Bones of the Ear
A, the malleus, or mallet, with its long handle running down, to touch with its delicate extremity the membrane of the drum. B, is the incus, or anvil, nicely fitted to the mallet, and showing C, the orbicular bone placed between its termination, and D, the stirrup. The line a,b, represents the center of motion of the malleus, and c,d, the center of motion of the incus. Now this chain of bones acts on the principle of a long level, as a small motion at one end of a long pole serve to move it through a wide space at the other.