A New and Accurate Method of Finding a Ship's Position at Sea, by Projection on Mercator's Chart ...: The Principles of the Method Being Fully Explained and Illustrated by Problems, Examples, and Plates, with Rules for Practice, and Examples from Actual Observation
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accurate assumed latitudes bearing body called centre chart circle correct corresponding curve dead reckoning declination determined diff difference of azimuth difference of longitude direction double altitudes earth's surface east or west elapsed equal altitude error of latitude error of longitude example extreme finding the apparent given gives greater Greenwich hour intersection known land latitude by dead less log rising longitude by chronometer manner mark mean azimuth meridian meridian observation method miles minutes moon motion namely Navigation noon noted observation parallel of equal parallel of latitude passes planets plate pole of illumination position practical problem projected proper reference respective resulting right angles rules sailed second observation ship shows side sphere straight line subtracted sun bears sun's taken tion true latitude tude turned usual watch
Page 47 - ... at about 10 AM an altitude of the sun was observed, and the Chronometer time noted ; but, having run so far without any observation, it was plain the Latitude by dead reckoning was liable to error, and could not be entirely relied on. Using, however, this Latitude, in finding the Longitude by Chronometer, it was found to put the ship 15
Page 22 - , crosses the second Sumner line will be the position of the ship at the time of the second observation, and a, her position at the first observation.
Page 50 - A small circle of a sphere is one whose plane does not pass through the centre of the sphere, and consequently divides the sphere into two unequal parts.
Page 47 - N. of the dead reckoning; this also placed the ship still further ENE, and still 27 nautical miles further; these three positions were then seen to lie in the direction of Small's light. It then at once appeared, that the observed altitude must have happened at all the three points and at Small's...
Page 47 - Greenock, a series of heavy gales from the westward promised a quick passage; after passing the Azores the wind prevailed from the southward, with thick weather; after passing longitude 21° W. no observation was had until near the land, but soundings were had not far, as was supposed, from the bank. The weather was now more boisterous and very thick, and the wind still southerly; arriving about midnight, 17th December, within 40 miles, by dead reckoning, of Tuskar light, the wind hauled SE.
Page 3 - Naval Library and Institute,' Navy Yard, Boston, April 30th, 1843. I certify the above to be a true Copy of the Report, (Copy.) (Signed) W. WHELAN, Recording Secretary. Navy Yard, Boston, 9th May, 1843.
Page 47 - ... close to the wind and several tacks made to preserve her position as nearly as possible until daylight, when, nothing being in sight, she was kept on ENE. under short sail with heavy gales. At about 10 am an altitude of the sun was observed and the chronometer time noted; but, having run so far without...
Page 47 - December, within 40 miles, by dead reckoning, of Tusker light, the wind hauled SE true, making the Irish coast a lee shore; the ship was then kept close to the wind, and several tacks made to preserve her position as nearly as possible until daylight, when, nothing being in sight, she was kept on ENE under short sail with heavy gales. At about...