If we work with a physical medium of even only average force, raps will be heard after the third or fourth seance. They will be heard much sooner if we have a powerful medium. As a rule, raps seem to resound on the top of the table; but it is not always so. They are frequently heard on the ground, on the sitters, or on the furniture, walls, or ceiling. The raps I have heard—of course I am speaking only of genuine raps—have resounded near the medium, as a rule, either on the table, floor, walls, or furniture in close proximity to him. The simplest way to obtain raps is to proceed as I have directed in section ii. chapter 1. The experimenters, seated around a table, lay their hands upon it palm downwards, with outstretched fingers. This method is not, however, to be strongly recommended, for raps are easily imitated: and we must never lose sight of that fact when appreciating an experiment; further on, I will enumerate the usual fraudulent processes. Still, even when the hands are resting upon the table, raps can be obtained of sufficient sonority to exclude the hypothesis of fraud, if not absolutely, at least with much probability. I have received raps in full light. I have received them so frequently in vivid light, that sometimes I cannot help wondering, whether darkness facilitates their production to the same extent as it may other phenomena. It is, however, allowable to suppose, that the energy which produces them prefers accumulating force in spots that are sheltered from strong light, _e.g._ under the table, or under the floor, or in shaded corners of the room. What makes me suppose so is this, I have frequently noticed that the raps burst forth under the medium’s hand, when they appeared to be produced on the top of the table. Contact of the hands is unnecessary when sitting for raps. I have procured them quite easily, with several mediums, without such contact. When we have succeeded in obtaining raps with contact, one of the best ways of obtaining them without contact is to let the hands rest for a certain time on the table, then to raise them _very slowly_, palms downwards, and the fingers loosely extended. Under such conditions, it seldom happens that raps do not continue to be heard for at least a short time. I need not say that experimenters should not only avoid contact of their hands with the table, but even of any part of their body or clothing. The contact of clothing with the table is sufficient to produce raps, which have nothing of a supernormal nature. We must be careful, therefore, that ladies’ dresses especially do not come into contact with the table; in taking these necessary precautions, raps can be obtained under most satisfactory and convincing conditions.