This is a nice puzzle from Clifford Pickover in the 1996 Discover magazine’s Brain Bogglers.
“Thoth, ancient Egyptian god of wisdom and learning, has abducted Ahmes, a famous Egyptian scribe, in order to assess his intellectual prowess. Thoth places Ahmes before a large funnel set in the ground. It has a circular opening 1,000 feet in diameter, and its walls are quite slippery. If Ahmes attempts to enter the funnel, he will slip down the wall. At the bottom of the funnel is a sleep-inducing liquid that will instantly put Ahmes to sleep for eight hours if he touches it.
As shown in the illustration, there are two ankh-shaped towers. One stands on a cylindrical platform in the center of the funnel. The platform’s surface is at ground level. The distance from the platform’s surface to the liquid is 500 feet. The other ankh tower is on land, at the edge of the funnel.
Thoth hands Ahmes two objects: a rope 1,006.28 feet in length and the skull of a chicken. Thoth says to Ahmes, ‘If you are able to get to the central tower and touch it, we will live in harmony for the next millennium. If not, I will detain you for further testing. Please note that with each passing hour, I will decrease the rope’s length by a foot.’
How can Ahmes reach the central ankh tower and touch it? ”
See the Thoth Maneuver