Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . 180° 120 110 100 80° 80° 70° 60° 50° 40° 80° Fig. 124.—EouiniSTANT Flat Pro-jection. Ttf70 60 50 10 sb 80 10 BO [ 0 I 0 3 0 s u 0 9 Fig. 125.—Mercators CylinderProjection. If wc imagine the equator as the middle parallel, quite abroad zone of the globe north and south of the equator may-be considered as coinciding with the surface of the this cylinder the meridians are represented as straight lines, 412 MAP COASTJ^UCT/ON. and the equator and pa
Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . 180° 120 110 100 80° 80° 70° 60° 50° 40° 80° Fig. 124.—EouiniSTANT Flat Pro-jection. Ttf70 60 50 10 sb 80 10 BO [ 0 I 0 3 0 s u 0 9 Fig. 125.—Mercators CylinderProjection. If wc imagine the equator as the middle parallel, quite abroad zone of the globe north and south of the equator may-be considered as coinciding with the surface of the this cylinder the meridians are represented as straight lines, 412 MAP COASTJ^UCT/ON. and the equator and parallels as circles of equal length cuttingthe parallels at right angles (Fig. 123, a). To represent a zoneat a higher latitude, we imagine, instead of the tangent cylinder,an intersecting one, also cutting the earths surface in the middleof the area to be represented. (Fig. 123, h.) If thereupon. Fig. 126.—Van der Grintens Circular Projection. we cut the cylinder along a meridian, we obtain two systemsof straight lines intersecting at right angles, representing theparallels and meridians. Maps on such projections are ingeneral called flat maps. If the distances of the various parallelsfrom each other and also of the meridians are all equal, we obtaina network of square meshes, as shown in equidistant flat maps. CYLINDER PROJECTIONS. 413 (Fi{ dwindling to zero, preserve the same length in all latitudes,while the meridians retain the natural length. This incon-venience is avoided in Mercators projection by increasing thedistances between the parallels toward the two poles at the sameratio that the parallels increase compared to the equator. () Mercators projection is well adapted to maps represent-
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