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

424 THE MORSE TELEGRAPH APPARATUSES.
between them and the roller T T. In fig. 1 will be seen the
key 6, 7, 8, and 9, shown on a large scale by fig. 4. v v is
the platform; S is a metallic anvil, with its smaller end
appearing below, to which is fastened the copper wire c; 7 is
the metallic hammer attached to the brass spring 9, which is
secured to the block 6, and the whole to the platform. The
copper wire d is fastened to the brass spring 9, and the other
end to the line wire; c to b, and a runs to the voltaic battery.
In order to close the circuit between 7 and 8, fig. 4, it was
the custom to place between them a metallic wedge. Suppose
the distant station is communicating to fig. 1, the current
Fig. 2.
would traverse the line, enter by the copper wire d, pass
through the key lever 9, thence through 7 and the wedge
between 7 and 8, thence with the copper wire c united to b,
thence through the magnet coils, thence to a and to the
battery. Such were the original instruments used on the first
line of telegraph constructed in America.
For a long time the mode of making the mark on the paper
was the subject of much study, and it finally resulted in the
abandonment of all inks, and the adoption of the steel point to
indent the paper. The next question of equal solicitude was
the mode of opening and closing the voltaic circuit. The
original port rule system was not satisfactory, and the later