Your modern Spiritualist friend smiles when you tell him of these tricks. They are prehistoric. To-day you are allowed to examine the camera, bring your own plate, expose it and develop it yourself. The logic of the Spiritualist is here just as defective as ever. Because he has not on this occasion discovered certain forms of trickery which are now well known, he concludes that there was _no_ trickery. As if trickery did not evolve like anything else! Spiritualists were just as certain twenty years ago that there was no possibility of fraud because they brought their own marked plates; but they were cheated every time. There are still several ways of making the ghost. Where the sitter is careless, or an enthusiastic Spiritualist, the old tricks (substitution of plates, etc.) are used; but there are new tricks to meet the critical. The ghost may be painted in sulphate of quinine or other chemicals on the ground-glass screen. Such a figure is invisible when it is dry. There may be a trick dark-slide, with a plate which will appear in front of yours. If the photographer develops it for you, he can skilfully get a ghost on it by holding another plate against yours (pretending to see how it is developing) in the yellow light. If you develop it yourself, you use _his_ dish, which is often an ingenious mechanism. It has glass sides or a glass bottom, and, while the whole thing is covered up during development, secret lights impress the ghost on it. An actual case of this sort was exposed in _Pearson's Weekly_ on January 31, 1920. When the Spiritualist airily assures us that he has guarded against all these things (some of which could not be seen at all) we have to remember that Spiritualist literature teems with cases in which, we are told, "all precautions against fraud were taken," yet sooner or later the fraud is discovered. But the possibilities are not yet exhausted. I once saw a remarkable photograph which Sir Robert Ball had taken of the famous old ship, the _Great Eastern_. Along the side of it, in enormous letters, was the name "Lewis"; yet this name was totally invisible to the naked eye when one looked at the ship. A coat of paint had been put over the name--the ship had been used by Lewis's as an advertisement--and concealed it from the eye, yet the sensitive plate registered it. No scrutiny of the camera or the studio or the dark room would reveal conjuring of that sort. In fine, there is the possibility of some compound of radium, or radio-paint, being used at one or other stage in the process.