A striking detail from Martha Tyson’s Sketch of the Life of Benjamin Banneker (1854):

Whilst they were conversing his clock struck the hour, and at their request he gave an interesting account of its construction. With his imperfect tools, and with no other model than a borrowed watch, it had cost him long and patient labor to perfect it, to make the variation necessary to cause it to strike the hours, and produce a concert of correct action between the hour, the minute, and the second machinery. He confessed that its regularity in pointing out the progress of time had amply rewarded all his pains in its construction.

This seems to be at least plausibly true: In 1753, the 21-year-old Banneker, who had never seen a clock, borrowed a watch from a trader, made drawings of its workings, and designed a wooden clock of his own. Peter N. Stearns writes in Time in World History (2020), “Banneker, the son of former slaves, borrowed a watch from an acquaintance, took it apart, ultimately using this as a model to build an impressively accurate clock entirely from carved wooden pieces, and then capitalized on the notoriety of this product to set up his own repair operation.” The clock continued to operate until Banneker’s death more than half a century later.