30 
of a slider on a bench. The illuminations must be brighter, and although instead 
of sending perfect plane beams we can do with image forming of slits, the breadths 
of the slit images on the intersection line must be always constant. In the pro 
cess of this time the latter is consistent in principle, but actually the performance 
seems to be imperfect. As to the illumination there need more improvements to 
be made in future. 
The real principle applicable to these intentions is as follows. In Fig. 1 L 0 , 
Li, and L-2 represent three lenses of the same properties and set in a plane L. S 0 , 
S u and S 2 are slits all parallel to each other and perpendicular to the plane of the di 
agram and fixed on a plane rigid body S which is parallel to L. For brevity let us as 
sume the lenses L 0 , L u and L 2 to be thin, and call the centers of them by the same 
letters Lo, L\, and L 2 . The relation among the points L 0 , L u and L 2 and the slits S 0 , 
Si, and S 2 is such that the planes S 0 ~L 0 , Si~L u and S 2 -L 2 intersect each other on a 
linear line I that is perpendicular to the plane of the diagram. It will be clear 
from the fundamental law of triangle, that if this condition is once fulfilled, any 
lateral motion of S in its own plane such as shown with arrows makes I move in 
a plane F parallel to S as shown with other arrows, the property that I is the 
common intersection line of the three planes being kept. It must be mentioned 
here that the plane F on which I moves and the plane S are made to conjugate 
to each of the three lenses concerned, and the photographic plate P is set just 
behind S at a fixed position. The plate S is shifted with a slider mounted on a 
optical bench, and it suffices for the connected motion of the three planes, promis 
ing to minimize the inaccuracy coming from the mechanism mentioned before. 
We must, however, admit that we are too optimistic in the optical consideration. 
In order to get a clear photographic result through this process, it is clear, the 
angles /.SJSo and ¿S 2 IS 0 must not be very small, because the intersection line 
of two planes is decided definitely only when the angle between them is fairly 
large. When we put an object rightly in front of the photographing lens L 0 , 
this fact prohibits the illuminating plane beams from being paraxial, whereas we