Liberty Bell - Philadelphia, PA - Human Error on Waymarking.com

The original Liberty Bell was ordered from Thomas Lester of the London firm Lester and Pack, later known as the Whitechapel Bell Foundry. Upon delivery it was tested and with the first strike of the clapper, the bell's rim cracked.

Two local but inexperienced founders, John Pass and John Stow, offered to recast the bell. The bell was melted down, and cast into a new bell. However the metal was too brittle and they added 10% more copper to the bell. When the bell was struck in a public ceremony the sound produced was described as being like "two coal scuttles being banged together". Pass and Stow recast the bell a third time. The Liberty Bell developed its well known crack sometime between 1817 and 1846. It was irreparably damaged in 1846, when the bell rung to commemorate George Washington’s birthday.

According to Wikipedia Web Link

In 1975, the Winterthur Museum conducted an analysis of the metal in the bell, and concluded that "a series of errors made in the construction, reconstruction, and second reconstruction of the Bell resulted in a brittle bell that barely missed being broken up for scrap". The Museum found a considerably higher level of tin in the Liberty Bell than in other Whitechapel bells of that era, and suggested that Whitechapel made an error in the alloy, perhaps by using scraps with a high level of tin to begin the melt instead of the usual pure copper. The analysis found that, on the second recasting, instead of adding pure tin to the bell metal, Pass and Stow added cheap pewter with a high lead content, and incompletely mixed the new metal into the mold. The result was "an extremely brittle alloy which not only caused the Bell to fail in service but made it easy for early souvenir collectors to knock off substantial trophies from the rim"