Pierson, Tick, and Baer 



In order that each grid point will represent approximately the same area, a 

 multiple -projection system was developed. This will keep the maximum distor- 

 tion on each segment of the projection relatively small. But, the problem of 

 bridging between the segments of the multiple-projection is thus introduced. 

 The system, named an "icosahedral-gnomonic projection," is a separate gno- 

 monic projection," is a separate gnomonic projection on each face of an icosa- 

 hedron circumscribed about the earth. A similar projection was described by 

 Fisher (26) but emphasized land and was therefore not suitable for the present 

 use. 



Various properties of one of these triangular gnomonic projections are 

 listed in Table 1. Figure 7 illustrates the areal distortion relative to 1.00 of 

 the location of mean areal distortion for an equilateral triangular projection. 

 Note that the distortion ranges only from -19% to +62% at the extremes and this 

 positive extreme applies only to the apexes. 



Table 1 

 Properties of the Gnomonic Projection on a Face of an Icosahedron 



Assumes a spherical earth of radius 3440.19 nautical miles (from Ref. 25), 



514 



