N((Di) 



cx=Normal Section Azimuth at Pi (from North) 



S = Arc length-Geodetic distance 



C = Chord lenqth, Pi Pz 



^=Angle of depression of C below horizon at Pi 



Ho=Maximum separation of arc S and chord C 



Figure 11. Relationship between arc length, normal section azimuth, chord length, 

 angle of depression of the chord below the horizon, maximum separation 

 of arc and chord. 



41 



