public void open()
    {
        try {
            // Only try if we do not already have a sequencer
            if ( sequencer == null ) {
                sequencer = MidiSystem.getSequencer();
            }
            sequencer.open();
        } catch( MidiUnavailableException e) {
            System.err.println("The midi system is unavailable.");
        }
    } // End openMidi