A Slotted Anchor
The floor was cooler near the low wall vent. I waited until the faint air ceased its hum. Beside me lay the brass washer and the wire-bound hook. With both paws, I nudged the heavy disc upright against the metal grating. It slid into a narrow vertical slot. Held firm. I took the hook and looped the hooked steel end through the washer's hollow center. A steady tug. No rattle. Anchored. Now... the line can stretch across without slipping.