The fourth dimension

CHAPTER VIII

THE USE OF FOUR DIMENSIONS IN THOUGHT

Havine held before ourselves this outline of a conjecture of the world as four-dimensional, having roughly thrown together those facts of movement which we can see apply to our actual experience, let us pass to another branch of our subject.

The engineer uses drawings, graphical constructions, in a variety of manners. He has, for instance, diagrams which represent the expansion of steam, the efficiency of his valves. These exist alongside the actual plans of his machines. They are not the pictures of anything really existing, but enable him to think about the relations which exist in his mechanisms.

And so, besides showing us the actual existence of that world which lies beneath the one of visible movements, four-dimensional space enables us to make ideal constructions which serve to represent the relations of things, and throw what would otherwise be obscure into a definite and suggestive form.

From amidst the great variety of instances which lies before me I will select two, one dealing with a subject of slight intrinsic interest, which however gives within a limited field a striking example of the method

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