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Date |
Event(s) |
| 1 | 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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| 2 | 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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| 3 | 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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| 4 | 1924 | - 1924: The dynamic loudspeaker invented by Rice and Kellogg.
- 1924: Notebooks with spiral bindings invented.
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| 5 | 1925 | - 1925: The mechanical television a precursor to the modern television, invented by John Logie Baird.
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1921 - 1925 (4 years)