As to the _rapping noises_, we are inclined to think they may have something to do with the knee and toe joints, and that the two performers usually sit together, in order the better to alternate with, and _spell_ or relieve each other. Upon a fair trial, it certainly has been proved that the noises cannot be produced when the joints are grasped firmly by another. But it may be doubted by some whether the joints can be made to produce the distinct rappings that are sometimes heard. We think they can. A few years ago, a boy in London gave exhibitions of what was termed "_chin music_." It was done by striking the fists upon the lower jaw. By this practice he was able to produce quite loud and distinct sounds, and play a variety of tunes, to the amusement of the public. The sounds were made by the finger joints, it was supposed; and perhaps the jaw bone may have contributed its share in the performance. The sounds given by the "rapping spirits" are by no means so remarkable as many suppose. They are often quite indistinct, and nearly inaudible. Unless a person was possessed of a large share of credulity, he would never consider them as the responses of an intelligent spirit. This is the decided conviction of hundreds who have witnessed their performances in various parts of the country. Yet many have been, and others will be, deceived. And, doubtless, many tender and sensitive minds may be made insane by the wicked trifling of these unprincipled impostors. Certainly we have not the least desire to set at nought any thing of a _truly serious_ character. Yet we are constrained to believe that the things of which we have spoken are too ridiculous and nonsensical, if not actually _sinful_, to be entitled to the least favor from the public. The learned Thomas Dick, in his Essay on the Improvement of Society, gives an account of far more singular and wonderful _phenomena_ produced by _mechanical_ agency, than any that has as yet been attributed to the agency of _spirits_, as affirmed by A. J. Davis, or La Roy Sunderland. And we here subjoin the facts of the case, for the benefit of the public:--