io. 
The masonite sections were nailed so that their june-» 
tions would not coincide with those of the structure, thus preven 
ting, as much as possible, deformations caused by temperature chan 
ges, In addition, room temperature was conditioned. 
The grid was set out with a Wild T2 theodolite and a 
beam compass coupled with an accurate metallic scale allowing mea 
surements to minus 5 hundredths of a millimetre (Alteneder instru 
ments). 
The theodolite was stationed on one of the base board 
corners using a cast iron base plate. The rectangular axes were 
then defined by means of several pins. As the theodolite only al 
lows focussing for distances longer than 5 feet, and the centering 
bubble pin which fits into the base plate does not permit the sta 
tion to be pricked to less than 1 millimeter, and this accuracy is 
definitely unacceptable, the following method was resorted to: 
Y 
s 
Fig.1. 
r 
Two straight lines r and s, slightly inclined in rela 
tion to the X and Y directions, were defined by stationing the the 
odolite on the two contiguous vertices of the base board. 
Measuring the distances between the points 
P r .P fc and the point S 1 and the ordinates Y fc of the points Pp..P k , 
it is possible to determine, by Analytical Geometry, the ordinates 
Yp of the points Sp, thus allowing the extension of the axes as 
needed. 
This was done via the following formula: 
n 
K-J. 
V Jt-1 
n 
where Y^=Y - m S., P, 
where Ip-Y^. m °.p that is , Y^ are the ordinates of each one 
oP the points S , computed from the points P^ (K =1 ... n) and 
i k i