76 
265, 267, 272, 275, 286, 297, 298 and 299. The distribution of the chosen ground 
control points is schematically shown in Fig. 1. 
It is unfortunate that some of these ground control points left much to be desired 
as far as identification is concerned. The choice of the above listed points was made 
on the basis of their situation; and we had no idea about the quality of these points 
when the selection was made. 
Fig. 1 
To connect the successive models in each strip, at least three pass points were 
selected. The marginal pass points in the adjacent strips also served as tie points 
between the strips. Pass points also served to tie the secondary strips to the main 
strips. 
2.2. Triangulation of the Autograph Wild Al. — The Wild A7 autographs of 
The Ohio State University, Columbus, Ohio, and of Cornell University, Ithaca, 
New York, were used to undertake the aerotriangulation of Block Massif Central. 
The triangulation was executed according to the « Folgebildanschluss » Method, as 
an aeropolygon. The relative orientation was made according to the von Gruber's 
Assymetrical Method. 
Considerable difficulty was encountered in identifying several test point. The 
following points were not identifiable (N.I.) because of the following stated reasons, 
and, thus, were not measured: 
Points not marked on the paper prints: 1, 2, 44, 45, 74, 75, 76, 116, 117, 151, 
152, 156, 196, 197, 233, 234, 235, 269, 270. 271, 285, 300. 
Points for which no sketch was provided: 16, 23, 71, 185, 247, 260. 
Points not stereoscopically covered: 114, 115, 198. 
Points unidentifiable because of vagueness of sketches: 132, 195, 261.