American Practical Navigator: An Epitome of Navigation and Nautical Astronomy |
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Page 29
... possible identical . practice the two thermometers are gener- ally inclosed within a small lattice case , such as that shown in figure 6 ; the case should be placed in a position on deck remote from any source of artificial heat ...
... possible identical . practice the two thermometers are gener- ally inclosed within a small lattice case , such as that shown in figure 6 ; the case should be placed in a position on deck remote from any source of artificial heat ...
Page 43
... possible , through all the points . THE THEORY OF DEVIATION.a 96. FEATURES OF THE EARTH'S MAGNETISM . - It has already been stated that the earth acts like a great spherical magnet , with a pole in each hemisphere which is not ...
... possible , through all the points . THE THEORY OF DEVIATION.a 96. FEATURES OF THE EARTH'S MAGNETISM . - It has already been stated that the earth acts like a great spherical magnet , with a pole in each hemisphere which is not ...
Page 47
... possible , by solving equations , to determine what effect each force has in producing the semicircular deviation ; having done which , the subpermanent magnetism can be corrected by permanent magnets after the method previously ...
... possible , by solving equations , to determine what effect each force has in producing the semicircular deviation ; having done which , the subpermanent magnetism can be corrected by permanent magnets after the method previously ...
Page 50
... possible to those that exist when the compensation is completed ; therefore the quadrantal correctors should first be placed on their arms at the positions which it is estimated that they will occupy later when exactly located . An ...
... possible to those that exist when the compensation is completed ; therefore the quadrantal correctors should first be placed on their arms at the positions which it is estimated that they will occupy later when exactly located . An ...
Page 53
... possible with a vessel which is constantly rolling . 126. FLINDERS BAR . - The simplest method that presents itself for the placing of the Flinders bar is one which is available only for a vessel crossing the magnetic equator . Magnetic ...
... possible with a vessel which is constantly rolling . 126. FLINDERS BAR . - The simplest method that presents itself for the placing of the Flinders bar is one which is available only for a vessel crossing the magnetic equator . Magnetic ...
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Common terms and phrases
azimuth barometer bearing celestial sphere Center chart Chro chronometer Church circle Coast Corr correction corresponding cosec course dead reckoning declination departure determined deviation Diff Difference of Latitude difference of longitude direction Dist E.
H. W.
L. W. Spg earth east equal equator EXAMPLE Extreme Flagstaff Greenwich Greenwich mean h. m.
h. m. ft Harbor Head horizon hour angle instrument intersection Island Islet light Lighthouse logarithm Long longitude lunitidal interval magnetic MARITIME POSITIONS mean sun measured meridian altitude method miles nat hav Nautical navigator Neap noon object Observatory observed altitude parallax parallel plane Port POSITIONS AND TIDAL prime vertical rhumb line right ascension Rock Sailing sextant ship ship's sidereal sight station Summit Sumner line sun's telescope theodolite TIDAL DATA tides true vertical vessel watch wind zenith distance
Popular passages
Page 257 - Each degree is divided into 60 equal parts called minutes, and each minute into 60 equal parts called seconds.
Page 26 - St.-Cu.) at the center of the group, but the thickness of the layer varies. At times the masses spread themselves out and assume the appearance of small waves or thin slightly curved plates. At the margin they form into finer flakes (resembling Ci.-Cu.) They often spread themselves out in lines in one or two directions.
Page 5 - Lines are generally marked as follows: 2 fathoms from the lead, with 2 strips of leather, 3 fathoms from the lead, with 3 strips of leather, 5 fathoms from the lead, with a white rag, 7 fathoms from the lead, with a red rag, 10 fathoms from the lead, with leather having a hole in it, 13 fathoms from the lead, same as at 3 fathoms...
Page 54 - ... 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...
Page 142 - Having sailed from Charleston, SC, 25th November, 1837, bound for 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,...
Page 257 - THEOREM. Every section of a sphere, made by a plane, is a circle.
Page 86 - Moon, having a distance of 90° or more, are brought into contact just at the wire of the telescope which is nearest the plane of the sextant, fixing the index, and altering the position of the instrument to make the objects appear on the other wire ; if the contact still remains perfect, the axis of the telescope is in proper adjustment ; if not, it must be altered by moving the two screws which fasten, to the up-and-down piece, the collar into which the telescope screws. This adjustment is not...
Page 97 - Sun, and other fundamental astronomical data for equi-distant intervals of Greenwich mean time. Part II, Ephemeris for the Meridian of Washington, gives the ephemerides of the fixed stars, sun, moon, and major planets for transit over the meridian of the old Naval Observatory, Washington.
Page 95 - Time, which is perfectly equable in its increase, is measured by the motion of this mean sun. The clocks in ordinary use and the chronometers used by navigators are regulated to mean solar time. True, or Apparent Solar Time is measured by the motion of the real sun. The difference between apparent and mean time is called the Equation of Time.