[Footnote 14: It is not possible to eliminate the operation of such preferences in the percipient. But if care be taken that the series of things to be guessed is chosen arbitrarily, the only effect of even a decided preference for particular cards, numbers, etc., on the part of the percipient will be to lessen the number of coincidences due to thought-transference.] CHAPTER II. EXPERIMENTAL TRANSFERENCE OF SIMPLE SENSATIONS IN THE NORMAL STATE. It is somewhat remarkable that the facts of thought-transference should only have attracted serious attention within the last two decades. With waking percipients, indeed, such phenomena do not seem to occur unsought with sufficient frequency, or--if we leave on one side for the moment telepathic hallucinations--on a sufficiently striking scale to afford evidence of any transmission of thought or sensation otherwise than through the familiar channels. But the hypnotic state appears to offer peculiar facilities for such transmission, and hypnotism, under the name of mesmerism, has now been closely studied by numerous observers for upwards of a century. The earlier French observers,[15] indeed, occasionally recorded instances of what appears to have been thought-transference between the mesmerist and his subject. But these facts were observed by the way, in the search for phenomena of another kind; and no attempt appears to have been made to follow up the clue by means of direct experiment. Even the English observers of 1840 and onwards, though familiar with what they termed "community of sensation" between the operator and his subject, appear never to have realised its possible significance. Dr. Elliotson, for instance, describes in the _Zoist_ (vol. v. pp. 242-245) some experiments in which a lady, mesmerised by himself, was able to indicate correctly the taste of salt, cinnamon, sugar, ginger, water, and pepper, as Dr. Elliotson placed successively these various substances in his mouth. But he seems to have recorded the results chiefly from curiosity, and to have regarded them as of little scientific interest compared with the stiffening of a limb, or the painless performance of an operation under mesmeric anæsthesia. Dr. Esdaile (_Practical Mesmerism_, p. 125), Mr. C. H. Townshend (_Facts in Mesmerism_, pp. 68, 72, 76, etc., etc.), Professor Gregory (_Animal Magnetism_, p. 231), and other writers of that time, record similar observations. But the subject seems to have been crowded out, on the one hand, with the more cautious observers, by the growing importance of hypnotism as an anæsthetic and a curative agency, on the other by the greater marvels of "clairvoyance" and "spirit" communications.