The fourth dimension

REMARKS ON THE FIGURES 201

sections of the successive planes into which we analyse the cutting space would be a tetrahedron of the description shown (fig. 123), and the whole interior of the tetrahedron would be light brown.

Noy

Noy Front view. The rear faces, Fig. 127.

In fig. 127 the tetrahedron is represented by means of its faces as two triangles which meet in the p. line, and two rear triangles which join on to them, the diagonal of the pink face being supposed to run vertically upward,

We have now reached a natural termination. The reader may pursue the subject in further detail, but will find no essential novelty. I conclude with an indication as to the manner in which figures previously given may be used in determining sections by the method developed above.

Applying this method to the tesseract, as represented in Chapter IX., sections made by a space cutting the axes equidistantly at any distance can be drawn, and also the sections of tesseracts arranged in a block.

If we draw a plane, cutting all four axes at a point six units distance from null, we have a slanting space. This space cuts the red, white, yellow axes in the