Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . nd fastened to a small mica disc and rigidlyjoined together by a fine glass rod ; midway between the needles isfastened the mirror, mounted on a mica vane and secured to the glass rod. The micavane assists in damp-ing by fanning the airwhen the needles aredeflected. The wholesystem is suspendedby a cocoon fibre at-tached to the upperend of the glass rodandextendingthroughand protected by thevertical brass the door isclosed the mirror maybe seen through aglass window. Bind-i
Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . nd fastened to a small mica disc and rigidlyjoined together by a fine glass rod ; midway between the needles isfastened the mirror, mounted on a mica vane and secured to the glass rod. The micavane assists in damp-ing by fanning the airwhen the needles aredeflected. The wholesystem is suspendedby a cocoon fibre at-tached to the upperend of the glass rodandextendingthroughand protected by thevertical brass the door isclosed the mirror maybe seen through aglass window. Bind-ing posts are providedfor the terminals ofeach coil and the coilsmay be connected inseries, parallel, etc.,care being exercisedto have the directionof current as given inFig. 167. The coils ofeach needle may beused separately forcomparing two differ-ent current strengthsat the same time,when the direction ofthe current in each issuch as to tend to turnthe mirror so used the instrument is called a differential a special form of mirror reflecting galvanometer called a ballistic. Fig. 168.—Thomson Mirror-Reflecting Double CoilAstatic Galvanometer with Case Open. GALVANOMETERS. 181 galvanometer, used for measuring momentary currents (as inductioncurrents or the discharge of a condenser, fl 803), the magnetic systemis constructed so as to have considerable weight, and arranged togive the least possible damping effect. If a momentary current bepassed through its coils, the impulse given to the needle does notcause appreciable movement of the magnetic system until the currentceases, owing to the inertia of the heavy moving parts, the result
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1901
