. A treatise on surveying and navigation: uniting the theoretical, the practical, and the educational features of these subjects. AB ? ( See last figure.) Ans. lat. 70° 31 44. 8. Take the 2d example in plane sailing ( page 181 ), the depar-ture made, as stated in the answer, is miles. What is thecorresponding difference of longitude ? Ans. 5° 18 24. This inquiry now arises. To what latitude does this departurecorrespond? Is it to the latitude left, 41° 9, or to the latitude ar-rived at, 44° 41 ? Or does it correspond to the mean latitude be-tween the two ? If we suppose the departure cor
. A treatise on surveying and navigation: uniting the theoretical, the practical, and the educational features of these subjects. AB ? ( See last figure.) Ans. lat. 70° 31 44. 8. Take the 2d example in plane sailing ( page 181 ), the depar-ture made, as stated in the answer, is miles. What is thecorresponding difference of longitude ? Ans. 5° 18 24. This inquiry now arises. To what latitude does this departurecorrespond? Is it to the latitude left, 41° 9, or to the latitude ar-rived at, 44° 41 ? Or does it correspond to the mean latitude be-tween the two ? If we suppose the departure corresponds to lat. 41° 9, then thedifference of longitude by the preceding rule must be 5° 10, and ifthe departure corresponds to lat. 44° 41, then the difference of lon-gitude is 5° 28; the mean of these is 5° 19, and if we take the de-parture to correspond with the mean latitude 42° 55, then the dif-ference of longitude would be 5° 18 24. In the examples under Plane Sailing we have supposed the eartha plane, and the course a ship sails a straight line, but neither sup-position is strictly true. PLANE SAILING. 185. Meridians are not parallel with each other, and therefore when aship sails by the compass, and cuts all the meridians at the sameangle, the line that the ship sails will not be a right line : it will bea curve line peculiar to itself, called a rhumb line. For the sake of illustration, let us supposethat in the annexed figure, P is the northpole, KQ the equator, or a great circle,every part of which is a quadrant distancefrom P ; PK, PL, PM, &c, great circlespassing through P, and of course cuttingthe equator at right angles; AT, bB, PS,&c, arcs of smaller circles parallel to theequator, and therefore cutting the meridiansat right angles ; AE a curve cutting everymeridian which it meets, as PK, PL, PM, &c, at the same PK, PL, &c, produced till they meet at the opposite pole,are called meridians ; AT, bB, PS, &c, continued round the globe,are calle
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Keywords: ., boo, bookcentury1800, booksubjectnavigation, booksubjectsurveying
