Page:The American Cyclopædia (1879) Volume XV.djvu/640

 612 TELEGRAPH graph were only evanescent. The apparatus was improved by the substitution of a sharp point for the pen or pencil, which is attached to one end of a lever, at the other end of which is the movable armature. The follow- ing illustrations exhibit the several parts of the Morse instrument as now in use. The key, fig. 1, consists of a brass lever L, swung on pivots, and having on one end a button. When this button is pressed down, two pla- tinum wires, a and 5, are brought into contact, thus closing the circuit; when the pressure is removed, a spring lifts the lever, separates the wires, and breaks the circuit. When the message is sent the operator permanently closes FIG. 1. Key. the circuit by springing to the left the lever S, which brings into contact the duplicate pla- tinum wires a' V. The relay magnet, fig. 2, is an electro-magnet wound with a long fine wire, which is introduced into the main line and becomes a part of the great conductor from city to city. When the key breaks and closes the circuit, the relay receives the voltaic a. 6 FIG. 2. Belay. current and becomes magnetized and demag- netized. The delicately poised lever L, having the armature of the magnet attached to it, vibrates forward and backward, bringing to- gether the two platinum wires a 5, and thus breaking and closing a secondary or local cir- cuit, embracing a local battery and a strong electro-magnet. This magnet performs various work, such as embossing or printing paper, or the liberation of machinery for the production of sounds. A screw B is used to move the magnet coils backward and forward so as to adjust the general magnetic power, and a spring S retracts the armature after magnetic attrac- tion has drawn it forward. The sounder, fig. 3, is an electro-magnet used in the local circuit. The armature, A, is attracted by the electro- magnet M, causing the lever L to vibrate be- tween the screws S S, which are so adjusted as to limit the vibrations. The backward and FIG. 8. Sounder. forward blows thus given, some of which are short and some long, correspond to the dots and dashes of the Morse alphabet. This is now more generally used than the Morse regis- ter or recording instrument, as experience has proved that fewer errors are made by the ear than by the eye. The Morse register, fig. 4, has also the electro-magnet M, the armature A, the lever L, and the adjusting screws S S ; but instead of producing sounds merely, the lever L embosses on a fillet of paper P dots and dashes in precise accordance with the move- ments of the key and relay. The paper is car- ried between two rollers, moved by clockwork, in one of which is a groove, into which the steel point presses the paper. When successive blows are struck on the key, closing and open- ing the circuit quickly, corresponding dots ap- pear on the paper ; but if the key be pressed down for a longer or shorter time, keeping the circuit closed, a continuous line of any desired length may be produced on the paper. The signs for the letters of the English alphabet FIG. 4. Register. (which are variously modified to adapt them to other alphabets), and for the numerals and punctuation marks, are as follows, those most used being the simplest :