a faculty of perceiving and indicating subterraneous springs and currents by sensation. The term is modern, and derived from Mr Bleton, who for some years past has excited universal attention by his professing the above faculty, which seems to depend upon some peculiar organization. Concerning the reality of this extraordinary faculty, there occurred great doubts among the learned. But M. Thouvenel, a Frenchman of some consequence and a philosopher, seems to have put the matter beyond dispute, in two memoirs which he has published upon the subject. He was charged by the king with a commission to analyse the mineral and medicinal waters in France; and, by repeated trials, he had been so fully convinced of the capacity of Bleton to assist him with efficacy in this important undertaking, that he solicited the ministry to join him in the commission upon advantageous terms. All this shows that the operations of Bleton have a more solid support than the tricks of imposture or the delusions of fancy. In fact, a great number of his discoveries are ascertained by respectable affidavits. The following is a strong instance in favour of Bletonism. "For a long time the traces of several springs and their reservoirs in the lands of the Abbé de Verriens had been entirely lost. It appeared, nevertheless, by ancient deeds and titles, that these springs and reservoirs had existed. A neighbouring abbey was supposed to have turned their waters for its benefit into other channels, and a law-suit was commenced upon this supposition. M. Bleton was applied to; he discovered at once the new course of the waters in question: his discovery was ascertained, and the law-suit was terminated."

Bleton has been mistaken more than once; and our author enumerates, with the fairest candour, the cases in which he has failed: but these cases are very rare in comparison with those in which he has succeeded. Besides, even the mistakes of Bleton do not invalidate the reality of his talent; since a talent may be real without being perfect, or exerting itself with the same success in every trial.

Many were indisposed against Bletonism because they looked upon the facts on which it is founded as inexplicable. But M. Thouvenel assigns principles upon which the impressions made by subterraneous waters and mines may be naturally enough accounted for. Having ascertained a general law by which subterraneous electricity exerts an influence upon the bodies of certain individuals eminently susceptible of that influence, and shown that this law is the same whether the electrical action arises from currents of warm or cold water, from currents of humid air, from coal or metallic mines, from sulphur, and so on, he observes, that there is a diversity in the physical and organic impressions which are produced by this electrical action, according as it proceeds from different fossil bodies which are more or less conductors of electrical emanations. There are also artificial processes, which concur in leading us to distinguish the different focuses or conductors of mineral electricity; and in these processes the use of electrometrical rods deserves the attention of philosophers, who might perhaps in process of time substitute in their place a more perfect instrument. Their physical and spontaneous mobility, and its electrical cause, are demonstrated by indisputable experiments.

On the other hand, our author proves, by very plausible arguments, the influence of subterraneous electrical currents, compares them with the electrical currents of the atmosphere, points out the different impressions they produce according to the number and quality of the bodies which act, and the diversity of those which are acted upon. The ordinary sources of cold water make impressions proportional to their volume, the velocity of their currents, and other circumstances. Their stagnation destroys every species of electrical influence; at least, in this state they have none that is perceptible. Their depth is indicated by geometrical processes, founded upon the motion and divergence of the electrical rays; but there are second causes which sometimes diversify these indications, and occasion seeming errors. These errors, however, according to our author, are only exceptions to the general rule; exceptions which depend on the difference of mediums and situations, and not on the inconstancy or insufficiency of the organic, sensitive, or convulsive faculties of the Bletonite.

All the hot springs in France, traced by our author from the places where they flow to the places where their formation commences (sometimes at a distance of 15 leagues), led him constantly to masses of coal; where they are collected and heated in basins of different depths and dimensions, nourished by the filtration of lakes and the course of torrents, and mineralized by saline, sulphureous, metallic, and bituminous substances, in the natural furnaces where they are heated, or in the strata through which they flow.

The last and most singular and important phenomenon which our author met with in the course of his experiments must not be here omitted. Over the veins of iron mines alone the electrometrical rods assume a motion of rotation diametrically opposite to that which they exhibit over all other mines. This phenomenon takes place with the same distinction when iron and other metals are extracted from their mines and deposited under ground. But the most remarkable circumstance in this distinctive action of these metals is, that it has a uniform and constant direction from east to west in all metals, iron excepted, just as iron rendered magnetic has an action directed from south to north. The action of red metals is more palpable than that of the white; but the latter, though weaker, has nevertheless a real existence in the sulphur.

In the supplement to this memoir, there is an accurate account of the processes that have furnished these invariable results. They will naturally suggest, says our author, the idea of constructing an electrical compass, which may be of as eminent use in experimental philosophy as the magnetic compass is in navigation. The natural and spontaneous direction of metallic emanations towards the west being ascertained, it only remains to render them palpable by the construction of an instrument which may be substituted in the place of Bletonism, the electrometrical twig that goes vulgarly by the name of the divining rod.

His analysis of the hot springs of Bourbon-Lancy, to the source of which in the great mountains of Burgundy he was led by the electrical sensations of Bleton, shows the great intelligence and sagacity of our author in operations of this nature. He found the origin of these famous hot springs in the centre of an oblong rising ground, full of coal, and commanded on three sides by a group of mountains, of which the greatest part was filled with the same mineral. From a particular case, here circumstantially described, in which the electrical rays of the subterraneous water and those of the adjacent coal crossed each other, our author deduces a very natural account of the errors which may sometimes, though rarely, mislead for a time the greatest adepts in Bletonism, when they find themselves in combined spheres of electrical activity. Another observation, which seems confirmed by several facts, accounts farther for this fallibility: the observation is, that electrical rays, whether direct or collateral, issuing from subterranean focuses, seem to undergo in certain cases a sort of refraction as they pass from one medium to another, or traverse bodies which differ with respect to the property of transmitting this electricity. In a word, it follows from these observations, that when such privileged investigators of currents or minerals as Bleton are placed upon the electrical spheres of these bodies, they will indicate their situation and their respective depths according to the impressions they feel within themselves, or the motions they observe in the electrometrical instruments which they employ; and if they meet with second accidental causes or complications of electrical spheres, which modify or alter these methods of trial, this will necessarily occasion mistakes in the results of their operations which they may probably rectify; but which, at all events, it would be unjust to lay to their charge, or allege as an objection against the reality of their talent.