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anchor angle apparent altitude arch azimuth bearing cable calculation central altitude centre co-sec co-sine column compass corresponding course degrees Diff difference of latitude difference of longitude Dist Distſ elapsed equal equator error EXAMPLE feet Funchal given Greenwich half sum haul helm hour angle Latitude and Departure line of numbers logarithm mast mean meridian altitude method middle latitude miles minutes mizen moon moon's multiplied Nautical Almanac nearly noon º º object observed altitude ºil parallax parallel passing the meridian perpendicular plane Plane Sailing radius refraction right ascension rope rule sail sea account secant semi-diameter sextant ship ship's side sine star staysail subtracted sun's declination Suppose tack taken tangent tion topsail triangle true altitude true distance tude variation wind zenith distance
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 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 203 - 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.