We have already given numerous examples of the effects produced by impressions on the retina by mechanical appliances. We can now in a short chapter speak of the cause of many spectral illusions, commonly supposed to be “ghosts” or “spirits.” That there are many “well-authenticated ‘ghost stories’” no one can doubt who has read the literature of the day; and we ourselves do not in any way desire to throw any doubt upon the existence of certain so-called “ghosts.” That appearances of some kind or another are seen by people we know. We ourselves have seen such, but we cannot say we believe in the popular ghost. In ancient times mirrors were much employed by the so-called magicians, and in our day many wonderful ghost effects have been shown at the (late) Polytechnic Institution. Some people are believers in table-turning and spiritualism, and mesmerists still attract large audiences, and appear to possess extraordinary power over some individuals. But apparitions have been seen by people eminently worthy of credit. The experience of the learned Doctor, which appeared some months ago in the _Athenæum_, is a case in point. This narrative is concise and clear. The spectre was there. How did it get there? Was the “appearance” objective or subjective? Let us give an extract from the Reverend Doctor’s narrative, and comment upon it afterwards. We may premise that Dr. Jessopp had gone over to Lord Orford’s (Mannington Hall), and at eleven o’clock was busy writing in the library, and was “the only person downstairs.” We will give this ghost story in the Doctor’s own words. After taking up a certain volume—time about 1 a.m.:— “I had been engaged on it about half an hour, and was beginning to think my work was drawing to a close, when, as I was actually writing, I saw a large white hand within a foot of my elbow. Turning my head, there sat a figure of a somewhat large man with his back to the fire, bending slightly over the table, and apparently examining the pile of books that I had been at work upon.”... After describing the appearance of the nocturnal visitor, Dr. Jessopp proceeds:— “There he sat, and I was fascinated; afraid not of his staying, but lest he should go. Stopping in my writing I lifted my left hand from the paper, stretched it out to the pile of books, and moved the top one—my arm passed in front of the figure, and it vanished.”... Shortly after the figure appeared again, and “I was penning a sentence to address to him, when I discovered I did not dare to speak. I was afraid of the sound of my own voice! There he sat, and there sat I. I turned my head and finished writing. Having finished my task, I shut the book, and threw it on the table; it made a slight noise as it fell;—the figure vanished.”