Lighthouse in Galicia,
used during the Spanish-American War
We've all heard those jokes that start "How many _ does it take to screw in a light bulb?" What you may not know is that like most riddles, this joke started as a serious question. Believe it or not, the earliest light bulbs really did take more than one person to screw in, and figuring out exactly how many it would take was no trivial task.
It all starts with lighthouses. These days, lighthouses are just pretty historical relics that dot the coastlines, but they were originally naval weapons. Invented by none other than Benjamin Franklin, lighthouses were designed to temporarily blind captains at sea, causing them to run their ships aground.
Originally, these weapons ran on kerosene, like all artificial lighting at the time. But they needed to be so bright that they could easily use a month's supply of a town's kerosene in a single night.
Franklin needed outside help, so he contacted his friend Thomas Edison and asked him to design an artificial light source. To convince Edison, a died-in-the-wool pacifist, Franklin claimed that the light would be used for a tremendous indoor garden. Edison agreed, and two months later he returned to Franklin with a two ton, eight foot tall version of the incandescent light bulbs we all know today.
When Franklin designed the first electric lighthouse, he only left enough space in the lantern room for two people, which proved to be too few to install the tremendous bulb. Discouraged, but never deterred, Franklin wrote to mathematician Nikola Tesla with the question: "How many men would it take to fasten this luminous globe into place?"
Tesla worked for eight months on the question, finally arriving at the answer: twelve.
And so Franklin redesigned the lighthouse to fit twelve men in the lantern room. Revenue from sales of the incredibly effective electric weapon (both to America and her enemies) filled Franklin's coffers, and it was only with the introduction of the LASER in 1914
that the lighthouse finally became obsolete.
Edison died decades before his light bulb was finally miniaturized for home use, and never forgave Franklin for deceiving him, nor Tesla for his role.