hy Means of Graphical Methods. 



281 



right ano^les to xy fixes the pole of 100, which was fonncl to be 

 87° 5' ivom I, calculated 87° 6'. HaviDg located the pole 100, 

 the direction Oy' ^ parallel to xy^ may now be taken as the sec- 

 ond line of reference. Lines from :c to %0y\ both to the right 

 and left of the center, intercept the divided circle at 58° 50' 

 and 62° from —uu and angles eqnal to one-half of these valnes 

 29 30 



ioo. 



(paoje 260) o-ive the inclinations J A/" and V f\2^ namely, 29° 25' 

 and"31°, calculated 29° 29^ and 30° 58'. The indices of /and 

 z are therefore 130 and 130. The pole c, figure 30, was next 

 located from the measurements h /\c and rii/\c, small circles 

 about the poles I and on serving for tliis purpose. The small 

 circles are not shown in the figure, but that about J, having a 

 long radius, was constructed by means of tlie cmwed ruler,^ 

 that about m by means of a radius taken from scale Xo. 2 of 

 the sheets. _ Having located c, the great circles h,cf>' ; ?/?,<?,m'; 

 and 100,(?, 100 were drawn, thus determining the angles a, ,5, 

 * The Stereographic Projection and its Possibilities, loc. cit.. p. 12. 



