"I may add that, if in one example I have negligently omitted corroborative inquiries, I am not in the habit of sparing pains to authenticate a narrative. You imagine that I have been satisfied with the reports in Spiritual papers about the 'Electric girl.' I spent a week in Paris in procuring the original documents in that case and embodying them in my narrative. A small portion only of these is contained in the 'Comptes Rendus.' The authentic details have never yet been given to the American public. They are of great interest in a scientific point of view. "You assume that such men as Arago regard clairvoyance as mere trickery. Arago, in 1853, expressly said ('Footfalls,' p. 23) that 'somnambulism ought not to be rejected _a priori_, especially by those who have kept up with the progress of modern science;' and he admitted ('Footfalls,' p. 68) that 'psychology may one day obtain a place among the exact sciences.' Cuvier went further. He conceded ('Footfalls,' p. 68) the principle lying at the base of Mesmerism. "Inasmuch as my book treats only of spontaneous phenomena, not of those that are evoked, I have therein said nothing of the Foxes, except in connection with the narrative of what, in the olden time, would have been called the 'haunted house' of Hydesville; one of a class of which I have given numerous other older examples. Now, however, having been afforded by the sisters ample opportunity to investigate the rappings and other manifestations alleged to occur in their presence, I am ready, after warning, to go farther, and to say that, whatever the true character of these phenomena, I see no reason whatever for ascribing them to imposture. Nothing came to light in the course of this investigation other than what bore, to my mind, the impress of an honest desire to be freed, by rigid tests of fair dealing, from all blame. I never rest my opinion of character or motive upon report when I can have opportunity of personal verification. Such opportunity, which in this case I believe you have not had, I am enabled now to offer you. I am authorized by Mrs. Underhill (formerly Leah Fox) and by her husband (a gentleman of New York who has been, for seventeen years, secretary of one of the principal insurance offices in Wall Street), to say that, though Mrs. Underhill has not for some years sat as a professional medium, and has resolved not again to do so, she is willing, in the interests of truth, to afford you, during the university vacation, or at other time when your leisure serves, all reasonable facilities for strict investigation. "I pray it may not be understood that I urge you to accept this offer. I think, indeed, that such an investigation is not unworthy either of your character or of mine. But I am no propagandist; and I have observed that if there be nothing within which moves us to undertake such inquiries, they seldom afford satisfaction or eventuate in useful results.