A line continuously approached by a curve, but which the curve, owing to its construction or nature of curvature, can never touch, be tangent to, or intersect.

A combination of two magnetic needles so adjusted as to have as slight directive tendency as possible. Such a pair of needles when poised or suspended will hardly tend to turn more to one point of the compass than another. The combination is generally made up of two needles arranged one above the other, with [...]

Having no magnetic directive tendency due to the earth’s magnetism. Examples are given under Astatic Needle; Circuit, Astatic; and Galvanometer Astatic.

Speech involving the sounds of words. It is a definition which has acquired importance in the Bell telephone litigations, one contention, concerning the Bell telephone patent, holding that the patentee did not intend his telephone to transmit articulations, but only sound and music.

An arm extending from a rocker of a dynamo or motor, to which arm one of the brushes is attached. (See Rocker.) Ordinarily there are two arms, one for each brush.

The metal covering, often of heavy wire, surrounding a telegraph or electric cable subjected to severe usage, as in submarine cables. Synonym–Armature of Cable.

An armature of a unipolar dynamo. (See Dynamo Unipolar.)

A substitute for bar-armatures in which stranded copper wire conductors are substituted for the solid bar conductors, to avoid Foucault currents. (See Armature, Bar.)

An armature of a dynamo which is wound on a spherical core, so as to be almost a sphere. It is employed in the Thomson-Houston dynamo, being enclosed in a cavity nearly fitting it, formed by the pole pieces.

The original Siemens’ armature, now discarded. The core was long and narrow, and its cross section was nearly of the section of an H. The grooves were wound full of wire, so that the whole formed almost a perfect cylinder, long and narrow comparatively. (See Winding Shuttle.) Synonym–Siemens’ Old Armature–Girder Armature–H Armature.