Parties to experiments with the odometer may be in the position either of Od-subjects, or of reversers of its effects in the hands of others, or they may be themselves components of the odometer. I can discover absolutely no difference in the results obtained by the odometer on men and women, when treated as Od-subjects. The following results appear to me equally obtainable with persons of both sexes. With the exception of the arms below the elbows, the wrists and hands, and of the legs below the knees, the ankles and feet, the two sides of the person display the polar differences already noticed. If the odometer be held over the right side of the head, (either front or back,) over the right side of the face, over the right shoulder or elbow, or right knee, it exhibits clock-rotation. Held over the same parts on the left side, it exhibits versed-rotation. On touching the odometer-finger with the thumb, these effects are of course reversed. If the odometer be held over the middle and outside of either arm, or over the middle and back of either fore-arm or hand, it oscillates longitudinally and towards the hand or foot. On reapplying the thumb, these longitudinal oscillations are replaced by transverse oscillations, having a direction _outwards_—_i. e._, away from the mesial plane of the frame. The phenomena last described show that the primary idea of a transverse polarity for the whole frame is still verifiable, even in the extreme parts of either limb. But below the elbows and knees a second polarity is superinduced upon the former. Below the elbows and knees, one side of each limb repeats the phenomena of the right side of the body, the other those of the left. The odometer held over the tips of the fingers of either hand exhibits clock-rotation, over the thumb of either hand versed-rotation; and with these, as I have mentioned, all the other effects that can be elicited out of the two limbs of a horse-shoe magnet. The same rotatory movements may likewise be obtained by holding the odometer near the two edges of the hand, wrist, fore-arm. The latter singularity, which contrasts with the simpler effects on the upper arm, must result from the combination of the two polarities—the systemic and the submembral one. The odometer, held over the back of the neck or throat, oscillates transversely. When versed, longitudinally. It appears to me now that women generally are incapable of eliciting the movements of the odometer when held by themselves, without touching a second party. I have already, in the introductory part of this letter, given a summary of all the modes I am acquainted with of reversing the motions of the odometer.