| patent log n. Nautical A torpedo-shaped instrument with rotary fins that is dragged from the stern of a vessel to measure the speed or distance traveled. Also called screw log, taffrail log. |
| taffrail log n. See patent log. |
| taffrail log | |
noun | |
| a cigar-shaped log with rotary fins that measure the ship's speed [syn: patent log] |