This theory of the psychic transparency is very popular just now and is being freely invoked to account for the obvious indications of fraud which even a superficial study of spirit photographs reveals. It is expounded at some length by the Rev. Chas. L. Tweedale (_Light_, January 22nd, 1921), who carefully describes the various indications which show clearly that the extra is often produced by a transparency of _some_ kind, in terms which could be used almost without alteration as proof of the fraudulent nature of the productions. Thus the edges of the “psychic” transparency are said to be clearly visible on many of Hope’s negatives, and we are told that “in some cases when ‘the cotton-wool effect’ is introduced, this ring of nebulous whiteness probably forms the edge of the transparency and ... may conceal its use.” Most astonishing of all, perhaps, is this author’s credulity in accepting as genuine a spirit photograph showing two portraits of the late Mr. Stead of which one was an exact duplicate of the other, but larger, and clearly showed the “screen effect” of small dots which one can observe in any printed reproduction of a photograph.[15] Certainly there is ample evidence to show that some kind of transparency is frequently used in the production of extras (_Cf._ p. 18 above), especially by Hope, but there seems no reason to suppose that it is in any way “psychic.” On the contrary, a friend of mine who enjoyed the privilege of a sitting with this artist not long ago tells me that when he went to focus the camera (as one is frequently invited to do), he clearly saw a wholly gratuitous face already projected on the ground-glass! Now either there was some kind of an objective apparition present in the camera’s field of view which reflected light which only became visible after passing through the lens (which is absurd), or there was a transparency of some kind between the lens and the ground-glass. Of course it _may_ have been a psychic transparency born before its time--one cannot possibly say definitely that it was not, but the more mundane inference seems very much the more probable. In fact, all this talk of The Problems of Psychic Photography is no more than an orgy of hypothetising from a mass of utterly unreliable data. If only believers in spirit photographs would take the trouble to learn a little more about fraud and tighten up their control accordingly, instead of inventing strange hypotheses to bolster up their imperfect observations, we should hear less of photographic mediums and fewer people would be duped in this deplorable fashion. IX.--REAL TEST CONDITIONS (W. WHATELY SMITH)