g to the 
axes, the 
rt rod in 
ss of the 
les of its 
nall irre- 
diameter 
ecked by 
lon chan- 
lve inter- 
rods cur- 
m (right 
3 
12 pm 
  
— 19 — 
2) Strarghtness of the short rod. — T he short rod was subjected to a 
ries of similar tests, with a view to ensuring, by means of the same equip- 
ii hat the terminal hole of the short rod, into which can be inserted the 
Sent t he mechanical correction of the objective distorsions, is coaxial. 
um Sd fig. 13/b shows the findings of the tests, which were satisfac- 
tory too. 
Left Right 
  
ft P d 
CX © © 
> @ «5 
  
  
: 
N 
  
  
  
  
  
  
Fig. 13/5 - Curvature of the short rod. 
| | i : 1 were globally check neasur- 
The 4 bearings which guide the short rod were globally checked, mea 
ing the respective shiftings between the arm to which the bearings are con- 
nected and the short rod, during its travel along its axis. This method ena- 
bled to simultaneously check the taper of the short rods. The evident perio- 
dicity of the irregularities of the experimental shifting curve shows the Dre 
sence of motion anomalies in the bearings of the order of 3 to 4 y m. 'Thes 
have no dangerous influence on projection, and the taper is negligible. 
3) Excentricity between the axes of the Cardan coupling. —'l'he anomalies 
| i ink hown 
which may occur in the construction of the Cardan link of the rod are shown, 
€Xag 
a 
b 
gerated for illustring purposes, in fig. 14. They are as follows: 
i Ss 7 i axes; 
excentricity between the primary and the secondary rotation a 
Il 
excentricity between the short rod and the primary axis;