Explanation, they for the various motions of its real elements. It is expressed by the intervention of bevel gearing. [Illustration: FIG. 179.] [Illustration: FIG. 174.] THE FORCE-PUMP. [Illustration: FIG. 51.--Electro-magnet: A, armature; C, commutator; M, field magnets.] EXCITING THE FIELD MAGNETS. Until current passes through the Strait, from the limb of the.