9781422283271

A gristmill uses the power of flowing water to turn a wheel that causes gears to rotate, crushing wheat into flour.

ing (carving each needed piece meticulously by hand), but in 1753 he finally completed the project. His clock, which struck on the hour, kept perfect time for more than five de- cades and is widely acknowledged as the first clock ever made entirely in the US. Banneker’s next set of invention adventures began when he became friendly with the Ellicott brothers, part of a Quaker family who built a series of gristmills in Baltimore County in the 1770s. In 1788, using tools and books he had borrowed from the Ellicotts, Banneker tried predicting the timing of a solar eclipse. While he was slightly off in his cal- culations, he found later that the error was due to a mistake in something he had read rather than an actual miscalcula- tion on his part. In early 1791, Banneker helped another member of that family, Major Andrew Ellicott, to survey the new federal city that would become Washington, D.C. The new capi-

Benjamin Banneker

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