The right side lock ignites the bullseye lantern to illuminate the threat, the left lock fires a ball at the illuminatee.
The problem with that theory is that the right-side pan doesn't communicate with the lamp.
I dunno as a 17th/18th century home defense i think it would be perectly useableI suspect that we're too focused on FUNCTIONAL art such as we own and shoot to appreciate the "steampunk" artsy aspect of this thing. It's pretty obviously not intended as a useable item which is why so many of us are tilting our heads slightly to one side and uttering a confused "huh?..... "