In 1759 Euler claimed that there were no closed knight tours on a chess board with 3 rows .
In 1917 Ernest Bergholt found tours on 3 by 10 and 3 by 12 boards .
In 1759 Euler claimed that there were no closed knight tours on a chess board with 3 rows , but in 1917 Ernest Bergholt found tours on 3 by 10 and 3 by 12 boards .