This is an example of one of the bearings used throughout the drive train of the mill. A rotating shaft fits through the hole in the middle of the bearing, the hole being lined with 'babbit metal' (look it up in wikipedia). at the top of the bearing is a small resevoir usually filled with lubricant. The lube is transported into the bearing through the hole in the center by a wick made of carded wool wrapped in copper wire. According to the miller, who made these wicks, the wick has to be inserted such that the flow is in the same direction as the growth of the wool fibers, or the lube doesn't flow!