Galvanized Iron

(Metal.) The great strength of iron has been ingeniously combined with the durability of zinc, in the so-called G. 1., which is made by coating clean iron with melted zinc, thus affording a protection much needed in and around large towns, where the sulphurous and sulphuric acids arising from the combustion of coal, and the acid emanations from various factories, greatly accelerate the corrosion of unprotected iron. (-om'e-tur.) (Elect.) Oersted published in 1819 a discovery which connected magnetism and electricity in a most intimate manner, and became, S a N 6 م + Fig. 341. OERSTED'S EXPERIMENT. in the hands ofAmpère and of Faraday, the source ofe new branch of physics. The fact discovered by Oersted is the directive action which a fixed current exerts at a distance ona magnetic needle. To make this experiment, a copper wire is suspended horizontally in the direction of the magnetic meridian over a movable magnetic needle (Fig. 341). So long as the wire is not traversed, by a current, the needle remains parallel to it; but'as soon as the ends of the wire are respectively connected with the poles of a battery of a single element, the needle is deflected, and tends to take a position which is the more nearly at right angles to the magnetic meridian in proportion as the current is more intense. Ashort time after Oersted's discovery, a German, Mr. Schweigger, invented the G., a very delicate apparatus, by which the existence, direction, and intensity of currents may be determined. It consists of one, and sometimes more, delicate magnetized needles, suspended horizontally by some very slender fibre, and surrounded by a great number of coils of very thin insulated copper wire. When the electric current to be examined is transmitted through the wire, the needle is deflected in a direction, and to an extent, dependent on the direction and intensity of the current. or RHEOSCOPE, (gal-văn'o-skōp.) [s. 393]