The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

446 THE MORSE TELEGRAPH APPARATUSES.
TIE MODERN RELAY MAGNET.
The modern relay magnets are of many forms of construction. I will describe one of them in detail. Fig. 33 represents the magnet as it sets upon the table, with its wooden
base, having at each corner binding posts. The line wire
enters the hole in the post A, and is bound by the screw in its
top. To the post A is soldered the copper wire leading to the
spools or coils of the magnet. One end of the insulated wire
that surrounds the coils is joined to the wire that leads to the
post A; the other end of the spool wire is in the same manner
connected with the post M. The current from the line wire
enters the station and follows the conductor to the post A,
thence through the magnet coils, thence to post Mi, and thence
to the battery.
The local circuit is united to the posts B and c; the lower
Fig. 33.
end of post B is connected by a wire beneath the base to the
metallic frame G; the other local post, c, is connected by a
wire underneath to the metallic standard ii; the armature D
is attached to a brass upright lever, on the side of which, near
E, is fixed a piece of platina; K is an adjusting screw, with
an insulating point, F, made of ivory; L is another adjusting
screw, with a platina point E. The upright lever attached to
the armature D does not touch the brass arm H. Suppose a
current is transmitted over the line wire; it traverses the coils
and produces magnetism in the cores of the spools. The armature D is then attracted toward the magnet, and the upright
lever is brought into contact with the platina point E, which
closes the local circuit. The current from the local battery
will then flow with the copper wire conductor to the post B,