ARMATURES OF DYNAMOS

Armature is a French term, meaning armor originally from its Latin deriva-— tion. It is applied to a bar or piece of © soft iron connecting the poles of per-— manent or electric magnets, which are then said to be armed. More specifically, | their shape, such as cylindrical, drum,|N. girdle, or spherical armatures; or from their construction or winding, such as disk, multipolar, polarized, ring, shuttle or unipolar armatures. Applied to a permanent magnet, an armature is also known as a keeper, as it preserves the magnetism when not in use. Thus utilized, the armature itself becomes a magnet with reversed poles, so operating on the particles of the permanent magnet that they remain in a state of active magnetic tension. Horseshoe magnets are never laid aside without their protecting armatures. Straight-bar magnets have two placed parallel with poles reversed; they thus have a keeper or armature sustaining their magnetic force at each end. Armatures are also useful parts of telegraph sounders.