Character

Every light has a rhythm of its own — a flash every few seconds, or a group of them. Sailors read the pattern, not the brightness.

Range

Nominal range assumes clear air. In haze the useful distance can halve, which is why fog signals outlived many of the lamps.

Optics

The stepped lens gathers light that would otherwise scatter and throws it flat across the water. A small flame reaches surprisingly far.

Keepers

Logs were kept hourly: wind, visibility, the hour the lamp was lit. The handwriting changes every few years and tells its own story.