Laxey of the Isle of Man, was built in 1854 to pump water from the Laxey mine shafts. Now a tourist attraction, it remains the largest working waterwheel in the world. Designed by Robert Casement, it is in diameter and wide. It revolves at about 3 rpm. The mines employed over 600 miners at their peak, producing lead, copper, silver and zinc, until they closed in 1929. The Wheel was owned by Edwin Kneale from 1939 to 1965; he saved it from being dismantled and ran it as a tourist attraction, before passing it on to the Manx nation, with the
Largest known prime number Largest known prime number The largest known prime number () is 2 − 1, a number with 23,249,425 digits. It was found by the Great Internet Mersenne Prime Search (GIMPS) in 2017. Euclid proved that there is no largest prime number, and many mathematicians and hobbyists continue to search for large prime numbers. Many of the largest known primes are Mersenne primes. , the seven largest known primes are Mersenne primes. The last sixteen record primes were Mersenne primes. The fast Fourier transform implementation of the Lucas–Lehmer primality test for Mersenne numbers is fast compared to other known primality tests