The fourth dimension

NOMENCLATURE AND ANALOGIES 155

find that the position his squares are to be placed in will lie below that which they first occupied. They will come where the support was on which he stood his first set of squares. He will get over this difficulty by moving his support.

Then, since the cubes come upon his plane by the light yellow face, he will have, taking the null cube as before for an example, null, light yellow face; null, red section, because the section is perpendicular to the red line ; and finally, as the null cube leaves the plane, null, light yellow face. Then, in this case red following on null, he will

Null Null ‘ ca wh nwa a“ + Ks N : 4 qe aS ° I 2 Null ; \

Fig. 95.

have the same series of views of the red as he had of the null cube.

There is another set of considerations which we will briefly allude to.

Suppose there is a hollow cube, and a string is stretched across it from null to null, 7, y, wh, as we may call the far diagonal point, how will this string appear to the plane being as the cube moves transverse to his plane ?

Let us represent the cube as a number of sections, say 5, corresponding to 4 equal divisions made along the white line perpendicular to it.

We number these sections 0, 1, 2, 3, 4, corresponding to the distances along the white line at which they are