260 Penfield — Use of the Stereographio Projection for 



and from I to New York. Figure 11 illustrates another kind 

 of stereographic protractor, designated by the writer in an 

 earlier paper* as No. IV, and its use in finding any great 

 circle track, ^ as, for example, that from b to New York, is 

 almost too simple to need explanation. One has merely to 

 center the protractor and turn it until some great circle is 

 found which passes through the desired points or close to 



Stereographio Protractor adjusted for finding the great circle track from b 



to New York. Other great circles, H to M , M to a and a to b, have been 



drawn on the map. Great circles only are printed on the protractor. 



them. In order to measure the distances a protractor like the 

 one shown in figure 12 may be employed, and by using it the 

 distances to be sailed in going from Honolulu to New York 

 were found to be as follows : From H to M 103°, through the 

 Strait 5j°, from the Strait to a 37°, from a to b 17°, and from 

 b to New York 58^°, a total of 221°, or 13,260 geographical 



*Loc. cit., pp. 21 and 22. 



