Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . g and suspendingthe action of the engine when the telegraph beginsand ceases to work. 326. The deflection of the gold leaf galvanoseope, RECIPROCATING ARMATURE ENGINE. 205 (Fig. 63), has recently been proposed as a means oftelegraphic indication. The extreme delicacy of thisinstrument enables it to give a result with a singlepair of plates through great lengths of wire. Thereare no means, however, of recording its action,which would also be seriously
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . g and suspendingthe action of the engine when the telegraph beginsand ceases to work. 326. The deflection of the gold leaf galvanoseope, RECIPROCATING ARMATURE ENGINE. 205 (Fig. 63), has recently been proposed as a means oftelegraphic indication. The extreme delicacy of thisinstrument enables it to give a result with a singlepair of plates through great lengths of wire. Thereare no means, however, of recording its action,which would also be seriously interfered with bythe influence of atmospheric electricity on the con-ducting wire. The transmission of the battery cur-rent through the telegraphic wire, however long, ispractically instantaneous. Experiments which havebeen made on the velocity of electricity, appear toindicate that it is considerably greater than thatof light, which travels nearly 200,000 miles in asecond of time. 327. Reciprocating Armature Engine. — In thisinstrument, contrived by Dr. Page, two electro-mag-nets of the U form, represented at M M (Fig. 140), Fig. are firmly secured in a vertical position, the fourpoles appearing just above a small wooden two armatures, A A, connected by a brass bar, 206 D A VI S S MANU A L. move upon a horizontal axis in such a manner thatwhile one is approaching the poles of the magnetover which it is placed, the other is receding fromthose of the other magnet. The brass bar is con-nected with one extremity of a horizontal beam, th?other end of which communicates motion by meansof a crank to a fly-wheel. On the axis of the fly-wheel at B is the break-piece. Each magnet beingcharged in succession, the armatures are attractedalternately, communicating a rapid reciprocating mo-tion to the beam, and consequently a rotatory oneto the fly-wheel. 328. Horizontal Reciprocating Engine.—Twoelectro-magnets of the U form, M M (Fig. 141), are Fig. 141.
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
