368 Penfield — Use of the Stereographic Projection ft 



or 



by the present writer in an earlier publication,* and at the 

 present time occasion will be taken to point out more specifi- 

 cally some of its defects. Figures 30, 31 and 32 represent 

 three maps of Africa, drawn about the same size and placed 

 side by side for ready comparison. Figure 31 is stereographic, 

 and drawn so as to show the continent, which is an especially 

 large one, with minimum distortion. Figure 30 shows the 

 continent as it appears near the periphery of the eastern hemi- 

 sphere in stereographic projection ; compare figure 9, page 258. 

 The continent being large, its northwestern lobe extends out 

 to that portion of the hemisphere, more than 85° from the 

 center, where the distortion for such a map is near a maximum, 

 see figure 19, page 272. Figure 32 differs from figure 30 in 

 that the projection is globular, and the lobe, which in the 

 former case was swelled out, is in this case unduly contracted, 

 so that thus quite an erroneous conception of the general pro- 

 portions of Africa is obtained. Notwithstanding distortion, it 

 is believed that figure 30 gives a better idea of the shape of 

 Africa than figure 32, as may be seen by comparison with 

 Africa on a globe, or on a map, such as shown in figure 31, 

 where the continent is represented with minimum distortion. 

 The superiority of the stereographic projection is still more 

 marked if the country represented on the map is a small one. 

 Figures 33 to 36 represent maps of Spain and Portugal drawn 

 with much care, the first three being stereographic, the last 

 globular. Figure 33 is based upon a hemisphere of 90 crn 

 (about 3 ft.) diameter, and shows the countries with minimum 

 distortion, 40° N., 4° W., being the point of tangency. Figures 

 34 and 35 are based upon hemispheres of 60 cra (about 2 ft.) 

 diameter, the first showing the countries as they appear on a 

 map of the Eastern Hemisphere, near the periphery, where 

 distortion is considerable; compare figure 9, page 258; the 

 second, as they appear on a map of the Northern Hemisphere, 

 where they are nearer the center than in the previous case, 

 consequently smaller and less distorted ; compare figure 4, page 

 252. For giving correct impressions of the shape and size of 

 the countries the three maps are about equally good. The 

 distances between the parallels furnish data for measurement ; 

 hence on any one of the three maps it may be seen that Spain 

 is about 7^-° or 450 geographical miles long from north to 

 south, and by measuring with dividers in an east and west 

 direction, the two countries together are about as broad as long. 

 To one accustomed to maps it does not much matter that in 

 figure 34 the countries are tilted, for the meridians give true 

 north and south. In contrast to these good maps, attention is 



* Loc. cit., page 126. 



