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 Abt 1920 - 1923 (~ 3 years)
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Date |
Event(s) |
| 1 | 1920 | - 1920: The tommy gun patented by John T Thompson.
- 1920: The Band-Aid invented by Earle Dickson
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| 2 | 1921 | - 1921: Warren Harding president of the USA 1921. Warren Harding dies of an embolism in San Francisco. He had taken ill on 31 Jul 1921.
- 1921: Calvin Coolidge president of the USA 1921-1929. Calvin Coolidge, vice president under Warren Harding, sworn in as president the day after Harding dies.
- 1921: Artificial life begins -- the first robot built.
- 1921: John Larson, a University of California medical student, invented the modern lie detector (polygraph), used by police since 1924.
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| 3 | 1922 | - 1922: Insulin invented by Sir Frederick Grant Banting.
- 1922: The first 3-D movie (spectacles with one red and one green lens) is released.
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| 4 | 1923 | - 1923: Garrett A. Morgan invents a traffic signal.
- 1923: The television or iconoscope (cathode-ray tube) invented by Vladimir Kosma Zworykin.
- 1923: John Harwood invented the self-winding watch.
- 1923: Clarence Birdseye invents frozen food.
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