spond 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.

Notwithstanding thes