highly
attenuated expansion of air, gas, or other matter, having all the
functions of ordinary matter. Whewell has, indeed, published a
_demonstration_ that all matter is ponderable, and that imponderable
matter is not a conceivable idea. Be this as it may, the diversity of
opinion on this point shows the difficulty the mind finds in departing
from the truths of phenomena to the uncertainties of hypothesis; but if
hypothesis be justifiable, which it is only on the ground of absolute
necessity to link together, and render conventionally intelligible,
certain undoubted, undeniable facts, which have been associated together
under the terms _electricity_, _magnetism_, &c.--how difficult and
dangerous it must be when the facts which it seeks to associate are
denied by the mass of thinking men, when they are confessed to be
mysterious and irregular by their most strenuous advocates, each of whom
differs, in many respects, as to these facts!

These difficulties have by no means been conquered by Mr Townshend. At
p. 11, he objects to this mode of theorizing, in the following strong
terms:--

"A certain school of German writers especially have theorized on
our subject, after the false method of explaining one class of
phenomena in nature by its fancied resemblance to another. Wishing,
perhaps, to avoid the error of the spiritualists, who solve the
problem in debate by the power of the soul alone, they have
ransacked the material world for analogies to mesmerism, till the
mind itself has been endued with its affinities and its poles. Such
attempts as these have done the greatest disservice to the cause we
advocate. They submit it to a wrong test. It is as if the laws of
light should be applied to a question in acoustics. It is as if we
should expect to find in a foreign kingdom the laws and customs of
our own."--(P. 11.)

And yet, in the subsequent parts of his book, he asserts mesmerism to be
capable of "reflection like light"--to have "the attraction of
magnetism"--to be "transferred like heat;" to escape from a point like
electricity, and to have the sympathetic undulations of sound!--(Pp.
335, 6, 7, and 8.)

Such general resemblances as the following are given:---

"We know that electricity is capable of all that modification in
its action which our case demands. Sometimes its effects are sudden
and energetic; sometimes of indefinite and uninter