Geographical Maps and Sailing Charts. 269 



possibilities in mathematical geography. Maps of the hemi- 

 spheres two feet in diameter would not be too large for con- 

 venient use, and they could be engraved with such accuracy 

 that remarkably exact measurements could be made on them. 



Stereographic Map including more than a Hemisphere. — 

 All of the inhabited portions of the world may be shown on 

 one map, as illustrated by figure 15, which is a stereographic 

 projection on the plane of the equator, copied from a figure 

 given by (x. W. Littlehales,* with omission of some of the 



16 









W II IB* 



1 \ ^ 





\3| 







jv"* 



~6o - 



~io 



-2oM^ 





r*\ 



20 ^^ 

 / 4° 





Model for illustrating the principle of the stereographic projection upon a 

 plane at right angles to a given diameter. 



details. The projection extends from the north pole to 60° 

 south of the equator, and distortion on a map covering so large 

 an area is very great. Although the land areas in the southern 

 hemisphere appear grotesquely stretched out, they are prob- 

 ably no more distorted than Greenland on Mercator's projec- 

 tion. It is not suggested that maps of this kind should be 

 used ; the illustration is introduced merely to show some of 

 the possibilities of the projection. 



Stereographic Projection upon the Plane of a Horizon. — 

 A most important feature of the stereographic projection is 



* The Development of Great Circle Sailing, loc. cit., p. 50. 



