WHICH DO YOU WANT --
 (1) SAGITTA
 (2) RADIUS OF CURV.
 (3) SPHEROMETER SPAN
? 2
SPHEROMETER SPAN? 9876
BALL DIAMETER   ? 54
TYPE OF SURFACE --
  (1) CONCAVE
  (2) CONVEX
? 1
MEASURED SAGITTA? 1234
RADIUS OF CURVATURE  10524. 
MIRROR F.L.  5262. 
