graceful abuses of mathematics. Many mystics of our own day are, however, so partial to mysteries, that the generation must, I fear, be changed before our understandings cease to be offended with the subtle spirits of Albertus Magnus, and Paracelsus.

It is high time, too, that in all cases we regard electrical action as existing only in electrics; and as re-acted upon and stopt by the surfaces so incongruously called conductors. These set bounds to a disturbed stratum, and extend or spread the effect only because, if perfect, they partake of none of the action.

Under the delusion of these radical mistakes, it is really surprising that we have blundered into so many amusing results; but I venture to say that if pride will permit us to reason rightly, all the mysteries and freaks of electricity will be understood and practically applied in a few years to many important and unsuspected purposes.

Mistakes about the agents and their nature have prevented our discriminating what results from different re-agents. These are different in machine, voltaic, and magnetic excitements, and the results necessarily correspond with the structure of each. We do not get showy displays from Voltaism generated in interstices of an inch, and refined and exhibited as it is by the difference between two conductors; and we get even less in the diminutive excitements promoted by the scaly structure of iron. The principle is the same, but the re-agents afford different results; and, perhaps, the same principle operates in as a great variety as there are sets of re-agents.

The similarity is evident in the polar character of each, and that the action is in the space without the miscalled conductors is evident from the inductive action of each; while it is palpable that the induction accords with the display, and hence a magnet acts only on iron, because similarity of excitement permits only similarity of action, for which iron by structure alone is adapted.

This theory is what I have laboured to inculcate for at least forty years; and if I am desirous of reiterating it now, it is because I heard all the authorities at Bristol declare publicly that the new facts could not be explained by any of the established theories. Of course it is a subject on which I might enlarge, might adduce proofs, answer objections, &c.; but truth will prevail, and those who are practised in these sciences will readily confer fulness on my brevity.

The analogy between the inductive powers of voltaic wires to produce magnetism, and of terrestrial electricity to produce directive polarity, is the finest idea of this age, if it can

be maintained. It well accords with the friction and pressure of the earth's two motions, so calculated to generate universal electrical action; but the dip demands that the currents should be at great depths, and this and some other anomalies require to be reconciled. I have some doubts, but I wish it success for its magnificence.

R. P.

P. S.-To Mr. Sturgeon.-I have just received a letter from Mr. Crosse, of the date of November 30th, in which it appears that the late hurricane has destroyed thirty-five of those fine trees which adorn his grounds; one of them a beech, containing nine tons of timber, 100 feet high, and spreading over 550 square yards. He reports that he is busily engaged in an infinity of new arrangements; but he states that experimentalists have mighty difficulties to grapple with, though the most important results will, sooner or later, be brought to light. In the first place, he observes, we want a good analysis of the voltaic battery, with a proper discrimination between its intensity and density, so as to determine the cause of simple electric action, the decomposition of fluids, and the fusion of metals; and an explanation of its union. with magnetism, light, heat, &c. comprehending the different qualities in each of the solar rays. We next want a correct account of the natural electric action and re-action of simple and compound substances, beginning with one that is positive to every other, and ending with one that is negative to every other. If, says Mr. Crosse, an experimentalist could be armed with a tolerable share of this knowledge, he might be expected, pretty quickly, to bring to light many results worth knowing.

In reply to some suggestions of mine about the possibility of obtaining a permanent light and heat for all domestic purposes, by voltaic action, without the use or consumption of any combustible substance, he observes that he does not think it absolutely impossible; but that, in the present state of the science, it would be difficult to point out a mode.

R. P.

XXVII. A Description of a Magnetic Electrical Machine, invented by E. M. CLARKE, Magnetician, of 11, Lowther Arcade, Strand.

This apparatus, with the exception of there being rotating armatures and a magnetic battery, differs from any magnetic machine which bas hitherto been constructed.

No. 2, January, 1837.

L

The October number of the Philosophical Magazine for 1836 contains a brief account of this machine; it being the intention of the inventor to reserve a more detailed description for insertion in the "Annals," in consequence of its being the aim of the Editor of the latter named periodicals to make this deservedly interesting branch of science one of the leading features of the work. Since that time, a most important improvement has been made, by the rejection of the mercury box. By the inventor's present arrangement, the necessity of using mercury is superseded.

A, is the battery of bent bar magnets, placed vertically and resting against four adjusting screws, which pass through the mahogany back board B (two of them are shown at M, N.

fig. 12, page 155), C is a bar of stout brass, having an opening in the middle, through which passes a bolt with a screw-wheel, the purpose of which is to draw the magnetic battery to the board B. By these means, the battery can readily be disengaged from the machine, without taking asunder the entire apparatus, and the battery is thus also freed from that vibration which must necessarily be occasioned by the attachment of the rotating apparatus to the battery itself. D is the intensity armature, which screws into a brass mandril seated between the poles of the battery A; motion being communicated to it by the multiplying wheel E. This armature has two coils of fine insulated copper wire, 1500 yards long, coiled on its cylinders, the commencement of each coil being soldered to the armature D, from which projects a brass stem, (also soldered into D), which carries the break-pieces, H and H. The breakpiece is made fast in what position soever is required, by a small binding screw. I and I a hollow brass cylinder, to which the terminations of the coils F G are soldered, being insulated by a piece of hard wood attached to the brass stem. O is an iron wire spring, pressing against the hollow cylinder I at one end, and held in metallic contact by a nurled head-screw in the brass strap M, which is fixed to the side of the wooden block L. P and P a square brass pillar, fitting into a square opening in the other brass strap N, and secured at any convenient height required. Q and Q, a metal spring that rubs gently on the break-piece H, and held in perfect metallic contact by the nurled head screw in P. T and T a piece of copper wire for connecting the two brass straps, M, N; then D, H, Q, P, N are in connexion with the commencements of each coil, and I, O, M with the terminations. The advantages of this arrangement must be obvious to any person who has seen the magnetic machine in action in the Adelaide Gallery of Practical Science, where the old arrangement of the mercury flood is still used, where both disc and blades scatter the mercury about as in fig. 1': a the disc, b, the double blades, c, the mercury flood. The loss of mercury is not the only evil; for as you continue working the machine, you of course lose the adjustment you had at starting, and the effect is constantly diminishing, and will at length cease, owing to the points b not having mercury to dip in. By the new arrangement, the metal spring Q presses gently on the break H; consequently, the effects here are unbroken, no matter how long you

FIG. I.

may require to keep the machine acting. This is not the only advantage it possesses; for in the mercury the surface is very rapidly oxidated; the oxide adheres to both disc and point, and preventing so perfect a metallic contact as that obtained by the spring and break.

To adjust the intensity armature.

See that the faces of the iron cylinders that carry the coils F, G, are parallel to, and all but in contact with, the magnetic battery, A; if not, unscrew the nut of the multiplying wheel E, and take it off its axis: you then have at your command the four screws against which the battery rests, (two of which are to be seen at M N, fig. 12, page 155); by means of them and the nut of the strap C, you can adjust the battery to the greatest nicety. The next step is to adjust the break, so that the spring Q will separate from it just at the same time that the iron cylinders of the armature have left the poles of the magnetic battery; and lastly, see that the iron wire spring O, presses gently against the hollow brass cylinder I.

To give the shock.

Grasp the two brass conductors, R S, in the hands,* put one of their connecting wires into the holes of either of the brass slips, M or N, the other wire into the hole at the end of the brass stem that carries the break, H. Connect M N by T, turn the multiplying wheel in the direction of the arrow, and a violent shock will be received by the person holding R S. The shock which is obtained from the intensity armature having 1500 yards of fine insulated wire, is such that a person, even of the strongest nerves, will not readily volunteer to receive a second shock. Indeed the effects are so violent, that the inventor has proposed to many of his military customers that this instrument would be a good substitute for the lash, being capable of producing even greater torture than that brutal instrument, without producing any corporeal injury to the delinquent. Place RS in two separate basins of salt and water, immerse a hand in each basin, and the shock will also be felt very powerfully; this method is to be preferred, as it leaves the person who is electrified the power of quitting when he pleases; not so with the conductors; for the muscles of the arms contract violently, so as to close the hands

If the hands are wetted with vinegar or salt and water, the effect is considerably increased.