French physicist Léon Foucault was born on September 18, 1819. After being taught at home, Foucault entered medical school. He switched to physics, however, due to his fear of blood. His first field of interest was Daguerre’s photographic process. He continued to work in the field of light, eventually proving that it moves more slowly through water than through air, disproving Newton’s theories. Foucault’s best known for his experiments about the earth’s rotation. He suspended a pendulum from the center of the dome of the Panthéon, the resting place of French heros, to prove his theories. His simple-seeming experiment was considered so revolutionary that other Foucault Pendulums were suspended in cities throughout the world. Since there was no television in 1851, these displays drew crowds.
I struggled mightily with physics in high school, so I don’t have the foggiest notion of what any of his experiments actually mean. Suffice it to say, Foucault was showered with honors, including the Légion d’Honneur. He died on February 11, 1868. Like Daguerre, his is one of the 72 names of the men of science inscribed on the Eiffel Tower. He is not, however, buried in the Panthéon but rather in the cemetery in Montmartre. I hope that he rests peacefully there and does not rotate whatsoever.
Today’s expression is remettre les pendules à l’heure (ruh-met-ruh lay pehndool ah luhr), which figuratively means “to set the record straight.” Literally, however, it means “to put the clocks back on time.” Pendule is one of those words that has a dual meaning depending on the gender. If it’s masculine, un pendule, it means a pendulum à la Foucault. If it’s feminine, une pendule, it means a grandfather clock. If you have a clock with weights, you’ll know that gradually the pendulums descend and must be gently pulled back up to keep the clock ticking along. It’s an apropos phrase for the man who set the record straight about light – even though I just have to take all his brilliance on faith.