same. Contact was not found to be necessary, for the effect was instantaneously produced by mere juxtaposition, though thick glass intervened; and filings arranged themselves in right lines across the wire, on a glass plate held over it at the distance of a quarter of an inch. The effect was proportional to the quantity of electricity passing through a given space, without any relation to the metal transmitting it. Increasing the size of the plates, proportionally increased the magnetic effects of the connecting wires. The wire connecting a battery of sixty pairs of plates, did not take up half so much filings as when the battery was arranged so as to form thirty pairs of plates of twice the size. The magnetic powers of the wire invariably rose with its heat. Considering that a great quantity of electricity was necessary to produce sensible magnetism, Sir H. Davy concluded that a current from the common machine would have no effect, while a discharge would; and this he found to be true, the poles of the needle magnetized being situated exactly as before. In these experiments, a battery of seventeen square feet, being discharged through a silver wire, onetwentieth of an inch in diameter, rendered bars of steel two inches long, and from one-tenth to one-twentieth of an inch in thickness, so powerfully magnetic as to lift up pieces of steel-wire and needles, and even to communicate the effect to needles at the distance of five inches from the wire, though water, or thick plates of glass or metal, intervened. By these kinds of experiments it was also found, that a tube, one-fourth of an inch in diameter, and filled with sulphuric acid, did

not conduct electricity enough to render steel magnetic; that an explosion through air made the needle transversely to it magnetic, though not so strongly as a wire would have done; that steel bars in the circuit, or parallel to it, did not become magnetic; and that two bars placed together across the wire passing through the common centre of gravity, shewed no magnetism after the discharge and before they were separated, but exhibited opposite poles on separation. From all which, Sir H. concludes, that magnetism is produced whenever concentrated electricity is passed through space.

On arranging numerous wires in circles, and other directions round the discharging wire, it was found after the discharge that all were magnetic, and the poles exactly as before expressed, the north pole of one needle being towards the south pole of the next, and in a constant relation to the course of the discharge. The connecting wire being divided by small wires, into three, four, or more parts, and the voltaic battery discharged through them, they were all found to have become magnetic, and took up separate cylinders of filings, the opposite sides of two of which, when brought together, attracted each other. From this it was expected, that, when the similar sides were brought together, the filings on them would attract each other. This was accordingly tried by two batteries arranged parallel, but in opposite directions. The filings on these connecting wires repelled each other, and connecting wires of platinum and fine steel without filings exhibited similar phenomena of attraction and repulsion. On placing straight pieces of platinum, silver, and copper-wire, on

two knife-edges of platinum connected with the opposite poles of a battery, they were found to be attracted and repelled in directions similar to those already indicated. Sir H. has likewise pointed out a very simple method of making magnets, viz. by fixing bars of steel across, or circular pieces of steel fitted for horse-shoe magnets round, the electrical conductors of buildings, and exposed situations.

The last individual whose labours in this newly-explored region of science we shall notice at present, is Mr Fara day, of the Royal Institution. His attention was first directed to the verification of the results obtained by preceding inquirers as to the attractions and repulsions of the needle by a connecting wire; but in attempting this, he ascertained that the position of the needle with respect to the wire greatly modified the effects produced; that the apparent attraction of the needle on one side, and consequent repulsion on the other, did not occur under all circumstances; but that according as the wire was placed nearer to, or farther from, the pivot of the needle, attraction or repulsion was produced on the same side of the wire. Hence he concludes, that the centre of magnetic action, or the true pole of the needle, is not placed at its extremity, but in its axis at a little distance from its extremity and towards the middle; that this point has a tendency to revolve round the wire, and the wire round the point; and that, as the same effects in the opposite direction take place with the other pole, each pole has the power of acting on the wire by itself, and not as any part of the needle, or as connected with the opposite pole. The attractions and repulsions he considers merely as exhibitions of the revolving motion in different parts of the circle. Our limits will not permit us to describe the numerous and interesting experiments of Mr Faraday with the poles

and wires arranged in different ways, nor to enter upon the consideration of the facts which he has brought forward to determine the influence of terrestrial magnetism in producing the effects obtained by a common magnet. From his experiments, however, he has deduced the cause of the direction taken by M. Ampere's curve, which he considers a polygon of an infinite number of sides, shewing, at the same time, that the attempt of those sides to rotate by terrestrial magnetism, would place the curve in the position which M: Ampere found it to take in his experiments. Mr Faraday concludes this part of the subject by stating his expectation, "That in every part of the terrestrial globe, an electro-magnetic wire, if left to the free action of terrestrial magnetism, will move in a plane (for so the small part we can experiment on may be considered) perpendicular to the dip of the needle, and in a direction perpendicular to the current of electricity passing through it." In consequence of this law an expectation was entertained, that where the dip was small, a difference in the weight of an electro-magnetic wire might be perceived when the current passed through it in different directions. In endeavouring to determine whether, in these latitudes, the difference was perceptible, a very remarkable effect was observed. A piece of wire being suspended from a lever, and very fine wires let dip from it into two cups of mercury, it became apparently lighter every time the electrical current was passed through it either the one way or the other; but this effect was at last found to be, not a real alteration in the weight of the wire, but an affection of the mercury with which it was in contact. Hence it was concluded, that when electricity passes from a fine wire into mercury, or from mercury into a fine wire, an effect is produced equivalent to a diminution of the cohesive attrac

tion of the mercury. Whether such a diminution really takes place, or the effect in question is to be ascribed to some other cause, remains to be determined by further experiments.

We reserve the full account of M. Ampere's theory of electrical currents, for the scientific chapter of our succeeding volume. The outline above given, will, however, afford our readers a pretty correct notion of the zeal and success with which the career of discovery in this interesting branch of science, so happily opened by M. Oersted, has been prosecuted by the expe

rimental philosophers both of England and France. Taking the phenomena of the polarization of light, in conjunction with the discovery of the identity of the chemical and electrical powers, to which our attention has just been directed, it seems no longer doubtful that light, magnetism, and electricity, are only different modifications of one substance, and that the general law, by which their apparently incompatible phenomena shall be reconciled and explained, will, at no great distance of time, be evolved.

UNDER this head, the foremost place in this department inust, indisputably, be assigned to the expedition returned from the northern seas, and from discoveries made, as it were, beyond the boundaries of nature herself. An almost unprecedented interest had been excited relative to this voyage, both in the public, and among all the circles of science. The daring career with which the expedition had rushed into the depth of the frozen regions, the mysterious manner in which it had disappeared, and been, as it were, buried among them; its sudden re-appearance, after hope had almost expired, gave to its narrative all the interest of romance. Science and navigation looked to it for the solution of some of their most interesting problems, and for the examination of nature, under an aspect which she never presented, unless to those daring mortals, who thus thrust themselves into her most awful recesses.

A decided scepticism had prevailed

at the Admiralty, and in other naval circles, as to Lancaster Sound being a bay enclosed by land, the belief of which had induced Captain Ross to return without exploring that inlet. Lieutenant, now Captain Parry, being also of this opinion, and entertaining confident hopes of finding it a passage into the Arctic ocean, was selected for the conduct of a new expedition. In fitting this out, nothing was omitted which could render it efficient for so arduous an object.

Two vessels were prepared, one called the Hecla, of 375 tons, built originally for a bomb vessel, and carrying a company of fifty-eight persons; the other, called the Griper, a twelve gun brig of 180 tons, with a crew of thirty-six men. The first was commanded by Captain Parry himself; the other, by Lieutenant Liddon. Both had the whole of their outside covered with an extra lining of oak plank, and their bows defended by strong plates of iron. A large

stock of coals was lodged as ballast, and every care was taken to supply the crew with warm clothes and fresh provisions.

The expedition, thus equipped, and furnished with every kind of scientific instruments, set sail from Deptford on the 4th May, 1819. On the 4th July, they were nearly in the latitude of Lancaster Sound, but on the opposite side of Baffin's Bay, the whole centre of which consisted of one unbroken mass of ice. Unwilling to lose time by making a circuit of the bay, as on the former voyage, Captain Parry determined upon an effort to work his way across this barrier. Accordingly, the crews set to work, warping and heaving their way between the floes; but the obstacles were so great, that they were obliged, in many cases, to saw their way through the ice, an operation never before attempted. By these efforts, and by the aid of a strong easterly wind, they forced their way across in the course of six days. On the 2d of August, they found themselves at the mouth of Lancaster Sound; and had the gratification of noticing, that this was a month earlier than in 1818, though they had sailed a fortnight later.

On the 3d, the expedition entered the Sound; and on the 4th, they had completely passed that mountain barrier, which, under the influence of visual deception, had been supposed to bar all farther passage. An extraordinary exultation was felt at overcoming this obstacle, and at entering into a depth of unknown seas, where every hour's sail would be a discovery, and where, from the early season of the year, they might hope to effect much. The rocks here were particularly rugged and precipitous, resembling immense walls in ruin.

On leaving Lancaster Sound, the ships entered Barrow's Strait, which

seems to be with difficulty distinguished, its channel being merely a continuation of the other. After advancing a certain space, however, to where the left side was diversified by some small islands, to which the name of Prince Leopold was given, they found it completely blocked with ice, and were obliged to seek a passage down a broad inlet, called Prince Regent's inlet; but in a short time they found it also blocked up, and were obliged to return to the first channel. Happily, the ice there was found to be dissolved, and they were able to proceed in a due westerly course. They now passed a succession of islands, making an almost continuous coast on their right; while on the left, or to the south, the open Polar sea extended. At length they came to an island larger than any of the rest, to which they gave the name of Melville Island. On the 4th September, they crossed the meridian of 110°; and Captain Parry was able to announce to the exulting crew, that they had earned the reward attached by government to the attainment of that longitude. They proceeded about three degrees farther west, to Cape Providence; but the ice then set in with such intensity, that it became absolutely necessary to return to a secure harbour, which they had passed, and which, as it behoved them to spend the winter there, they named Winter Harbour. The entrance was now guarded by a field of ice two miles and a quarter broad, which it was necessary to cut through with a saw, and then, with great labour, to float away the fragments. This afforded two days and a half of hard labour to both the crews. Having thus brought the ships into a secure position, they dismantled the whole of the masts except the lower one, deposited the boats, yards, masts, and rigging, in a shade erected for