Fig. 2. Contour map of coal-heap. 
Measurings in Mines. 
In No. 17 an account is given of the use of photogrammetric methods 
to measure the walls and roofs in mines. The method was first applied in 
co-operation with an engineering firm to measure an old mine which 
was to be used as an oil-store. Both photo theodolites and the stereoscopic 
camera with a base of 120 cm were used at the photography. The latter 
appeared to be suitable for taking pictures of the roofs of the mine passa- 
ges. The plotting was made in the autographs A6 and A4 (the pictures of 
the stereo-camera). Later on the methods were applied to measurements 
in a larger mine at work. Here the pit-mouths were chiefly photographed. 
Deformation-measurements. 
At different occasions photogrammetric methods have been used to 
determine deformations of structures like bridges under heavy load. Single- 
picture methods have also been tried. This means that the object was 
photographed by a firmly fixed photo theodolite on one plate unlocaded 
and on another loaded. If the pictures were placed in a stereocomparator 
in such a way that possible deformations occurred as horizontal parallaxes 
even very small deformations could be stereoscopically observed and could 
be measured with high accuracy. 
  
  
  
  
grapl 
ting \ 
By 
plotti 
make 
In 
of a 
static 
a ste 
with 
by t: 
Se 
to de 
be u 
of 1 
oriel 
used 
slow 
cate 
has 
Tc 
num 
intei 
plac 
oper 
lam] 
the | 
blac 
pair 
con 
T 
gast 
mat 
sill 
The