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.