A gold ring with a plain stone in it was the first odometer which I employed, and it is one of the most largely available. And gold forms in general the most successful Od-subject. Sulphur likewise displays very lively motions in the odometer. But the material which I finally employed to verify the following phenomena was shell-lac, a portion a full inch long, broader towards the lower end, then cut to be lancet-shaped. The odometer moves more sluggishly with some than with others, and in the same hand on different days; and doubtless is capable of manifesting a greater variety of effects than I have yet elicited from it. I can only pledge myself to the certainty of my being always now able to obtain with the shell-lac odometer all the results mentioned in the XXVII. experiments which first follow. Over rock-crystal, however, the shell-lac odometer acts very feebly; but a glass odometer moves with brilliant vivacity. I would besides advise the reader to try a gold-ring odometer, in preference, for experiments X., XI., XII., XIII. Then here are the results:— I. Odometer (we will suppose armed with shell-lac) held over three sovereigns heaped loosely together to form the Od-subject; the odometer suspended from the right forefinger of a competent person of the male sex. _Result_—Longitudinal oscillations. II. Let the experimenter, continuing experiment I., take with his unengaged hand the hand of a person of the opposite sex. _Result_—Transverse oscillations of the odometer. III. Then, the experiment being continued, let a person of the sex of the experimenter take and hold the unengaged hand of the second party. _Result_—Longitudinal oscillations of the odometer. IV. Repeat experiment I., and, the longitudinal oscillations being established, touch the forefinger which is engaged in the odometer with the forefinger of your other hand. _Result_—The oscillations become transverse. V. Repeat experiment I., and, the longitudinal oscillations being established, bring the thumb of the same hand into contact with the finger implicated in the odometer. _Result_—The oscillations become transverse. VI. Then, continuing experiment V., let a person of the same sex take and hold your unengaged hand. _Result_—The oscillations become again longitudinal. VII. Experiment I. being repeated, take and hold in your disengaged hand two or three sovereigns. _Result_—The oscillations become transverse. VIII. Continuing experiment VII., let a person of the same sex take and hold your hand which holds the sovereigns. _Result_—The oscillations become longitudinal. IX. If the odometer be attached to the thumb instead of to the forefinger, it oscillates longitudinally; but on approaching the thumb so as to touch the forefinger, the oscillations become of course transverse.