Oh, but it did work. It worked when it was actually practiced from the late 40s to the 70s when the US experiences the highest rates of economic growth in its history. During the 70s the US had about the highest average income levels in its history too (this was briefly matched during the Clinton administration but then incomes fell again).
No, it failed to cure the depression - World War II cured the depression. It was not practiced from the 40's to the 70's. The average family paid 4% in federal taxes in 1950. JFK cut taxes in the early 60's which caused a spurt of economic growth. Reagan cut tax rates (revenues actually INCREASED) in the 80's which again caused a period of growth. We have still not paid the price for FDR (Social Security) and Lyndon Johnson's (Medicare) programs because we have been borrowing money for 30 years. I guess you must think that trillions of dollars of debt is a sign of a good economy.
