Black or white smoke, did they pick a pope?

A statue dwarfs the chimney on the roof of the Sistine Chapel where cardinals will gather to elect the new pope during the conclave at the Vatican, Monday, March 11, 2013. AP PHOTO/DMITRY LOVETSKY

VATICAN CITY—Forget all the artistic masterpieces. The most gazed-at item at the Vatican this week will be a humble, copper, two-meter-high chimney that will pipe out puffs of smoke to tell the world if there’s a new pope.

Black smoke means “not yet.” White smoke means “pope elected.”

When three Vatican firefighters hoisted the chimney to its perch a few days ago, it was a visual cue that preparations for the conclave to elect retired Pope Benedict XVI’s successor were in high gear.

The Sistine Chapel and its magnificent Michelangelo-frescoed ceiling were made off limits to tourists. Two metal stoves were then installed in a far corner, away from the chapel’s altar and the area where the cardinals will write out their picks for the next pope on slips of paper.

In the past, counted ballots went into just one iron stove along with damp wood chips or wet clumps of straw to create black smoke if the vote didn’t yield a pope.

But the smoke signal system has been unreliable, triggering nervous cries of “It’s white” and emphatic choruses of “No, it’s black!” in the various tongues of the faithful and curious who flock to St. Peter’s Square for a glimpse of the chimney.

So in 2005, for the conclave that made Benedict pope, the Vatican tried something different: A second stove was installed that produces smoke from a chemical compound whipped up by the Vatican’s own technicians. The smoke from the burned ballots from the first stove and the colored smoke from the second stove were funneled up one pipe that leads to the chimney and the outside world.

But that solution hardly made the distinction between black and white smoke any clearer—and confusion still was the order of the day.

It’s a big unknown whether the Vatican has improved its technology this time around.

The sequestered cardinals will have a first chance to vote early Tuesday evening. If they fail to pick a pope, the next few days can see as many as two rounds of balloting each morning and two rounds each afternoon, until one man clinches the required two-thirds majority.

The weather forecast promises to cloud the situation even further.

Rain, sometimes heavy, is predicted through Thursday, with Friday’s skies forecast to be partly cloudy.

The Vatican says it will shine spotlights on the chimney for the evening votes.

In following the conclave, it will be wise not just to keep your eyes open, but your ears as well: The bells of St. Peter’s Basilica will be set ringing when a new pope has been chosen.