Augustin-Jean Fresnel, a nineteenth century French physicist, is credited with inventing the compound lenses still widely used in lighthouses. A Fresnel lens resembles a giant glass beehive with a lamp at the center, and rings of glass prisms above and below the lamp bend and concentrate the light into a focused bright beam. Before this invention, lighthouses used mirrors and could be seen only at short distances, but a Fresnel lighthouse lens light can be seen from twenty or more miles away. Fresnel lenses were made in sizes called orders, from first order downward, and the Harbor Beach Lighthouse used a Fourth Order lens, a type common on the Great Lakes and used in major harbor lights to lead mariners into channels and to mark shoals and islands. To help sailors identify their location, lighthouses used unique flash sequences, and Harbor Beach showed white for one second, a four second eclipse, red for one second, and a four second eclipse. The original Fresnel lens was installed in eighteen eighty-five and operated continuously until it was removed; it is now displayed in the Grice House Museum in Harbor Beach. The lighthouse now shines with an exact replica of the original lens in appearance, while the original was conserved in the nearby Grice Museum because of its high value and concern for its safety a mile offshore. Over the years several different lenses were installed in the lantern room, but none matched the brilliance of the original. The replica lenses crafted by Dan Spinella at Artworks Florida match the originals in appearance and performance except that their prisms are acrylic made by three-D printing and their light source is a high-efficiency LED three hundred sixty degree bulb; the brass components are hand polished to a high-gloss finish. This was the fifteenth lens Artworks Florida built and installed in the U.S. More than ninety-five donors raised nearly sixty-five thousand dollars for the lens and motorized base, and the completely solar-powered lighthouse required added capacity to supply both the new lens and the exterior lighting. Harbor Beach Lighthouse is one of the very few active lighthouses in the world lit at night. The lighthouse became the symbol of the Harbor Beach community, which began as a bay on Lake Huron's sunrise shore in the mid-eighteen hundreds when the area first stirred as a lumber port. Local people petitioned Congress for eleven years to continue construction funding that eventually exceeded one million dollars and completed the harbor of refuge and lighthouse in eighteen eighty-five. For decades the harbor was recognized as the world's greatest man-made harbor and it remains the largest freshwater harbor in the world.