Sicilian coins displaying terrible Scylla on one and an ancient electric lighthouse beacon on the other.
The coin on the left above depicts the hideous monster Scylla, and the one on the right displays a searchlight—with its light rays shooting out from the statue standing on top of an ancient Sicilian lighthouse that once guided ships through the dangerous currents that still plague the Strait of Messina. The main current runs from south to north, but a subsidiary current flows in the opposite direction. They usually alternate about every six hours and sometimes generate enough opposition to rip out seaweed from the bottom of the sea and throw up fish to the surface.
The ancient lighthouse once stood at the entrance to the harbor of Messina, opposite the rock of Scylla. According to Homer, Scylla was a terrifying monster, yelping like a dog, with twelve feet, six long, snaky necks, and on each a hideous head, and therein three rows of shark-like teeth set thick and close, with which she devoured those whom she had snatched from ships or the deep. She frightened Sicilians so much that they saw fit to advertise the hazard by stamping an image of her on one side of their coins. Ancient Sicilians minted these silver denarii between 42 and 40 B.C. The coin on the left above displays Scylla, with her threatening tentacles. The one on the right shows the sea god Neptune holding his trusty trident in one hand and an electric mirror, with light rays clearly shooting forth, in the other. Its beam is pointed downward, to light the strait and to spot Scylla waiting to devour naive seamen struggling through the darkness below. Notice that no smoke is belching out from Neptune’s light beam—or from anywhere on the lighthouse for that matter—so electricity rather than a smoking fire was apparently generating its light rays.
For the Arab geographer Al Bakri's unique physical description of another ancient electric lighthouse, the Pharos of ancient Alexandria, one of the Seven Wonders of the Ancient World.
You will never get all the facts here. There are many more in The Electric Mirror. This Web page has many and shines all right, but the book has more ancient technology and carbon arc light!