-10- 
In equations 1, 1’ and 2, jJL and represent the mean square 
error in planimetry and elevations due to triangulation and adjustment 
of a single strip. If the block is composed of tie (main) strips in 
addition to the filler (secondary) strips, the mean square error in 
planimetry and elevations of spot points would be approximately equal 
respectively (since the triangulation and adjust- 
ment are undertaken on the main strips first, then on the secondary 
strips). 
In addition to the errors due to aerotriangulation, one should, 
of course^,take all other sources of error into consideration. Such 
errors are those involved in the operations of identification, ground 
control, plotting and drafting. 
point P due to aerotriangulation and its adjustment (equal 
to jUt in case of single strips, and fJL\j ¿_ in case of blocks 
having tie and filler strips), 
|_j is the mean square residual error in the elevation of a 
point due to aerotriangulation and its adjustment (equal 
to /^[_j in case of single strips, and^|_|{2in case of block 
having tie and filler strips), 
is the total mean square residual error in the position of 
a point p, 
is the total mean square residual error in elevation of a 
point p, 
is the mean square error in the position of a point due to 
transformation of coordinates,