax parallel passing the meridian perpendicular Plane Sailing points poles quadrant radius 90 refraction right ascension rule sea account secant semi-diameter sextant ship ship's side sine square star subtracted sun's declination sun's lower limb Suppose taken tangent telescope tion TRAVERSE TABLE triangle true altitude true distance tude variation watch wind zenith distance
Popular passages
Page 10 - 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 5 - In a right triangle, the side opposite the right angle is called the hypotenuse, and the other two sides the legs.
Page 187 - If the vessel be double-decked, take the length thereof from the fore part of the main stem, to the after part of the stern post, above the upper deck"; the breadth thereof at the broadest part above the main wales...
Page 28 - To find the logarithm of a vulgar fraction. RULE. Subtract the logarithm of the denominator from the logarithm of the numerator...
Page 240 - Sear up, or bear away, is to change the course of a ship, in order to make her run before the wind...
Page 13 - TO THEIR DIFFERENCE ; So IS THE TANGENT OF HALF THE SUM OF THE OPPOSITE ANGLES', To THE TANGENT OF HALF THEIR DIFFERENCE.
Page 205 - The cause of the tides is the unequal attraction of the sun and moon upon different parts of the earth. For they attract the parts of the earth's surface nearest to them, with a greater force than they do its centre : and attract the centre more than they do the opposite surface. To restore this equilibrium the waters take a spheroidal figure, whose longer axis is directed towards the attracting luminary.
Page 187 - ... take the depth from the under side of the deck plank to the ceiling in the hold, then multiply and divide as aforesaid, and the quotient shall be deemed the tonnage.
Page 6 - CO-SINE of an arch is the sine of the complement of that arch, or of what that arch wants of a quadrant ; thus AH being a quadrant, the arch SH is the complement of the arch AS ; SZ is the sine of the arch SH, or the co-sine of the arch AS. XXI. The VERSED SINE of an arch is that part of the diameter...
Page 91 - The index and horizon glasses must be perpendicular to the plane of the instrument, and their planes parallel to each other, when the index division of the vernier is at 0° on the arc ; and the optical axis of the telescope must be parallel to the plane of the instrument. We shall speak separately of each of these adjustments.