# American Practical Navigator (Google eBook)

U.S. Government Printing Office, 1821 - Nautical astronomy

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I think this book is wonderful with rich talents of a boy and the way he looks at things.

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Page 10 - In any triangle, the sum of the three angles is equal to two right angles, or 180°.
Page 120 - ... or taking their difference when of contrary names ; the altitude to be reckoned from the south point of the horizon, when the latitude is north, and the contrary when south ; but when the sum exceeds 90°, it is to be taken from 180°...
Page 186 - To find the solidity of a pyramid and of a cone. RULE. — Multiply the area of the base by one third of its altitude, and the product will be its solidity.
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 32 - To find the logarithm of a vulgar fraction. RULE. Subtract the logarithm of the denominator from the logarithm of the numerator...
Page 208 - ... the miles the current sets per hour, and the bearing of the log will show the set of it. There is a very remarkable current, called the GULF STREAM, which sets in a north-east direction along the coast of America, * From Nathaniel Bowditch, THE NEW AMERICAN PRACTICAL NAVIGATOR, E.
Page 17 - TO THEIR DIFFERENCE ; So IS THE TANGENT OF HALF THE SUM OF THE OPPOSITE ANGLES', To THE TANGENT OF HALF THEIR DIFFERENCE.
Page 594 - In spherical triangles, whether right angled or oblique angled, the sines of the sides are proportional to the sines of the angles opposite to them.
Page 186 - 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...