14 
GIUSEPPE BIRARDI 
between planimetry and altimetry is negligible, due to the small angle between 
the axes Z and Z' ; this hypothesis generally occurs in practice. 
The calculation program envisages the following maximum dimensions : 
— 30 stretches, each including : 
. 20 known points, 
. 25 T points, 
. 50 calculation points ; 
— 500 known points in total, in the ground system. 
The storage size, however, would allow to raise up to 50 the number of stret 
ches ; the corresponding 1 : 25,000 coverage is about 2500 km 2 . 
First, the ground coordinates of the known points are stored. Then, the in 
strumental coordinates of all observed points are loaded ; the group of coordinates 
relative to each stretch is preceded by a heading card containing some data which 
are common to all points of the stretch itself (false origins, sphericity coefficients, 
etc.). 
Each point is identified by a serial nunber, whose last digit indicates its class 
(digit 1 for known points, 2 for T points, 3 for calculation points) ; as the machine 
reads the serial number, it carries out an analysis to establish its class. According 
to the result, the following procedures take place : 
— known point. The serial number coincident with the point’s number is 
sought for in the storage area where ground coordinates are contained ; the cor 
responding ground coordinates are stored in another storage area, in correspondence 
with the instrumental coordinates. The two observation equations of planimetry 
are then formed, and the normal system is incremented with the coefficients and 
the known terms. If among the known points there is not a serial number equal 
to that of the point under examination, the latter is handled like a calculation 
point ; 
— T point. Instrumental coordinates and serial number are stored in a 
proper storage area, large enough to contain all T points ; 
— calculation point. Instrumental coordinates and serial number are stored 
in a proper storage area. 
Once the storage of all points of a stretch is completed, the contents of the 
storage area concerning known and calculation points is transferred on magnetic 
tapes. 
As soon as the storage of all stretches is completed, the machine selects, for 
each T point, the corresponding point in the other stretches by the serial number ; 
then, for each couple, the observation planimetric equations are formed, and 
their coefficients and known terms are added to the normal system. This is 
solved, and for each stretch the 4 coefficients a, (3, X 0 , Y 0 and the scale factor 
s are obtained. 
When the planimetric adjustement is completed, for each stretch the known 
points coordinates are entered from the magnetic tape, and the observation equa