. A new treatise on the practice of navigation at sea : containing all the details necessary to enable the mariner to become a good practical navigator. . •V V o Nr^ RATIONAL HORIZON E.^W. POINTS TO CONSTUCT THE the Chord of 60 describe a semi-circle, and draw the Horizontal and Prime Vertical lines at RightAngles to each other. Elevate the Polar Axis equal to the Latitude of 45* N., and draw the Equator atRight Angles to it. Lay off the Stars Declination, 16° 13, on the Meridian to the North of the Equator,which will be the place of the Star, and its Distance measured from the Hor
. A new treatise on the practice of navigation at sea : containing all the details necessary to enable the mariner to become a good practical navigator. . •V V o Nr^ RATIONAL HORIZON E.^W. POINTS TO CONSTUCT THE the Chord of 60 describe a semi-circle, and draw the Horizontal and Prime Vertical lines at RightAngles to each other. Elevate the Polar Axis equal to the Latitude of 45* N., and draw the Equator atRight Angles to it. Lay off the Stars Declination, 16° 13, on the Meridian to the North of the Equator,which will be the place of the Star, and its Distance measured from the Horizon, is the Altitude , as the Elevation of the upper end of the Equator above the Horizon, is equal to the Co-Latitude ofthe place, which is North, and the Declination of the Star being also North, their Sum is the MeridiaaItitude of the Star, 61* 13, South of the observer, because his Latitude is North. Find th« Mxridiam Altitude er the Star Antarei in the Latitodk or 30* North. Fig. on the Plane of the Prime VertieaL. TO CONSTRUCT THE FIGURE. With the Chord of 60*, describe a semi-circle as before, which will represent the Prime Vertioal CireleDraw the Rational Horizon line, and at right angles to it from the centre, draw the Meridan line or Spectator is now facing the South. The Prime Vertical Circle passes through the East point of th«Horizon on the Left, and through the West point of the Horizon on the Right. The Elevation of the Celestial Equator above the Horizon being equal to the Co-Latitude, take bO* theCo-Latitude) from the lino of semi-tangents, and lay it off on ihe Meridian line. Then through thiapoint, and the East and West points of the Horizon, draw the Celestial Equator. From the line of semi-tangents take the Stars Declination, 26* 6 South, (measured from 60* backwards,) and lay it off from th«Equator towards the South point of the Horizon on the Meridian line, and draw the Parallel of Declinationparallel to the Equator.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectnavigat, bookyear1902
