How a scientific outsider came up with a revolutionary theory of light and saved untold numbers of lives.
Augustin Fresnel (1788–1827) shocked the scientific elite with his
unique understanding of the physics of light. The lens he invented was a
brilliant feat of engineering that made lighthouses blaze many times
brighter, farther, and more efficiently. Battling the establishment, his
own poor health, and the limited technology of the time, Fresnel was
able to achieve his goal of illuminating the entire French coast. At
first, the British sought to outdo the new Fresnel-equipped lighthouses
as a matter of national pride. Americans, too, resisted abandoning their
primitive lamps, but the superiority of the Fresnel lens could not
be denied for long. Soon, from Dunkirk to Saigon, shores were brightened
The Fresnel legacy played an important role in geopolitical
events, including the American Civil War. No sooner were Fresnel lenses
finally installed along U.S. shores than they were drafted: the Union
blockaded the Confederate coast; the Confederacy set about thwarting it
by dismantling and hiding or destroying the powerful new lights.