Why do we say “hot noon” ?

"See you at noon sharp!" This is a typical French expression that you've probably heard before, and if you're not particularly punctual, it can sometimes sound like a slight threat from the person you're talking to. In this article, the Charlie Paris team explores the surprising origin of this expression. To find out, we're heading to the gardens of the Palais Royal, right in the heart of Paris…

The expression "midi pétante" is the originator of an ingenious invention, that of the solar cannon. If you've ever strolled through the gardens of the Palais Royal, you might have noticed a curious little cannon in the middle of the lawn. If you thought, like us, that it was simply a decorative statue… think again! It's actually a sundial. No, we're not talking about sofas, of course, but a solar cannon, invented by Mr. Rousseau, clockmaker at the Galerie de Beaujolais.

The cannon, installed in 1786, is unique in that it is topped with a magnifying glass, itself positioned along the Paris Meridian. This ingenious system, when the weather is favorable, concentrates the sun's rays, which, at noon, generates enough heat to light the cannon's fuse and trigger a loud detonation. Far from being a weapon of destruction, this cannon once allowed Parisians to reset their watches, in an era before automatic watches existed and mechanical movements were not always reliable and could malfunction. The cannon became obsolete and ceased firing in 1911, when France adopted the Greenwich meridian as a reference time. But the Royal Palace cannon hadn't had its last word! While the original cannon was stolen in 1998, a replica was installed in the gardens in 2002. Since 2011, every Wednesday at precisely noon, the detonation of this solar cannon can once again be heard. However, today the cannon is triggered by a pyrotechnician and no longer by the simple heat of the sun, in order to be more precise.