such a way that the point to be measured shall be brought within the circle of 
10 mm in diameter marked on the glass plate directly under the pricking needle 
and then X', Y', X", and Y" shall be precisely adjusted so as to bring the mea 
sured point of the stereo model to coincidence with the floating mark by the aid 
of observation through the optical system. In this case the stereo model shall be 
adjusted by rotating (K\ K") the Amici prisms mentioned in (A) (1).) 
(C) Pricking Needle 
( a ) After the measured point is brought to coincidence with the floating mark 
by the aid of stereoscopic observation, the said point on the diapositive 
shall be pricked. In pricking, a minimotor is used as the power source in 
order to maintain the uniform size of the pin hole and its form. 
( b ) The pricking needle is operated in the following steps: 
(1) A push-button switch shall be pressed for a short time (neary 1/2 second) 
and then released. 
(2) If the push-button is pressed, the opal glass for illumination will be in- 
staneously turned outside from its position directly under the pricking 
needle. 
(3) After the opal glass will have completed its turning away, the mini 
motor will start to operate. 
(3) After once started, the mini-motor will be switched on the power source 
by means of a cam and continue its revolution. (Then the push button 
may be released.) 
(4) After once started, the mini-motor will be switched on the power source 
by means of a cam and continue its revolution. (Then the push button 
may be released.) 
(5) The pricking needle standing by at its top position will descend slowly 
rotating by itself with the rotation of the motor until its tip will touch 
the emulsion surface and it will make nearly three complete revolutions 
and then slowly ascend until it will reach the top position. 
(6) As soon as the pricking needle will reach the top position, the motor 
will be switched off by itself by means of the cam and brought to a 
stop. 
(7) After the pricking needle will reach its top position, it will assume a 
stand-by attitude for the next operation and it will come to stop after 
completing one revolution for pricking (for nearly four seconds). 
( c ) A balance weight is attached to the pricking needle in order to make it 
lighter. The pressure given by this balance weight to the emulsion sur 
face is adjustable. (When the tip of the pricking needle touches the 
emulsion surface, the film base may be free from scratch when film is 
used whereas the tip of the needle may be free from damage when dry 
plate is used by the aid of making the weight of the pricking needle 
properly light. Specifically when film is used, if the needle would prick 
its base, the material of the base would rise around the pin-hole, or would 
make its density change; therefore, if the base would be looked at its 
back, the pin-hole looks indistinct because of refraction of light occurred 
thereabout. In consequence, it is necessary to prick the pin-hole only on