1929: UK - Frank Whittle, combining the concepts of rocket propulsion and gas turbines, invented jet propulsion. Independently, Hans von Ohain put together the same combination in 1933
1929: UK - Great Depression (to 1932), British segment hits worst in 1931, when unemployment surges quickly to more than 3.25 million in 1931, then more slowly to a high of 3.75 million in September 1932
1701 - 1750 (~ 49 years)