China Marks International Anti-Drug Day 1 of 9 Both fire and smoke were used along the Great Wall of China as a way for soldiers to alert each other of impending attack. It is believed that they were able to send messages nearly 500 miles away in mere hours. In this image, Smoke rises from a watch tower from the Great Wall on June 26, 2006 in Beijing. Habemus Papam! Crowds in St Peter's Square rejoiced today after the 115 cardinals sequestered in the Vatican finally chose the Catholic Church's new Supreme Pontiff, Pope Francis I. But their decision wasn't tweeted, or texted, or even put out there on Facebook. No, the Vatican does it old school: with smoke. Here's what happens: After they vote, the Cardinals burn paper with "I choose as Supreme Pontiff," written on it (in Latin), and the resulting smoke rises out of a small chimney atop the Sistine Chapel. If it emits black smoke, they haven't quite made their minds up. But if it burns white, we have a pope. It might not be a very 21st Century method, but it's simple and highly visual. Indeed, we've been using smoke signals to communicate with one another for centuries. Here, TIME presents a visual history of smoke signals, the original status update.