The American Practical Navigator: Being an Epitome of Navigation and Nautical AstronomyU.S. Government Printing Office, 1906 - 652 páginas |
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Términos y frases comunes
A. M. Hour apparent azimuth barometer bearing Beaufort scale body Center chart Chro chronometer Church circle Coast column compass Corr correction corresponding Cosecant Cosine Cotangent course dead reckoning declination deviation Diff Difference of Latitude difference of longitude direction Dist distance E.
H. W.
L. W. Spg earth east equator error Extreme flagstaff Greenwich Greenwich mean h. m.
h. m. ft Harbor horizon hour angle Hour P. M. Hour intersection Island Islet Latitude and Departure light Light-house logarithm longitude magnetic MARITIME POSITIONS mean measured meridian altitude method miles minutes moon's Nautical Nautical Almanac navigator Neap noon object observed P. M. Hour A. M. parallax parallel plane Port POSITIONS AND TIDAL refraction Right Ascension Rock sailing Secant sextant ship sidereal sight subtract Summit Sumner line sun's visible rising Table Tangent theodolite TIDAL DATA transit vertical vessel wind
Pasajes populares
Página 144 - He noticed objects above the earth tend to rotate relative to the earth's rotation ... to the right in the northern hemisphere, to the left in the southern. The Coriolis Effect is in force in outer space, too.
Página 181 - ... center. A small circle is a section" by a plane which intersects the sphere without passing through the center. A great circle may be drawn through any two points on the surface of a sphere, and the arc of that circle lying between those points is shorter than any other distance between them that can be measured npon the surface.
Página 114 - 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 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...
Página 288 - All the distances that can be observed on the same day, are grouped together under that date; and the columns are read from left to right, across both pages of the same opening. The letter W. or E. is affixed to the name of the sun, planet or star, to indicate that it is on the west, or east side of the moon.
Página 114 - 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 light, and at the ship, at the same instant of time; and it followed, that Small's light must bear ENE, if the Chronometer was right.
Página 68 - Having made the adjustments of the index and horizon mirrors and of the telescope, as previously described, it is necessary to find that point of the arc at which the zero of the vernier falls when the two mirrors are parallel, for all angles measured by the sextant are reckoned from that point. If this point is to the left of the zero of the limb, all readings will be too great ; if to the right of the zero, all readings will be too small. If...
Página 38 - Heretofore only those forces have been considered which -act when the vessel is on an even keel; but if there is an inclination from the vertical certain new forces arise, and others previously inoperative become effective. These forces are (a) the vertical component of the subpermanent magnetism acquired in building; (b) the vertical component of the induced magnetism in vertical soft iron, and (c) the magnetism induced by the vertical component of the earth's total force in iron which, on an even...
Página 45 - ... the fixed arm. To plot a position, the two angles observed between the three selected objects are set on the instrument, which is then moved over the chart until the three beveled edges pass respectively and simultaneously through the three objects. The center of the instrument will then mark the ship's position, which may be pricked on the chart or marked with a pencil point through the center hole. The...
Página 114 - ... 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 edge of the Bank. The weather was now more boisterous, and very thick; and the wind still Southerly; arriving about midnight, 17th December, within 40...
Página 88 - TRANSITS. 315. The most accurate method of finding the chronometer correction is by means of a transit instrument well adjusted in the meridian, noting the times of transit of a star or the limbs of the sun across the threads of the instrument. At the instant of the body's passage over the meridian wire, mark the time by the chronometer. The hour angle at the instant is Oh; therefore the local sidereal time, is equal to the right ascension of the body in the case of a star, or the local apparent...