Database: The Solar Cannon of the Palais-Royal

Designed in 1786 by watchmaker and inventor Robert Rousseau, the solar cannon allowed strollers at the Palais-Royal to adjust their timepieces: when the sun reached the meridian, a magnifying glass was arranged so that the sun's rays were directed to the touch hole of a small cannon. At noon precisely, it went off with a bang! A restored cannon works to this day.