The circuit closing lever should make contact with a small strip of spring brass under the lower contact point so that the contact is connected to the frame of the key through the circuit closing lever when the latter is "closed".
The adjustment screw on the key frame is used to regulate the upward stroke of the key lever.
The adjustment screw on the key lever is used to regulate the spring tension of the lever. The lower end rests against the top of a small spiral spring made of brass wire.
[Illustration: FIG. 91.—American Morse Code.]
Connecting the outfit is a very simple mater. The two inside terminals of the sounder magnets should be connected together. One of the outside terminals is led to a binding post mounted on the back of the base. The other terminal is connected to the lower key contact. The frame of the key is connected to a second binding post at the back of the base. The connecting wires should pass through small holes and along the under side of the base.
The Morse Telegraph Code is shown in Figure 91.
A single dry cell will provide sufficient current for practising the Code. The cell should be connected to the two binding posts and the circuit closing lever should be kept open at all times or the battery will become exhausted.
[Illustration: FIG. 92.—Circuit for Two Instruments.]
The number of batteries required on a long line will depend upon the resistance of the line and cannot easily be pre-determined.
Figure 92 shows a circuit for connecting two instruments on a line. When the double contact switch is on point A the batteries are out of circuit. Throwing the switch on B puts the batteries into circuit. They should be kept out of circuit when the stations are not in use. The circuit closer at Station 1 must be kept closed when Station 2 is telegraphing and vice versa.