rties, in which the light waves vibrate _transversely_
to their direction, it assists the mind to think of the ether as
four-dimensional, because then a light wave would be a superficial
disturbance of the medium--superficial, but three-dimensional, as
must needs be the case with the surface of a four-dimensional solid.

* * * * *

This search for evidences of hyper-dimensionality in the universe
accessible to our senses is like looking, not for a needle in a
haystack, but for a haystack in a needle--for the greater in the less.
From the purely physical evidences, all that can with certainty be
said is that the hypothesis is not inconsistent with the facts of
science or its laws; that it is being verified and rendered more
probable by the investigations of science; that it is applicable to
the description or explanation of all the observed phenomena, and
assigns a cause fully adequate to have produced them.

Now there is an order of phenomena that we call psychic. Because
they are phenomenal they cannot occur outside of time and space
altogether; because they are psychic they defy explanation in terms
of the space and time of every-day life. Let us next examine these
in the light of our hypothesis.

IV TRANSCENDENTAL PHYSICS

ZOeLLNER

In the year 1877, Johann Friedrich Zoellner, professor of physics and
astronomy at the University of Leipsic, undertook to prove that
certain (so-called) psychic phenomena were susceptible of explanation
on the hypothesis of a four-dimensional space. He used as
illustrations the phenomena induced by the medium Henry Slade. By
the irony of events, Slade was afterward arrested and imprisoned for
fraud, in England. This fact so prejudiced the public mind against
Zoellner that his name became a word of scorn, and the fourth dimension
a synonym for what is fatuous and false. Zoellner died of it, but
since his death public opinion has undergone a change. There is a
great and growing interest in everything pertaining to the fourth
dimension, and belief in that order of phenomena upon which Zoellner
based his deductions is supported by evidence at once voluminous and
impressive.

It is unnecessary to go into the question of the genuineness of the
particular phenomena which Zoellner witnessed. His conclusions are
alone important, since they apply equally to other manifestations,
whose authenticity has never been successfully impeached. Zoellner's
rea