The Fresnel lens turned a feeble flame into a beam visible twenty miles out to sea. Augustin-Jean Fresnel's 1822 invention collapsed a solid lens into concentric prism rings around a central bullseye — a beehive of cut glass cradled in brass, each ring bending stray light back into a single shaft.

This system lives inside that lantern room at night. The ground is near-black; the optical glass glows aqua-green from its iron content, the brass armature catches a bronze gleam, and a warm amber-white beam cuts the dark. Refined Roman-capital titling and engraver's body type frame it like a 19th-century optical plate.