Fire bucket. From Wikipedia: "A fire bucket is a bucket filled with water or sand which is used to prevent or extinguish fires.Typically, fire buckets are painted bright red and have the word fire stenciled on them. Often they have a convex, protruding bottom. The rounded bottom results in a strong, directed stream of water when the water is thrown at the fire. The rounded-bottom bucket is far more efficient in launching the water at the fire than a flat bottom bucket." A story that has come down to the Mill Museum through its oral histories is that fire buckets had rounded bottoms so that the workers responsible for keeping them filled could not set them on the floor, because they would tip over. This forced the workers to hang the buckets back up on their hooks, where they could be easily found if needed. Date unknown.