of experiments, from fifteen to eighteen hundred in number, which occupied me nearly fifteen months. The results of above twelve hundred were written down at the time of their performance."

The scene of the Count's operations was in the valley of the Loire, five leagues from Vendôme, in the park of the Chateau de Ranac. The surface of ground which gave the desired results was from seventy to eighty feet in breadth. But there was another spot equally efficient at the Count's ordinary residence at Emerillon, near Clery, four leagues south of Orleans, ten leagues south of the Loire, at the commencement of the plains of Solonge. The surface ran from north to south, and had the same breadth with the other. These "exciting tracts" form, in general, bands or zones of undetermined, and often very great, length. Their breadth is very variable; some are only three or four feet across, while others are one hundred paces. These tracts are sometimes sinuous; in other instances they ramify. To the most susceptible they are broader than to those who are less so.

M. de Tristan thus describes what happens when a competent person, armed with a hazel-fork, walks over the exciting districts :

When two or three steps have been made upon the exciting tract of ground, the fork, which at starting is held horizontally, with the point forwards, begins gently to ascend; it gradually attains a vertical position; sometimes it passes beyond that, and lowering itself, with its point to the chest of the operator, it becomes again horizontal. If the motion continues, the rod descending becomes vertical, with the point downwards. Finally, the rod may again ascend and resume its first position. When the action is very lively, the rod immediately commences a second revolution; and so it goes on,

as

long as the operator continues to walk over the exciting surface of ground.

A few of those in whose hands the divining fork moves, exhibit a remarkable peculiarity. The instrument, instead of commencing its motion by ascending, descends; the point then becomes directed vertically downwards; afterwards it reascends, and completes a revolution in a course the opposite of the usual one; and as often and as long as its motion is excited, it pursues this abnormal course.

Of the numerous experiments made by M. de Tristan, the following are among the simplest and the best :

He covered both handles of a divining rod with a thick silk stuff. The result of using the instrument so prepared was the same which Mr Fairholm obtained by coating the handles with sealing-wax. The motion of the divining rod was extinguished.

He covered both handles with one layer of a thin silk. He then found that the motion of the divining rod took place, but it was less lively and vigorous than ordinary.

By covering one handle of the divining rod, and that the right, with a layer of thin silk, a very singular and instructive result was obtained. The motion of the instrument was now reversed. It commenced by descending.

After covering the point of the divining rod with a thick layer of silk stuff, the motion was sensibly more brisk than it had been before.

When the Count held in his hands a straight rod of the same substance conjointly with the ordinary divining rod, no movement of the latter whatsoever ensued.

Finally, the Count discovered that he could cause the divining rod to move when he walked over a nonexciting surface-as, for instance, in his own chamber -by various processes. Of these the most interesting consisted in touching the point of the instrument with

either pole of a magnetic needle. The instrument shortly began to move, ascending or descending, according as the northward or southward pole of the needle had been applied to it.

It is unnecessary to add that these, and all M. de Tristan's experiments, were repeated by him many times. The results of those which I have narrated were constant.

Let me now attempt to realise something out of the preceding statements.

1. It is shown by the testimony adduced, that whereas in the hands of most persons the divining rod remains motionless, in the hands of some it moves promptly and briskly when the requisite conditions are observed.

2. It is no less certain that the motion of the divining rod has appeared to various intelligent and honest persons, who have succeeded in producing it, to be entirely spontaneous; or that the said persons were not conscious of having excited or promoted the motion by the slightest help of their own.

3. It appears that in the ordinary use of the divining rod by competent persons, its motion only manifests itself in certain localities.

4. It being assumed that the operator does not, however unconsciously, by the muscular action of his hands and wrists produce the motion of the divining rod, the likeliest way of accounting for the phenomenon is to suppose that the divining rod may become the conductor of some fluid or force, emanating from or disturbed in the body by terrestrial agency.

But here a difficulty arises: How can it happen that the hypothetical force makes so long and roundabout a course? Why, communicated to the body through the legs, does not the supposed fluid complete a circuit at once in the lower part of the trunk?

Such, at all events, would be the course an electric current so circumstanced would take.

The difficulty raised admits of being removed by aid derived from a novel and unexpected source. I allude to the discovery, by Von Reichenbach, of a new force or principle in the physical world, which, whether or not it is identical with that which gives motion to the divining rod, exhibits, at all events, the very property which the hypothetical principle should possess to explain the phenomena which we have been considering.

No attempts have indeed been made to identify the two as one; and my conjecture that they may prove so, should it even appear plausible, is so vague, that I should have contented myself with referring to Von Reichenbach's new principle as to an established truth, and have introduced no account of it into this Letter, had I not a second motive for insuring your cognisance of the curious facts which the Viennese philosopher has brought to light. It is less with the view of furnishing a leg to the theory of the divining rod, than in order to provide the means of elucidating more interesting problems, that I now proceed briefly to sketch the leading experiments made by Von Reichenbach, and their results.

Objections have been taken against these experiments, on the ground that their effects are purely subjective; that the results must be received on the testimony of the party employed; and that the best parties for the purpose are persons whose natural sensibility is exalted by disorder of the nerves; a class of persons always suspected of exaggeration, and even, and in part with justice, of a tendency to trickery and deception. But this was well known to Von Reichenbach, who appears to have taken every precaution necessary to secure his observations against error. And when I add, that many of the results which he obtained upon the most sensitive

and the highly nervous, were likewise manifested in persons of established character and in good health, and that the fidelity of the author and of his researches is authenticated by the publication of the latter in Woehler and Liebig's Chemical Annals, (Supplement to volume 53, Heidelberg, 1845,) I think you will not withhold from them complete reliance.

In general, persons in health and of a strong constitution are insensible to the influence of Von Reichenbach's new force. But all persons, the tone of whose health has been lowered by their mode of life-men of sedentary habits, clerks, and the like, and women who employ their whole time in needlework, whose pale complexions show the relaxed and therefore irritable state of their frames-all such, or nearly all-evince more or less susceptibility to the influence I am about to describe.

Von Reichenbach found that persons of the latter class, when slow passes are made with the poles of a strong magnet moved parallel to the surface-down the back, for instance, or down the limbs, and only distant enough just not to touch the clothes-feel sensations rather unpleasant than otherwise, as of a light draft of air blown upon them in the path of the magnet.

In the progress of his researches, Von Reichenbach found that the more sensitive among his subjects could detect the presence of his new agent by another sense. In the dark they saw dim flames of light issuing and waving from the poles of the magnet. The experiments suggested by this discovery afford the most satisfactory proofs of the reality of the phenomena. They were the following:-A horse-shoe magnet having been adjusted upon a table, with the poles directed upwards, the sensitive subject saw, at the distance of ten feet, the appearance of flames issuing from it. The armature of the magnet—a bar of soft iron-was then applied. Upon