I imagine we’ve all been lost while driving at night, looking for a sign or landmark to help us find our way. For centuries, before recent technology existed, if you were lost at sea, the only things which would help you were the stars (on a clear night) or the beam from a lighthouse.

Lighthouses have existed for centuries. The first were open fires on hill tops near the shore. Later towers were constructed with fires on top of them. By the 1800s, tower lighthouses existed with multiple lamps, each with a mirrored reflector behind it, but their lights were only visible 3 miles away – not far enough to warn of many off shore dangers.

A French civil engineer, named Augustin Fresnel, decided to tackle this problem.

Augustin Fresnel was born in 1788, the year before the storming of the Bastille, the son of an architect. Even though he was sickly as a child, as he was throughout his entire life, he still entered a technical college in Paris at age 16. By age 21, he was a fully licensed civil engineer, a government employee building roads across France.

Haunted by thoughts of an early grave, due to his frequent illnesses, he worked building roads as his day job, but devoted his nights to science experiments. By 1815, age 27, he began experimenting with light.

Luckily for the advancement of science, Napoleon escaped from Elba in 1815. You see, when Napoleon escaped, he returned to France and led his armies against the King’s armies. Augustin Fresnel sided with the King’s armies. So when Napoleon won, Augustin Fresnel lost his government job. This meant he could spend his entire time, both day and night, experimenting with light.

At that time, the big scientific debate about light was whether it was made up of particles or waves. Augustin Fresnel sided with the wave proponents, but he was the first to create mathematical equations which described light’s movement as waves. He published his first scientific paper on light, with those equations, in 1815.

Unfortunately, Napoleon was defeated at Waterloo after only 4 months in power, and Augustin Fresnel got his day job back. But he continued to experiment with light. The next year, Augustin Fresnel conducted experiments which confirmed what his equations had predicted. A few years later, when the Academy of Sciences offered a prize for the best scientific paper on light, Augustin Fresnel won that award.

Augustin Fresnel wrote: "All the compliments that I have received from my scientific colleagues do not give me as much pleasure as the discovery of a theoretic truth, or the confirmation by experiment of a calculation."

In 1821, age 33, Augustin Fresnel decided to tackle the lighthouse problem.