I provided my friend with a packet of four plates, three of which had been exposed so that on being developed they would show a very conspicuous cross. At the seance two plates were first exposed and developed; on one appeared a cross with the portrait of the sitter, on the other appeared only the portrait. The photographer now knew that one plate at least was marked, and when the remaining two plates were exposed and developed the cross appeared on both of them.[25] There had been no substitution, but no spirit photographs either. Then the old excuse appeared--'one negative thought will spoil a whole circle', or, in other words, 'if you are on the watch for trickery we won't perform'. [Footnote 25: This is doubtful. My informant reported that he saw no cross on the last two plates, but when the four prints came to hand the cross appeared on three of them. Two prints were identical--though each was supposed to be from its own negative. If the photographer aimed at puzzling me he has succeeded.] It must be remembered that even in a 'good' seance only one or two spirit results may appear in several exposures, so the photographer can always expose, develop, and examine any or all of your plates, and at the least suspicion that yours are marked he may refrain from substituting his own prepared plates and blame the spirits for the lack of manifestations. One may ask why a private mark (say a faint file scratch on the edge) was not put on the plates so that the photographer himself could not detect, even after development, that they were marked in any way? Such a course would at once reveal whether substitution had taken place--though even then the real believer could declare that the spirits had removed the scratches. But this test is frustrated by the photographer--simple honest man--who refuses to part with the plates; he says they are now his property, but he will let you have some prints! In this example we find, as in so much 'evidential material', a point where investigation is blocked and credulity is demanded. Another piece of evidence is produced in this case, and I am shown a spirit photograph beside a lady's. The lady claims that the spirit is that of a young man, now deceased, to whom she was engaged. She was a stranger to the photographer, so how could he produce the likeness even if he substituted his own plates? But when I showed this spirit photograph to a friend, with a query as to sex, she answered, 'But it _is_ a woman, isn't it? It looks rather like N----.' Now N---- is a mature maiden lady, so that the sexless features of the spirit leave plenty of room for the play of fancy. We are invited to accept or disprove stories of spirit photography reported from the Continent, but whilst leading spiritualists in this country accept the productions of the man whose methods I have described I must refuse attention to anything they vouch for farther afield.