. 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. . igure on the right, we find the True Azimuth is to the Right of the Magneti*Azimuth. IfO NAbllLAl. ASTRONOMY. EFFECT OF LOCAL ATTRACTION ON THE SHIPS COMPASS. This is a very important matter for investigation, and should be attended to at the earliest possilDle oppor-^tunity, because, in consequence of not knowing that Local Attraction existed on board, many vesseli havebeen -wrecked from that very cause. There being large quantities of Iron
. 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. . igure on the right, we find the True Azimuth is to the Right of the Magneti*Azimuth. IfO NAbllLAl. ASTRONOMY. EFFECT OF LOCAL ATTRACTION ON THE SHIPS COMPASS. This is a very important matter for investigation, and should be attended to at the earliest possilDle oppor-^tunity, because, in consequence of not knowing that Local Attraction existed on board, many vesseli havebeen -wrecked from that very cause. There being large quantities of Iron now used in the construction of Ships, besides the quantities whichithey carry to and fro, and stowed in different parts of the vessel as cargo, renders every Ship liable tonave her Compasses deranged by Local Attraction. And the general effect which Iron, s^ituated in th»» lor-ward part of a vessel, has on the Compass, is to draw the North end of the Needle forward in North Lat»4tude, and the South end of the Needle forward in South Latitude, and which the following Diagram will<^ow- DIAGRAM, %,owing the Effect of Local Attraction. Fig. fflten the Attracting Force is Forward. In the above figure, the dotted line will show the course intended to be steered, which in the one ca*e u4!ast. But the North end of the Needle being drawn forward from the effect of the Local Attraction,.{Caused by the Iron forward acting on it), the Ship is actually going E. by S. ; and in the other case,•«teering West, the North end of the Needle being drawn forward in like manner, the Ship is actually goingW. by S. Now suppose the Ship to steer North, the North end of the Needle will point in the direction of the dis-turbing force, and which being then on the same line as the Magnetic Meridian, no Local Attraction will•be perceptible. Hence, when tlie Ships head is at North or South, little or no deviation will be found in the Compass : butwhen her head is at East or West, or nearly s
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectnavigat, bookyear1902
