Magnetism may be produced in any bar of steel, either by rubbing it with a loadstone, or by placing it in a certain position in relation to the magnetic currents of the earth, and, by a blow or any other means, disturbing its molecular arrangement. This principle appears to involve the iron as with an atmosphere, and to interpenetrate it. By one magnet we may induce magnetism in any number of iron bars without its losing any of its original force. As we have observed of the electrical forces already considered, the magnet constantly presents two points in which there is a difference manifested by the circumstance that they are always drawn with considerable power towards the north or south poles of the earth. That this power is of the same character as the electricity which we have been considering, is now most satisfactorily proved. By involving a bar of soft iron which, being without any magnetic power, is incapable of sustaining even an ounce weight, with a coil of copper wire, through which a galvanic current is passing, the bar will receive, by induction from the current, an enormous accession of power, and will, so long as the current flows around it, sustain many hundred pounds weight, which, the moment the current is checked, fall away from it in obedience to the law of gravity. Thus the mere flow of this invisible agent around a mass of metal possessing no magneto-attractive power, at once imparts this life-like influence to it, and as long as the current is maintained, the iron is endowed with this surprising energy. This discovery, which we owe to the genius of Oersted, and which has, indeed, given rise to a new science, electro-magnetism, may be regarded as one of the most important additions made to our knowledge. Current electricity is magnetic; iron is not necessary to the production of magnetic phenomena, although by its presence we secure a greater amount of power. The copper wires which complete the circuit of a galvanic battery, will attract and hold up large quantities of iron filings, and the wires of the electric telegraph will do the same, while any signal is being conveyed along them. Again, all the phenomena common to galvanic electricity can be produced by merely disturbing the power permanently secured in the ordinary magnet. It was thought that magnets would become weakened by this constant disturbance of their magnetism; but, since its application to the purpose of manufacture, and magneto-electricity has been employed in electro-plating, it has been found that continued action for many years, during which enormous quantities of electricity have been thus given out and employed in producing chemical decomposition, has not, in the slightest degree, altered their powers. Thus a small bar of metal is shown to be capable of pouring out, for any number of years, the principle upon which the phenomena of magnetism depend.