Once the cardinals close themselves off in the Sistine Chapel so that voting on the next pope can begin, eyes outside turn to a chimney poking out of the chapel, clearly visible from St. Peter’s Square in Vatican City. It will release a plume of white smoke if a pope has been chosen, and black smoke if no candidate has won the required two-thirds majority of votes.
It’s a tradition that scholars date to the 19th century, when conclaves were held at the Quirinale Palace, the papal palace across town that is now home to the Italian president.
In “Behind Locked Doors,” a 2003 history of papal elections, Frederic J. Baumgartner wrote that the first evidence he found of smoke being used as a signal in a papal election was from 1823. The cardinals’ ballots were burned in previous conclaves, he wrote, but there was no record that the smoke was intended to inform the outside world of a new pope.
The smoke comes from the burning of the ballots, as well as any notes that the cardinals have taken, which are placed in a cast-iron stove after each round of voting. (One round is held the first day, and four each day from then on, with two in the morning and two in the afternoon.) The ballots are burned after two rounds of voting, unless a pope is chosen.
Until this century, wet straw was added to the stove to create the smoke’s white color. But it wasn’t always reliable.
As The New York Times reported, during the 1958 conclave, white smoke seemed to appear twice during the second day of voting. That created confusion because, in fact, a pope had not yet been selected.
