. Operation of trains and station work and telegraphy . ssupposed to travel in circles or lines around bodieswhich it may traverse. Thus it was discovered if apiece of steel or hard iron be encircled by fine insulatedwire and an electric current applied to the wire the ironwould become magnetized and remain a magnet, ashard iron or steel when once magnetized wTill retain itsmagnetism for a long time; therefore soft cores of ironare always used for electro magnets as soft iron can be imagnetized and demagnetized several thousand times asecond. TELEGRAPHY 25 ELECTRO-MAGNET. The Electro-Magnet co
. Operation of trains and station work and telegraphy . ssupposed to travel in circles or lines around bodieswhich it may traverse. Thus it was discovered if apiece of steel or hard iron be encircled by fine insulatedwire and an electric current applied to the wire the ironwould become magnetized and remain a magnet, ashard iron or steel when once magnetized wTill retain itsmagnetism for a long time; therefore soft cores of ironare always used for electro magnets as soft iron can be imagnetized and demagnetized several thousand times asecond. TELEGRAPHY 25 ELECTRO-MAGNET. The Electro-Magnet consists of two cores of softiron about the size of an ordinary lead pencil, uponwhich is wound a great many feet of fine insulatedcopper wire, each core being wound in the same directionand covered with a casing of polished, vulcanized rubberhaving heads of the same material, thus making spoolsof each; and screwed to a flat connecting bar known asthe heel piece; both inside ends of the wires are con-nected together, and the outside ends of the wire are. Fig. 3. connected together and the outside ends connected tothe instrument binding posts to receive the wires whichconduct the current. When the circuit is closed, thecurrent by passing through the turns of the wire calledthe helix of the magnet causes the soft cores of ironto become magnetized, possessing the power of attract-ing with considerable force any piece of iron broughtnear the ends and ceasing when the circuit is open. THE KEY. The principal use of the key is to open and close thetircuit to produce the dots and dashes. It is a mechani-cal device manipulated by hand to transmit telegraph 26 TELEGRAPHY signals. It consists principally of a metallic lever upona trunnion supported by screws on the elevated sides ofa metallic base. Beneath the base are two metallic legswhich extend through the table; these legs hold thekey firmly to the table and connect with the two ends ofthe main line wire. The front leg and lip is separ
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadtrains, booky
