Later in the game you'll hear the Balloon theme playing as you tour the world in the balloon. The tune is a bit repetitive, and due to the semi-uncontrollable nature of the balloon, you'll hear the tune many times over. Though a rather ineffective means of travel, the balloon is necessary to reach certain parts of Britannia.
The tune has a rather odd volume fluctuation as it repeats every 14 seconds. The change in volume it minor, but enough to be noticed by the trained ear. The reason for this fluctuation is unknown. It may have been included to make the tune more interesting, it may have been an artifact of working with the NES audio chip, it may be a bug in the song, or it may just be a problem with the NSF player.
Balloon is an unofficial name. It is track 17 in the NSF file.