By interpolation at th.e neighboring points one could assume the miss- 

 ing data to be given by 



( 2, 45) 



(39, 50) 



(44, 63) 



(45, 63) 



(46, 63) 



(45. 62) 



(46, 62) 



5. 15 

 5. 11 

 5.28 

 5.39 

 5. 59 

 5.43 

 5. 53 



The column vector B for Set 3 for the case in which N.,. is assumed 

 to be zero is given by 



/ 848,825.093 \ 

 B = 1,263, 519. 932 ] 



1 28, 687. 267 / ; 

 and if the interpolated points are used, B for Set 3 is given by 



848, 856. 34 



B= 1,263,558.44 



28,687.81 



The leveling equations for the two different ways of leveling each set 

 of data were actually obtained. The greatest difference in the two sets of 

 data between the two methods was -0.0 2 ft which was far below the level 

 of accuracy in the original spot heights. 



The preceding calculations were carried out on the Univac, a large 



87 



