“Next, it is taken for granted that the rappings are not produced by artificial contrivances about the persons of the females, which may be concealed by the dress. This hypothesis is excluded because it is understood that the females have been repeatedly and carefully examined by lady committees.

“It is obvious that the rappings are not caused by machinery attached to tables, doors, etc., for they are heard in different rooms, and in different parts of the same room in which the females are present, but always near the spot where the females are stationed. This mechanical hypothesis is then to be excluded. So much for negative evidence, and now for what positively relates to the subject.

“On carefully observing the countenances of the two females it is evident that they involve an effort of the will. They evidently attempted to conceal any indications of voluntary effort, but did not succeed. A voluntary effort was manifested, and it was plain that it could not be continued very long without fatigue. Assuming, then, this positive fact, the inquiry arises, how can the will be exerted to produce sounds (rappings) without obvious movements of the body? The voluntary muscles themselves are the only organs, save those which belong to the mind itself, over which volition can exercise any direct control. But contractions of the muscles do not, in the muscles themselves, occasion obvious sounds. The muscles, therefore, to develop audible vibrations, must act upon parts with which they are connected. Now, it was sufficiently clear that the rappings were not vocal sounds; these could not be produced without movements of the respiratory muscles, which would at once lead to detection. Hence, excluding vocal sounds, the only possible source of the noises in question, produced as we have seen they must be, by voluntary muscular contractions, is in one or more of the movable articulations of the skeleton, from the anatomical construction of the voluntary muscles. This explanation remains as the only alternative.

“By an analysis prosecuted in this manner we arrive at the conviction that the rappings, assuming that they are not spiritual, are produced by the action of the will, through voluntary action on the joints.

“Various facts may be cited to show that the motion of the joints, under certain circumstances, is adequate to produce the phenomena of the rappings; but we need not now refer to these. By a curious coincidence, after arriving at the above conclusion respecting the source of the sounds, an instance has fallen under our observation, which demonstrates the fact that noises precisely identical with the spiritual rappings may be produced in the knee-joints.

“A highly respectable lady of this city possesses the ability of developing sounds similar, both in character and degree, to those professedly elicited, by the Rochester impostors, from the Spirit world. We have witnessed the production of the sounds by the lady referred to, and have been permitted to examine the mechanism by which they are produced. Without entering at this time into a very minute anatomical and physiological explanation, it is sufficient to state that the muscles inserted into the upper and inner side of the large bone of the leg (the tibia), near the knee-joint, are brought into action so as to move the upper surface of the bone just named laterally upon the lower surface of the thigh bone (the femur), giving rise, in fact, to a partial lateral dislocation.[10] This is effected by an act of the will, without any obvious movement of the limb, occasioning a loud noise, and the return of the bone to its place is attended by a second sound. Most of the Rochester rappings are double. It is practicable, however, to produce a single sound by moving the bone out of place with the requisite quickness and force, and allowing it to slide slowly back, in which case it is noiseless.

“The visible vibrations of articles in the room, situated near the operator, occur, if the limb, or any portion of the body, is in contact with them at the time the sounds are produced. The force of the semi-dislocation of the bone is sufficient to occasion distinct jarring of the doors, tables, etc., if in contact. The intensity of the sound may be varied in proportion to the force of the muscular contractions, and this will render the apparent source of the rappings more or less distinct.

“We have witnessed repetitions of experiments, in the case just referred to, sufficient to exhibit to us all the phenomena of the sounds belonging to the Rochester rappings, and, without further explanations at this time, we append our names in testimony of the facts contained in the foregoing hastily penned exposition.

“Austin Flint, M. D.,}University
“Charles A. Lee, M. D.,of
“C. B. Coventry, M. D.,Buffalo.

“February 17, 1851.”