Release Message:  Which way does a sprinkler rotate when submerged in a tank and made to suck in the surrounding fluid? Authored by Richard Phillips Feynman.

Description:  Which way does a sprinkler rotate when submerged in a tank and made to suck in the surrounding fluid? also referred to as a Feynman inverse sprinkler or as a reverse sprinkler, is a sprinkler-like device which is submerged in a tank and made to suck in the surrounding fluid. The question of how such a device would turn was the subject of an intense and remarkably long-lived debate. A regular sprinkler has nozzles arranged at angles on a freely rotating wheel such that when water is pumped out of them, the resulting jets cause the wheel to rotate; both a Catherine wheel and the aeolipile ("Hero engine") work on the same principle. A "reverse" or "inverse" sprinkler would operate by aspirating the surrounding fluid instead. The problem is now commonly associated with theoretical physicist Richard Feynman, who mentions it in his popular autobiographical book Surely You're Joking, Mr. Feynman!. The problem did not originate with Feynman, nor did he publish a solution to it.