In honor of the United States' 250th anniversary, scientists at Penn State University have modeled the acoustic properties of the Liberty Bell, drawing on data from one of its replicas. Historians are unsure when the bell’s famous crack first appeared, but it is believed to have happened between 1817 and 1846. An 1846 account in the Public Ledger detailed the bell's last known ringing, noting that the crack had worsened, rendering the bell 'irreparably cracked and forever dumb.' This wasn't the first crack; the bell had a rim crack shortly after its arrival in Philadelphia in 1752, and it was recast by two local foundry workers, John Pass and John Stow, twice. The second recast was deemed acceptable, but the bell fell into disuse after the American Revolutionary War. A 1975 study revealed that the bell's metal composition made it particularly brittle, leading to its eventual demise.