Powerful winds produced by an Oct. 21 gale appear to have taken a toll on the Devils Island lighthouse in the Apostle Islands, said Park Superintendent Lynne Dominy. About a 2-foot diameter piece of the lighthouse's Fresnel lens came loose from its mounting and shattered on the deck below.
In a news release issued Tuesday, Dominy said: "Heavy winds, big waves and ice constantly damage our docks, buildings and shorelines. Having this type of damage to our only Fresnel lens is heartbreaking, and we are working on ways to address this damage."
During the Oct. 21 storm, a 65-mph gust was recorded on Devils Island at 3 p.m., the National Weather Service said. The highest sustained wind speed reached 54 mph at 3:30 p.m.
Park staff members returned to the lighthouse on Oct. 28 to pad and stabilize the remaining portions of the lens. They plan to consult with glass-conservation and historic-preservation experts.
Fresnel lenses are designed to use multiple prisms that can refract light, making the beam visible over long distances. The 118-year-old Devils Island third order Fresnel lens was the only original Fresnel lens still in place in an Apostle Islands lighthouse. The lens was manufactured in Paris by the Henry-Lepaute Clock and Lens Works.
The lens was temporarily removed from the lighthouse in 1989, when the tower was modernized and equipped with a smaller beacon powered by solar panels.
However, local residents and the National Trust for Historic Preservation worked to return the lens to Devils Island in 1992.