Now, at this point, an inquirer, who had not pre-judged the question, and who did not believe his own knowledge of the universe to be so complete as to justify him in rejecting all evidence for facts which he had hitherto considered to be in the highest degree improbable, might fairly say, “Your evidence for the appearance of visible, tangible, spiritual forms, is very strong; but I should like to have them submitted to a crucial test, which would quite settle the question of the possibility of their being due to a coincident delusion of several senses of several persons at the same time; and, if satisfactory, would demonstrate their objective reality in a way nothing else can do. If they really reflect or emit light which makes them visible to human eyes, _they can be photographed_. Photograph them, and you will have an unanswerable proof that your human witnesses are trustworthy.” Two years ago we could only have replied to this very proper suggestion, that we believed it had been done and could be again done, but that we had no satisfactory evidence to offer. Now, however, we are in a position to state, not only that it has been frequently done, but that the evidence is of such a nature as to satisfy any one who will take the trouble carefully to examine it. This evidence we will now lay before our readers, and we venture to think they will acknowledge it to be most remarkable. Before doing so it may be as well to clear away a popular misconception. Mr. Lewes advised the Dialectical Committee to distinguish carefully between “facts and inferences from facts.” This is especially necessary in the case of what are called spirit photographs. The figures which occur in these, when not produced by any human agency, may be of “spiritual” origin, without being figures “of spirits.” There is much evidence to show that they are, in some cases, forms produced by invisible intelligences, but distinct from them. In other cases the intelligence appears to clothe itself with matter capable of being perceived by us; but even then it does not follow that the form produced is the actual image of the spiritual form. It may be but a reproduction of the former mortal form with its terrestrial accompaniments, _for purposes of recognition_. Most persons have heard of these “ghost-pictures,” and how easily they can be made to order by any photographer, and are therefore disposed to think they can be of no use as evidence. But a little consideration will show them that the means by which sham ghosts can be manufactured being so well known to all photographers, it becomes easy to apply tests or arrange conditions so as to prevent imposition. The following are some of the more obvious: