An Introduction to the Practical and Theoretical Study of Nautical Surveying |
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An Introduction to the Practical and Theoretical Study of Nautical Surveying ... John Knox Laughton No preview available - 2009 |
Common terms and phrases
accuracy is required accurate altitude angular points approximation arithmetic mean artificial horizon axis base line chart chronometer circle coast compass corrections for curvature cosec course cross wires curvature and refraction difference of bearing difference of level difficulty draw drawn earth's surface equal error exact fixed gnomonic projection ground is soft height held upright horizontal angle hour angle instrument latitude latitude and longitude length longitude manner measured mercury meridian altitude meridian distance method miles minutes of arc nautical survey navigator necessary number of observations object observed angle once parallels of latitude plumb-line pole prime meridian radius reduction right angles scale second station sextant ship shore side sights sin² single observation sound spirit level staff backwards star staves is practically sufficient surveyor swaying the staff taken telescope theodolite triangle true bearing velocity of sound wooden picket flush zenith distance
Popular passages
Page 94 - The angle at the centre of a circle is double the angle at the circumference on the same arc.
Page 9 - The requisites are clean tinfoil and mercury (a hare's foot is handy) — lay the tinfoil, which should exceed the surface of the glass by a quarter of an inch on each side, on a smooth surface (the back of a book), rub it out smooth with the finger, add a bubble of mercury, about the size of a small shot, which rub gently over the tinfoil until it spreads itself and shows a silvered surface, gently add sufficient mercury to cover the leaf so that its surface is fluid. Prepare a slip of paper the...
Page 9 - Prepare a slip of clean paper the size of the tinfoil. Take the glass in the left hand, previously well cleaned, and the paper in the right. Brush the surface of the mercury gently to free it from dross. Lay the paper on the mercury, and the glass on it. Pressing gently on the glass, withdraw the paper. Turn the glass on its face, and leave it on an inclined plane to allow the mercury to flow off, which is accelerated by laying a strip of tinfoil as a conductor to its lower edge. The edges may, after...
Page vii - It is also a favourite dictum of Admiral Ryder's that a fair surveyor must be a good navigator. The battle of the Nile could never have been fought at the hour it -was if Nelson had not been a pilot as well as an Admiral. At Copenhagen, also, he made a rough survey of the approaches, and was thus able...
Page 39 - A convenient method, whenever available, is to determine the distance by noting the number of seconds elapsed between seeing the flash and hearing the report of a gun fired. The velocity of sound is 1 nautical mile in 5.6 seconds, or .18
Page 138 - London : Printed by ] Spottiswoode and Co., New-street Square \ and Parliament Street
Page 84 - In short, during the whole progress of a survey, it should be steadily borne in mind, that with whatever skill and labour it may be executed, it is only the means to an end ; and that its real merit will less depend on the science and taste which have been employed in its construction than on the practical utility of its results.
Page 82 - ... convey to the eye, not only the relative position of its principal points and inflexions, but its varying character — whether springing abruptly from the sea in precipitous cliffs, or rising in bold acclivities, or in gentle slopes — whether broken into scattered points of rock, or throwing...
Page 20 - ... or for the rediscovery of any old comet, or of any stars that have disappeared. Considering also the great importance (both in a nautical and...