. The Pharmaceutical era. c field created by the poles of apowerful electro-magnet. The two chief types of armature are the Gramme ringarmature, and the Siemens drum arniature. The Gramme armature consists of an iron ring woundwith insulated wire in such a way that the wire formsan endless coil. (Fig. 103.) The Drum armature is a cylinder of iron wound length-wise with insulated copper wire, also in an endless coil.(Fig. lOi.) Deceniboi- 0. 1807.] THE PHARMACEUTICAL ERA. 873 When either ofthese arniatiiies isturned between tliepoles of a magnet acurrent is set up inone direction in thecoil of
. The Pharmaceutical era. c field created by the poles of apowerful electro-magnet. The two chief types of armature are the Gramme ringarmature, and the Siemens drum arniature. The Gramme armature consists of an iron ring woundwith insulated wire in such a way that the wire formsan endless coil. (Fig. 103.) The Drum armature is a cylinder of iron wound length-wise with insulated copper wire, also in an endless coil.(Fig. lOi.) Deceniboi- 0. 1807.] THE PHARMACEUTICAL ERA. 873 When either ofthese arniatiiies isturned between tliepoles of a magnet acurrent is set up inone direction in thecoil of one side ofthe armature, andanother in the oppo-site direction iu theportions of the coilon the other currents areconducted to metal-lic surfaces on theaxle of the armatureand are here takenofE by means ofpieces of copperknown as brushes,which form the con-nections with theoutside circuit. exhibits appear-ance of finish dyna-mo with drum ar-mature. The electro-mag-net which producesseparately excited by. the armature with the brushes in such a way that wheathe current reverses iu the armature, the commutatoralso reverses its connection with the brushes, so that the+ current always Bows out through one brush and the— current through the other, no matter what the direc-tion may be in the coils. The Electric Motor.—In tlie dynamo the current is pro-duced by causing a conductor to revolve in a magnetic-field, and the development of electric energy is propor-tional to the mechanical energy required to revolve thearmature against the resistance offered by the lines offorce. The dynamo, then, is simply a device for the con-version of mechanical into electrical energy. This proc-ess can also be reversed, for if a current generated byone dynamo is passed in through the brushes of another,the armature of the latter will be caused to revolve, butin a direction opposite to the armature of the machinefrom which the current comes. It is customary, there-fore, to say th
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Keywords: ., bookcentury1800, booksubjectdrugs, booksubjectpharmacy, bookyear1
