[10] We have now been tracing upon a spherical surface the region which we state to be occupied by the habitable earth; and whoever would represent the real earth as near as possible by artificial means, should make a globe like that of Crates, and upon this describe the quadrilateral within which his chart of geography is to be placed. For this purpose, however, a large globe is necessary, since the section mentioned, though but a very small portion of the entire sphere, must be capable of properly containing all the regions of the habitable earth, and presenting an accurate view of them to all those who wish to consult it. Any one who is able will certainly do well to obtain such a globe. But it should have a diameter of not less than ten feet: those who cannot obtain a globe of this size, or one nearly as large, had better draw their chart on a plane- surface, of not less than seven feet. Draw straight lines, some parallel, for the parallels [of latitude], and others at right angles to these; we may easily imagine how the eye can transfer the figure and extent [of these lines] from a plane-surface to one that is spherical. What we have just observed of the circles in general, may be said with equal truth touching the oblique circles. On the globe it is true that the meridians of each country passing the pole have a tendency to unite in a single point, nevertheless on the plane- surface of the map, there would be no advantage if the right lines alone which should represent the meridians were drawn slightly to converge. The necessity for such a proceeding would scarcely ever be really felt. Even on our globe itself1 the tendency of those meridians (which are transferred to the map as right lines) to converge is not much, nor any thing near so obvious as their circular tendency.
1 The artificial globe of 10 ft. diameter.
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