Dave;
You misunderstood me. I can plainly see the taper that is like a modern, or vintage, bucket. I thought a firkin tapered the other way, narrower at the top, and wider at the bottom. Wooden butter churns often have this same taper.
My grandmother was raised in the back country of Arkansas and as a girl carried water about a quarter of a mile. They used tin versions of the old wooden firkins to carry water.
Hungry Horse