The Practical Navigator, and Seaman's New Daily Assistant: Being an Epitome of Navigation: Including the Different Methods of Working the Lunar Observations. With Every Particular Requisite for Keeping a Complete Journal at Sea ... To this Edition are Added ... the Requisite Tables Used with the Nautical Almanac in Determining the Longitude at Sea ...

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sold, 1791 - Nautical astronomy - 296 pages
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Page 21 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees ; and each degree into 60 equal parts, called minutes ; and each minute into 60 equal parts, called seconds ; and these into thirds, etc.
Page 16 - EXAMPLE. If the diameter of a circle be 7 inches, and the circumference 22, what is the circumference of another circle, the diameter of which is 14 inches ? Extend from 7 to 22, that extent will reach from 14 to 44 the same way.
Page 34 - ... the sum of the segments of the base is to the sum of the sides as the difference of the sides to the difference of the segments of the base.
Page 15 - All fractions found in this line must be decimals ; and if they are not, they must be reduced into decimals, which is easily done by extending the compasses from the denominator to the numerator; that extent laid the same way, from 1 in the middle or right hand, will reach to the decimal required.
Page 265 - A figurative expression for the timbers. /fuie at anchor, is when a ship is held by her anchors, and is not driven by wind or tide. To ride athwart, is to ride with the ship's side to the tide. To ride hoirie fallen, is •when the water breaks into the hawse in a rough sea.
Page 155 - Complement of the Latitude Is to Radius, So is the Sine of the Sun or Star's Declination To the Sine of the true Amplitude ; Which is always of the fame Name with the Declination, whether North or South.
Page 124 - The most usual way of discovering the set and drift of an unknown current, is thus : Let three or four men take a boat a little way from the ship : and by a rope fastened to the boat's stern, let down a heavy iron pot or loaded kettle to the depth of 80 or 100 fathoms ; then heave the log, and the number of knots run out in half a minute will be the miles the current sets per hour, and the bearing of the log will show the set of it.
Page 16 - The solid content of any bale, box, chest, fcc. is found by extending from 1 to the breadth ; that extent will reach from the depth to a fourth number, and the extent from 1 to that fourth number will reach from the length to the solid content.
Page 209 - PM per watch, the altitude of the sun's lower limb was 28 20' above the horizon of the sea, the eye being elevated 20 feet above the surface of the water, and the sun's bearing by compass S. by W. and at 2h. 58m. 2Gs. PM by watch, the altitude of the sun's lower limb was 16 41...
Page 168 - A ship lying-to under her mainsail, with her starboard tacks aboard, comes up E. by S. and falls off NE by E. there being one point westerly variation, and she makes 5 points lee-way — what course does she make good ? The middle between E. by S. and NE by E. is E. by N. ; and by allowing 6 points to the left hand (viz.

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