■13- 
length of one of the base board margins a 10 x 20 cms grid, 40 cms 
wide, was plotted. The center lines of the 1/20.000 control perma- 
trace bands were then aligned on the central axes of the grid on the 
board and the adjacent 20 cm grid points transferred. Similarly 
the axes of the double size bands were aligned and the outer 40 cm 
grid points transferred. 
The auxiliary grid points thus obtained were used on 
the scale transformation of the slotted templet control described 
later. 
6. 3 - Rectifier settings for 2x enlargement 
A 40 cm square was plotted on a piece of vinylite, using 
the A-7 coordinatograph. In order to avoid any possible backlash 
and eccentricity of the steel point holder, the final movements of 
the handwheels were always in the same rotation sense and the pri 
cker kept in unchanged position. 
The Wild E-3 rectifier was then adjusted by means of 
an A-7 grid plate, establishing the correspondance between the 20 cm 
glass plate square and the 40 cms square projected on the vinylite,. 
Thus the 5 freedom degrees of the rectifier were set to 
enlarge twice. 
All the 4 points coincided perfectly, which proves the 
good quality of the E-3 optics. 
6,4 - Enlargement of the radial triangulation control to l/lO.QOO 
With the rectifier in the previously determined posi 
tion, all the 9.5" wide permatrace bands were worked ou,t as if 
they were films and so all the slotted templet control - 1/20.000 - 
was enlarged to l/lO.OOO. 
The orientation of the 20" wide bands on the easel ta_ 
ble, was done successively for each set of nine points - correspond 
ding to a photograph - on the carry over points. 
The axes and auxiliary grid points were kept as much as 
possible in coincidence, to prevent cumulative errors. 
It was found necessary to ink in the slotted templet 
points on the 9".5 transparent bands. 
Although 6-12 meters long bands were used - scales 
1/20.000 and l/l0,000, respectively - the results obtained can be 
considered acceptable, as will be referred to later on.