[Footnote 1: A sketch of the history will be found in the author's _Cock Lane and Common Sense_.] [Footnote 2: The best source is his article on 'Poltergeists.' _Proceedings_ xi. 45-116. See, too, his 'Poltergeists' in _Studies in Psychical Research_.] [Footnote 3: _Studies in Psychical Research_, p. 140.] [Footnote 4: See Preface to this edition for correction.] [Footnote 5: _Proceedings_, S.P.R. vii. 383-394.] [Footnote 6: See Sir W. Crookes's _Researches in Spiritualism_.] [Footnote 7: Mr. Aïdé has given me this information. He recorded the circumstances in his Diary at the time.] [Footnote 8: _Report of Dialectical Society_, p. 209.] [Footnote 9: See Porphyry, in Parthey's edition (Berlin, 1857), iii. 4.] [Footnote 10: _Bulletin de la Société de Biologie_, 1880, p. 399.] [Footnote 11: Crookes, _Proceedings_, ix. 308.] APPENDIX C _CRYSTAL-GAZING_ Since the chapter on crystal-gazing was in type, a work by Dr. Pierre Janet has appeared, styled 'Les Névroses et les Idées Fixes.'[1] It contains a chapter on crystal-gazing. The opinion of Dr. Janet, as that of a savant familiar, at the Salpêtrière, with 'neurotic' visionaries, cannot but be interesting. Unluckily, the essay must be regarded as seriously impaired in value by Dr. Janet's singular treatment of his subject. Nothing is more necessary in these researches than accuracy of statement. Now, Dr. Janet has taken a set of experiences, or experiments, of Miss X.'s from that lady's interesting essay, already cited; has attributed them, not to Miss X., but to various people--for example, to _une jeune fille, une pauvre voyante, une personne un peu mystique_; has altered the facts in the spirit of romance; and has triumphantly given that explanation, revival of memory, which was assigned by Miss X. herself. Throughout his paper Dr. Janet appears as the calm man of science pronouncing judgment on the visionary vagaries of 'haunted' young girls and disappointed seeresses. No such persons were concerned; no such hauntings, supposed premonitions, or 'disillusions' occurred; the romantic and 'marvellous' circumstances are mythopoeic accretions due to Dr. Janet's own memory or fancy; his scientific explanation is that given by his trinity of _jeune fille, pauvre voyante_, and _personne un peu mystique_. Being much engaged in the study of 'neurotic' and hysterical patients, Dr. Janet thinks that they are most apt to see crystal visions. Perhaps they are; and one doubts if their descriptions are more to be trusted than the romantic essay of their medical attendant. In citing Miss X.'s paper (as he did), Dr. Janet ought to have reported her experiments correctly, ought to have attributed them to herself, and should, decidedly, have remarked that the explanation he offered was her own hypothesis, verified by her own exertions.