Hinton conceived of an electric current as a four-dimensional vortex.  He declared that on the Higher Space Hypothesis the revolution of the ether would yield the phenomenon of the electric current.  The reader is referred to Hinton’s book, The Fourth Dimension, for an extended development of this idea.  What follows is a brief summary of his argument.  First, he examines the characteristics of a vortex in a three-dimensional fluid.  Then he conceives of what such a vortex would be in a four-dimensional medium of analogous properties.  The whirl would be about a plane, and the contour of this plane would correspond to the ends of the axis line in the former vortex; and as before, the vortex would extend to the boundary.  Every electric current forms a closed circuit:  this is equivalent to the hyper-vortex having its ends in the boundary of the hyper-fluid.  The vortex with a surface as its axis, therefore, affords a geometric image of a closed circuit.

Hinton supposes a conductor to be a body which has the property of serving as a terminal abutment to such a hyper-vortex as has been described.  The conception that he forms of a closed current, therefore, is of a vortex sheet having its edge along the circuit of the conducting wire.  The whole wire would then be like the centers on which a spindle turns in three-dimensional space, and any interruption of the continuity of the wire would produce a tension in place of a continuous revolution.  The phenomena of electricity—­polarity, induction, and the like—­are of the nature of the stress and strain of a medium, but one possessing properties unlike those of ordinary matter.  The phenomena can be explained in terms of higher space.  If Hinton’s hypothesis be the true explanation, the universality of electro-magnetic action would again point to the conclusion that our three-dimensional world is superficial—­the surface, that is, of a four-dimensional universe.

THE GREATER UNIVERSE

This practically exhausts the list of accepted and accredited indications of hyper-dimensionality in our physical environment.  But if the collective human consciousness is moving into the fourth dimension, such indications are bound to multiply out of all measure.  It should be remembered that in Franklin’s day electricity was manifest only in the friction of surfaces and in the thunderbolt.  To-day all physical phenomena, in their last analysis, are considered to be electrical.  The world is not different, but perception has evolved, and is evolving.

There is another field, in which some of our ablest minds are searching for evidences of the curvature of space, the field of astronomy and astro-physics.  But into this the layman hesitates to enter because the experts themselves have found no common ground of understanding.  The ether of space is a battlefield strewn with dead and dying hypotheses; gravitation, like multiplication, is vexation; the very nature of time, form and movement is under vivid discussion, in connection with what is known as the Theory of Relativity.