As Velocette indicates, "Canon a rubans" (French) is what we would call a Danascus barrel. I am sure no one would consider firing that gun, but if so, please don't! The gun is definitely French, probably from about 1840-1850.
It is an interesting gun and I admit having trouble figuring out its "raison d'etre". At .70 caliber, it is much larger than any pocket pistol normally used for personal defense. Pistols are not usually used for hunting, but perhaps it was intended as a "backup" gun for a big game hunter or for stalking wild boar. One thing for sure; it was apparently made for use at close range and would have been devastating at that distance.
It is a pretty gun and the clean and uncluttered engraving gives it a very classy appearance.