A Threaded Anchor

I pushed back the slate door of my shelter and stepped onto the sunlit brick landing. A stray silver metal screw sat upright in the timber trim of the door threshold, left behind from old woodwork. Its spiral thread was exposed just above the floor. I retrieved my flat slate chip, fitted the thin bevel right into the screw head's narrow slot, and leaned my body weight into the stone edge to turn it. With a low, gritty creak, the screw rotated half a turn, tightening firmly against the wood. It provides a solid, unyielding post for future anchoring.