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 forearm 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, forearm. 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.

Perhaps I have presumed too much in heading this letter with the title of "The Solution." But what is the solution of physical phenomena but the displaying of the forces which compel their sequence? As an inquiry progresses, a few general expressions take the place of the first imperfect and complicated explanation. But the first step made was still a solution; and the highest solution ever yet obtained has probably still to be merged in some expression yet more general. So the attraction of gravitation is probably connected with, or balanced by, a corresponding repulsive force, coming into operation at some enormous distance from the centre of each planetary sphere, and the two may eventually prove to form one law.

But I had hoped that I was not presuming in asserting that the present inquiry has immediate practical applications, such as seldom fall to the lot of so young an investigation. The odometer may prove a useful test of the presence and qualities of electric, chemical, and magnetic actions; it will probably help to determine

the electro-chemical qualities of bodies; and in large or small crystalline masses-in the diamond, for instancewill serve to show the axes and distinguish the opposite poles. In reference to biology, it will probably furnish the long-wanted criterion between death and apparent death; for I observe that, with an egg long kept, but still alive, though no longer likely to be very palatable, the odometer freely moves in the way described in the fourth section. But it treats the freshest egg, when boiled, as if it were a lump of zinc.

Nevertheless I am not without certain misgivings. I suspect that the divining-ring will be found to manifest genuine od-motions in the hands of as small a number as succeed with the divining-rod. And I fear that overhasty confidence in results only seemingly sound, may lead many astray into a wide field of self-deception.

POSTSCRIPT.

An accident has given me the opportunity of making further additions to this little volume, of which I proceed to avail myself; and, first, by communicating my latest experiments with the divining-ring, July 24.

I. I have stated that, if a fresh egg be placed upon the table, with the small end directed from me-or a crystal, with one definite pole so turned from me-or a bar-magnet, with its northward pole so disposed-and I then suspend the divining-ring half an inch above either of the three so averted ends, and half an inch further off from me, the ring exhibits clock-rotation in each instance. Held in a parallel manner over the opposite ends—that is, half an inch from, and half an inch higher than, the same-the ring exhibits versed-rotation. If

the three od-subjects be moved round, so that their hitherto distal ends point to the right, or if they be further turned, so as to bring the previously distal ends now to point directly towards me, the ring continues to exhibit exactly the same motions as in the first instance.

If, these objects being removed, I lay a horse-shoe magnet on the table before me, with its poles turned directly from me, the northward limb being on my left hand, the southward limb-pole on my right, and experiments parallel to those just described are made, the results remain the same. If, near one side of the horseshoe magnet, I lay my left hand on the table, the palm downwards, the thumb held wide of the fingers, the ring, if suspended half an inch from and above either of the finger-points, displays clock-rotation; suspended similarly before and above the point of the thumb, versedrotation. Or the fingers of the left hand, so disposed, may be compared, in reference to od, to the northward pole of a horse-shoe magnet, while the thumb corresponds with its southward pole.

If, removing my left hand, I turn the horse-shoe magnet, without altering the side on which it rests, half round, so that the poles point directly towards me, the northward pole being now, of course, on my right, the southward pole on my left, the ring held as before over either of the two poles, displays the same results. If I now move the magnet still nearer to me, so that its two poles are an inch beyond the edge of the table, I can obtain results which furnish a more precise explanation of the two rotatory movements already described, than I had before arrived at.

If I now suspend the ring, with its lowest part on a level with the magnet, and half an inch from its northward pole—that is, half an inch nearer me—it begins to oscillate longitudinally, with a bias towards me, as if it

were repelled from the pole of the magnet. If I then suspend the ring an inch vertically above the first point of suspension, it begins to oscillate transversely, with a bias towards the right, or as if impelled by a dextrad current. If I then lower the ring half an inch, the first effect observed is, that it oscillates obliquely, being evidently impelled at once to the right and towards methat is, in the diagonal of the two forces, of each of which I had before obtained the separate influence. In this third variation of the experiments, I have brought the ring to the limit of the two currents, where both tell upon it. This oblique oscillation soon, however, undergoes a change it changes into clock-rotation, showing that the transverse or dextrad current is stronger than the longitudinal or proximad current.

If parallel experiments be made at levels below that of the pole of the magnet, corresponding but opposite results ensue. If the whole series be repeated upon the south pole of the magnet, opposite but perfectly corresponding results are again obtained: and similar results may be obtained with the two poles of an egg.

II. The mode in which I have latterly educed the rotatory movements depending upon galvanism, has been this. I have laid two discs, one of zinc, the other of copper, one on the other, having previously moistened their surfaces with salt and water. Then, as I mentioned, the ring held over the middle of the zinc disc (that being uppermost) exhibits clock-rotation. Held over the middle of the copper disc, when that is laid uppermost, versedrotation. I mentioned, too, that if held beyond, but near the circumference of the same discs, the direction of the motion of the ring is reversed.

The discs which I employ are circular, an inch and a half in diameter, and about as thick as a sovereign.