a ii 
  
  
  
  
  
  
T 
not used as height control and do not in fact affect 
   
   
  
It is emphasized, however, that points on the coast line were 
the final 
depths of any points lying between the north and south tie strips, . 
Final determination of heights 
This then completed the work except that the depths of all 
the points below the common elevated horizontal needed to be reduced 
to heights above sea level, This was a simple datum correction 
effected by subtracting the depths of a sea level point from the 
depths of all the other points, The determined heights were then 
compared with the values of the height controls. 
Results were as follows: 
The standard mean square error of ‘all height determinations was 
) & 
" 
LL 
" 
11.9 feet, 
.( points or 28% were in error by 5 feet or less 
160 " " 61% " " 1 1 10 " " 
24 1 or "n 84 % tt " t n" 1 5 " i 
21.5 " " 9 96 " " T It. 20 " tt 
252 " " 97% " : " "n " 25 " tt 
260 " "4 00% " " " " 28 " " 
These results were considered sufficiently good as a basis for 
50 feet contouring. 
—] Ti STRP!