Derepas 巴黎，皇家宮廷編號 24，
320 mm，約 1830
A collection of 14 sun watches
Derepas à Paris, Palais Royal no. 24, 320 mm, circa 1830
Noon cannon sun dial on a signed and engraved marble base
The cannon was loaded every day and designed to fire at noon. A mounted lens was set to focus the rays of the sun on the firing pan loaded with gunpowder at exactly noon and igniting it.