( 6 ) Width of contour in z - direction. 
From the figure 7, we know that the width of the contour in the 
z - direction is large. This phenomena genise on account of the slits’ 
width is large in the =z - direction as is shown in Fig.20 . 
Therefore, the precision of the contour depends on the width of the 
alit, ‘especially dn the z= direction. 
If the cone be cut by the vertical-plane light beam g , the intersec- 
tion between the cone and the plane light beam is a hyperbola 1,, and 
i, represents another hyverbola by the plane beam f. 
CN 
Namely, the point P where the lines cross each other. The arc ? % 
e ? 
X ^S 
and RB are photographed on the plate, nevertheless we want to take a 
photograph only & point p 
As we know in the figure 2^, the Length FG, and P'4, depend on the 
angle y, the width of" the contour in the  z - direction becomes a 
function ofthe direction cosines. The direction cosines are of a 
small-tangential plane 4f at any point on the surface of the object, and 
T0. and qa depend on the direction cosines of the vertical plane 
light beam. Therefore, thereisalimit of precision without any 
contrivance in application of this method and then author will represent 
the following plan . 
FURTHER ATTEMPT CONSIDERABLE 
Author has an intention of making the apparatus that can record the 
coordinates of each points on & contour. 
In Figi22, D ds/tne rotating drum , which has man: photo-transistors 
on its surface, and the drum is carried with the slit Sl. 
p P P P, represent the photo-transistor respectively. 
And they correspond to the Y - coordinates as follows 
  
  
And 
on 
dru 
thr 
in 
sel 
Fig 
REF 
xx 
XXX