surveyed not only in that the Earth’s curvature is eliminated but also because the 
z-component of every base is set to zero ignoring variations in flying height. 
The formula (46) gives the means for computing the base-component afterwards; 
it is the value to be used when plotting the model in question. 
Considering that for the method of triangulating described Abzi and A bz 
in formula (8) are corrections to zero to obtain bzi1 and bzi respectively, we may 
write: 
A bay. 4 = bai 4 A bzi — bzi 
(8) then becomes if we approximate bi by b: 
b^qi — bdqi — bzi 1 + bzi (47) 
or in view of (34) and (46): 
Ayı = 9/)— rr] 4 Ey Hilly + #F (0) (48) 
  
From (7) and (8) we derive a formula similar to (47): 
bA Di = bd qi 1— bzi m + bzi (49) 
or raising the index by one: 
b ^q/'i = bd qi E bzi - bzi+ 1 (50) 
The difference of (47) and (50) is: 
b (A qi — À qi’) = b (d qi — di) — bzi- a + 2 bai — bai +1 
From this formula and (44, for j =i) it follows: 
(pi + Api) — (pf + Ap!) — y (51) 
  
This formula shows that after the adjustment the difference between the 
longitudinal tilts of a photograph in two consecutive models is just the value 
required to eliminate the influence of the Earth’s curvature. 
It seems unnecessary to derive a formula for Ag/ similar to (48), this 
quantity being easily computed from (50). 
14. Adjusted coordinates x, y, z, of the x-transfer points. 
There is some practical advantage in computing adjusted coordinates in the 
machine system of the first model —1,0, which was adjusted to scale and into 
the horizontal, and computing from them the coordinates in the terrestrial 
system afterwards. This implies that we put provisionally: 
A Xo 7 0, A bye = 0, Xo = xo and Yo = Yo (52) 
a.  Abscissae. 
According to the definition given in chapter 3 the difference between the 
measured abscissae of two consecutive x-transfer points is the quantity 5’. Conse- 
quently the difference between the adjusted abscissae of these points is the adjusted 
quantity b" + db": 
Xj — Xi = b{ + dbf = x; — x's + db 
whence by successive summation over j — 12: 
x; = xi (xo xe) — [xj = xj], " [db Th 
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