Mysterious Trunk and Mysterious lock

I foudn this chest in my mother's home.WE were looking at it and she got interested in the value. But I don't care about the value. I care about knowing the history. maybe where it came from. And more importantly, what this lock is, i have found a few examples of a "Pat'd April 15 1879" engraved lock jsut like the one in the photos. But no one seems to know the original patent or where this came from. Any help would be appreciated.