Like a traveler exploring some distant country, the wonders of which have hitherto been known only through reports and rumors of a vague or distorted character, so for four years have I been occupied in pushing an inquiry into a territory of natural knowledge which offers almost virgin soil to a scientific man. As the traveller sees in the natural phenomena he may witness the action of forces governed by natural laws, where others see only the capricious intervention of offended gods, so have I endeavored to trace the operation of natural laws and forces, where others have seen only the agency of supernatural beings, owning no laws, and obeying no force but their own free will. The phenomena I am prepared to attest are so extraordinary and so directly oppose the most firmly rooted articles of scientific belief--amongst others, the ubiquity and invariable action of the force of gravitation--that, even now, on recalling the details of what I witnessed, there is an antagonism in my mind between _reason_, which pronounces it to be scientifically impossible, and the consciousness that my senses, both of touch and sight--and these corroborated, as they were, by the senses of all who were present,--are not lying witnesses when they testify against my preconceptions. But the supposition that there is a sort of mania or delusion which suddenly attacks a whole roomful of intelligent persons who are quite sane elsewhere, and that they all concur to the minutest particulars, in the details of the occurrences of which they suppose themselves to be witnesses, seems to my mind more incredible than even the facts they attest. The subject is far more difficult and extensive than it appears. Four years ago I intended only to devote a leisure month or two to ascertain whether certain marvellous occurrences I had heard about would stand the test of close scrutiny. Having, however, soon arrived at the same conclusion as, I may say, every impartial inquirer, that there was "something in it," I could not, as a student of nature's laws, refuse to follow the inquiry wheresoever the facts might lead. Thus a few months have grown into a few years, and, were my time at my own disposal it would probably extend still longer.