The human "aura" itself should be made the subject of special study. Here is a perfectly tangible thing, so to speak, which physicists can work on to their hearts' content, without becoming "contaminated" by the general run of psychic manifestations! Is the aura a form of physical radiation? Does it affect the atmosphere? Can it be photographed? Is it connected with the phenomena of exteriorization of sensitivity or motivity? Will it affect the galvanometer needle, or other delicate electrical or physical instruments? Is it connected with the "astral" or "etheric body"? What is its condition when the subject is asleep? Can it be altered at will? Is it affected by passing a high-tension current through the body of the subject? (We know that these high-tension currents will themselves create an electric aura around the body.) What becomes of the aura after death; and what changes, if any, does it undergo at the moment of death? Such are a few of the questions which the psychic student might ask himself, and which certainly call for solution. Once more: is "psychometry" a fact? If objects can retain certain "influences" within them, what is their nature, and how are they retained? How does the sensitive perceive these impressions? Is there not a connection between these phenomena and haunted houses? or between the "charging-up" of a table or planchette board before it proceeds to answer questions and behave in the manner it is often reported to do? What is the nature of the "cold breeze" which is so often experienced, not only at seances, but during very many psychic phenomena, both of the experimental and spontaneous types, in all parts of the world? Is it a physical breeze, or is it purely "psychical"? Could it be collected and analysed, as was suggested in the case of the cold breeze issuing from the scar on Eusapia Palladino's forehead? What is its source? And what is its object? On this subject alone much suggestive and valuable research might be undertaken. Take the simple phenomena of _raps_. What produces them? What is the bond between the hand of the medium which makes a gesture in the direction of the table, and the table itself? What is the nature of the physical impact upon the table? Are these raps due to exteriorized vital force? If so, does this energy exude from the nerve termini, or is it connected only with the etheric body or double? Can these raps be controlled at will, or directed and controlled when the subject is under hypnosis? Can this energy be directed at will? Could it not impress delicate physical instruments? Might not a connection be thus established between these phenomena and the impressions of hands and faces, etc., occasionally seen in the presence of Eusapia and other mediums?