of to rest quickly, differential g

A g. in which there is a double coil of wire surrounding the needle, so that two separate currents can be sent through the coils, in either the same or a contrary direction, intensity g. See tension g. mirror g. See reflecting g. reflecting g. Of Sir William Thomson, a g. in which several short magnetic needles are fastened to a silvered gla mirror, suspended by a silk thread in the midst of a coil of wire. A current pa ing through the wire causes deflection of the needles and hence of the mirror which casts a luminous reflection on a graduated arc. This form of g. gives a very delicate measure of the strength of the current, sine g. Of Pouillet, a g. consisting of a vertical circle, which can be placed in any meridian, and bears a coil of wire. A horizontal graduated circle causes a deflection of the needle through a certain arc, the sine of which is proportional to the strength of the current, string g. A very delicate form of g. in which a minute thread of platinum or silvered quartz is attached between the poles of a strong electromagnet. When a current pa es through the thread the latter suffers a lateral movement, the thread is strongly illuminated and its movements are photographed on a roll of sensitive paper, tangent g. A g. consisting of a very short and thick magnetic needle suspended by a thread so as to occupy the center of a vertical ribbon of wire placed in the magnetic meridian. A current pa ing through the latter causes a deflection of the needle through a certain arc (measured on a horizontal circle), the tangent of which is proportional to the strength of the current, tension g. A g. in which there is a long wire coil; used to measure currents pa ing through circuits of great resistance. Thomson's g. See mirror g. [Galvani + Gr., metron, a measure.]