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December 9
Improved Roller Skate Invented!
On this day in 1884, Micaja Henley from Richmond, Indiana patented roller skates with ball bearings. Ball bearings are tiny metal balls that stay next to the wheel and help it turn. Roller skates were invented in Belgium more than 100 years beforehand, but those skates, which didn't have ball bearings, were very hard to turn!

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