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.
X. Repeat experiment I., but let the Od-subject be a double row of five sovereigns, each disposed longitudinally from you, and hold the odometer over the middle of the double row of sovereigns. Result—Longitudinal oscillations, but the excursions are inordinately long. Still, on touching the forefinger with the thumb, the oscillations become either transverse, or the odometer moves in an ellipse, of which the long axis corresponds with the axis of the double line of sovereigns.
XI. Dispose ten sovereigns longitudinally from you in two parallel rows, an inch and a half apart, and hold the odometer over the middle of the interval. Result—Longitudinal oscillations.
XII. Modify experiment XI. by holding the odometer not midway, but nearer one of the rows of sovereigns. Result—Oblique oscillations.
XIII. Dispose ten sovereigns heaped in a short longitudinal group, and hold the odometer over the table half an inch to one side of the middle of the heap. Result—Transverse oscillations.