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NOMENCLATURE AND ANALOGIES 147<br />
the object alters its shape as it passes through it, let us<br />
suppose this film to run up to the contour of the object<br />
in every part, maintaining its plane surface unbroken.<br />
<strong>The</strong>n we can push a cube or any object through the<br />
film and the plane being who slips about in the film will<br />
know the contour of the cube just and exactly where<br />
the film meets it.<br />
Fig. 90 represents a cube passing through a plane film.<br />
<strong>The</strong> plane being now comes into<br />
Null<br />
Red<br />
Null<br />
White<br />
Pink<br />
Yellow<br />
Orange<br />
White Yellow<br />
Fig. 90..<br />
contact with a very thin slice<br />
of the cube somewhere between<br />
the left and right hand faces.<br />
This very thin slice he thinks<br />
of as having no thickness, and<br />
consequently his idea of it is<br />
what we call a section. It is<br />
bounded by him by pink lines<br />
front and back, coming from<br />
the part of the pink face he is<br />
in contact with, and above and<br />
below, by light yellow lines. Its corners are not nullcoloured<br />
points, but white points, and its interior is<br />
ochre, the colour of the interior of the cube.<br />
If now we suppose the cube to be an inch in each<br />
dimension, and to pass across, from right to left, through<br />
the plane, then we should explain the appearances presented<br />
to the plain being by saying: First of all you<br />
have the face of a cube, this lasts only a moment; then<br />
you have a figure of the same shape but differently<br />
coloured. This, which appears not to move to you in any<br />
direction which you know of, is really moving transverse<br />
to your plane world. Its appearance is unaltered, but<br />
each moment it is something different—a section further<br />
on, in the white, the unknown dimension. Finally, at the<br />
end of the minute, a face comes in exactly like the face