I will add in reference to the first and simplest experiments, that the interposition of several folds of silk between the Od-subject and the odometer renders the motions of the latter less brisk. The development which I have thus given to the few, isolated, and long-hoarded experiments of Herr Caspari, was not so simple an affair as it may seem to be. For several days I was in doubt as to the genuineness of the results, so capricious and contradictory were they. It was only when I had discovered, first, the reversing effect of touching the odometer finger with the thumb of the same hand, and, secondly, that approaching the thumb towards the odometer finger, or even allowing the other fingers of the odometer hand to close upon the ball of the thumb, has the same effect with bringing the point of the thumb into contact with the odometer finger, that I succeeded in obtaining unvarying results. The interest of these experiments is unquestionably very considerable. They open a new vein of research, and establish a new bond of connexion between physical and physiological science, which cannot fail to promote the advancement of both. They contribute a mass of objective and physical evidence to give support and substantiality to the subjective results of Von Reichenbach’s experiments. They tend to prove the existence of some universal force, such as that to which he has given theoretical form and consistence under the designation of Od. And such a universal force, what other can we deem it to be than the long-vilipended influence of Mesmer, rendered bright and transparent and palatable by passing through the filter of science? LETTER XIII. THE SOLUTION.—Examination of the genuineness of the phenomena—Od-motions produced by bodies in their most inert state—Analysis of the forces which originate them—Od-motions connected with electrical, magnetic, chemical, crystalline, and vital influences—Their analysis. The present letter might be entitled “An account of some motions recently discovered, to the manifestation of which an influence proceeding from the living human body is necessary.” The contrivance by which these motions are elicited I have called an Odometer, from the conviction that the force which sets it in movement is no other than the Od-force of Von Reichenbach. For the same reason I have called the objects with which it is tested Od-subjects, and the motions themselves Od-motions.