26 
upper cardanic joints (perspective centres), small microscopes with xl2 magnification 
are attached (figs. 17, 18). These microscopes, provided with bifilar hairlines, can be 
adjusted such that the distances from the perspective centres, to the lower cardanic joints 
are equal on both space rods. 
Fiducial lines are provided for the following distances: 190 mm, 152 mm and 89 mm. 
IV. 2 Ster eometrograph D of VEB Zeiss Jena. 
The Stereometrograph D is the successor of the model C, with some extensions and impro 
vements. These are: 
1) . extension to super-wide angle photography ( c ran g e = 87 - 215mm), 
2) . extension of the model space (XYZ, AZ rai ^ e = 350mm), 
3) . possibility of recording bx-, by-, bz- (with Coordimeter); special output for by-; by 
disconnecting Z, the instrument can be used as a comparator (X, Y,bx,by), 
4) . several new auxiliary devices have been constructed: 
a) , optical correction plates for lens distortion, 
b) . improved magnetic switch for the tracing pencil, 
c) . drawing unit for small circles (el. driven) for marking points, 
d) . automatically controlled tracing head for plotting of different dashed lines, 
e) . double tracing carriages for plotting along edges of two adjacent sheets simultane 
ously, 
f) . attachable mirror and magnifying glass for the tracing pencil (facilitates observation 
from the operator's place), 
g) . setting projector (profiloscope) with a measuring mark on the screen - facilitating 
settings on points on the drawing table from the operator's place (cross-sections), 
h) . device showing the location of the measuring mark on one of the photographs (for 
closed instruments). A photograph is placed on a (luminous) surface 25x25cm. Only 
the section corresponding to the location of the measuring mark is illuminated. 
IV. 3 Extensions of the Wild Aviographs B8 and B9 
The Aviograph B8 has been provided with improved plotting devices and, for numerical 
restitution, with an automatic coordinate recording unit. 
The pole of the pantograph is attached to an adjustable arm above the XY-datum plane, such 
that a map sheet can be placed under it. This facilitates the utilisation of map sheets up to 
lxlm without the necessity of bending them. The range of transmission ratios is between 
2:5 and 5:2, and can be changed in 19 steps. 
For plotting in reduced scales, a stable precision pantograph has been constructed - not re 
quiring a special drawing table. It is adapted for the transmissions between 5:4 and 5:1. 
For the purpose of numerical restitution, an automatic coordinate recording device has been 
developed. The lower cardanic joint, connecting the two space rods, is attached to an X, Y,H