White smoke: signalling a new pope down the ages

White smoke rises from the chimney on the roof of the Sistine Chapel meaning that cardinals elected a new pope on the second day of their secret conclave on March 13, 2013 at the Vatican.[AFP]

When Catholic cardinals vote in the conclave, they then burn their ballots, sending up black smoke to signal no decision or white smoke to show they have chosen a new pope.

The centuries-old tradition of using smoke has changed over time -- as has the technology used.