It was seven minutes to noon and not a cloud was in sight when a trail of smoke snaked up from the Sistine Chapel (search). "White! White!" the crowd chanted, sending pigeons fluttering from St. Peter's Square.
"We have a pope!" a priest proclaimed over Vatican Radio. Reporters rushed for telephones. Vatican guards were summoned from their barracks. Guests at a wedding in St. Peter's Basilica (search) ran out into the sunlight, leaving the bride and groom alone with the priest at the altar.
But within minutes, the smoke belching from the chimney had turned black. Apparently, the damp straw that the cardinals had added to their burning ballots had failed to catch.
No chimney in history has been more scrutinized than the simple stovepipe running up through a window in the Sistine Chapel.
In one of the Roman Catholic Church's (search) most sacred traditions — the election of their pontiff — cardinals sequestered among Michelangelo's masterpieces use the iron stove and its narrow metal chimney to communicate with the outside world.
The tradition is simple: Black smoke means a vote has failed to produce a pope; white smoke means the cardinals have come to agreement. But the gray area — and the gray smoke — has often provoked confusion, such as in the incident described above, as reported in news accounts from Oct. 26, 1958.
So great was the confusion on that Sunday — there were two false alarms — that conclave marshal Sigismondo Chigi told reporters he would have the cardinals briefed "in the hope that something can be done to remedy the situation Monday," The Associated Press reported at the time.
The solution, according to Vatican expert John-Peter Pham, was to buy black smoke bombs and pass them into the chapel. The smoke they produced was clearly black, but some of it backed into the room, prompting complaints from the cardinals, he said.
Exactly when the tradition began is unclear. In past centuries, conclaves were often held in the town where the last pope died, leaving the cardinals to come up with a means of communication on the spot. Sometimes they rang bells to signal a successful election.
Smoke was a logical choice because church tradition calls for the cardinals to burn their ballots to maintain secrecy about the conclave.
In the sixteenth century, cardinals burned their ballots in the ignition hole of a gun in the Sistine Chapel, John Allen wrote in his 2002 book "Conclave." Pope Julius III, an art lover, ordered a stove installed because he feared the smoke would damage the frescoes, Allen wrote.
Exactly when smoke signals were enshrined in tradition is unclear, but they have been used continuously at least since 1878.
There is little record of color confusion until the 1958 conclave prompted changes.
Given the trouble with the smoke bombs, the cardinals in 1963 switched to Italian army flares producing black and white smoke. In the first of two 1978 conclaves, they experimented with chemical additives, but the smoke came out gray when John Paul I was elected.
"Not only did it fail to work outside, but it was nauseous to the men inside," said Pham, a Vatican official from 1992 to 2002 who now teaches at James Madison University in Virginia.
Two months later, after John Paul I's death prompted another conclave, the cardinals were back to the army flares. But the black smoke that billowed from the chimney quickly turned gray, sending journalists scrambling to pin down the color. Vatican Radio quickly declared the smoke black.
According to some reports, the radio station was able to know because of a button installed in the Sistine Chapel after the 1958 debacle to alert Vatican Radio to a decision. Some say the button alerts Vatican officials, who in turn pass along word to the radio.
The Vatican has never commented on the reports.
On Saturday, the Vatican plans to install the stove, a gray iron cylinder, in the Sistine Chapel. Workers have been seen on the slanted roof of the chapel in recent days, apparently preparing the chimney.
Archbishop Piero Marini, master of ceremonies for liturgical celebrations, announced last week that the Vatican was trying to improve the burning procedure this year to make the color more easily identifiable. It was unclear whether that meant new chemicals would be added.
But he said that when a new pope is chosen, the Vatican will ring the bells of St. Peter's Basilica in addition to burning the ballots, "to make the election of the pope clearer."
"This way," he said, "even journalists will know."