. Operation of trains and station work and telegraphy . osed, 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 sc
. Operation of trains and station work and telegraphy . osed, 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 separatedfrom the base of the key by a non-conducting materialwhich insulates it from the frame, so the current cannotpass through, except when the lever is down or thecircuit closer under the lip. On the top and in the. Fig. 4. center of this is inserted a small piece of platinum;above this on the under side of the metallic lever isanother piece of platinum. The spring is arranged toseparate the two platinum points, thus opening the cir-jcuit. A metallic arm or circuit closer is attached tothe base of the key near the second leg, so arrangedthat it can slide under the lip directly connected withthe first leg thus closing the circuit when the key isnot in use. To prevent the operator from receiving anelectrical shock the finger pieces of both the level andthe circuit closer are of non-conducting material. TELEGRAPHY 27 THE RELAY. The chief use of the relay is to resist all over-produc-tion of current. It has its connections with both mainline and local circuits. It consists of an electro-magnethorizontally arranged upon wood and metallic base; thesmall magnet wires go through the base and connectdirectly with the main line binding posts. In front
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadtrains, booky
