7 Hat Legends, Fact Checked

Common knowledge has a lot to say about hats—but is it true?
1. DANIEL BOONE WORE A COONSKIN CAP.
FALSE! While the American frontiersman Daniel Boone became one of the hat’s poster boys, he never wore one. On the contrary, as his son Nathan wrote, he “always despised the raccoon fur caps and did not wear one himself.”
2. YOU LOSE 70 PERCENT OF YOUR BODY HEAT THROUGH YOUR HEAD.
FALSE! You lose just as much heat through your head as you do from other body parts; it just feels colder because the skin on your face and head is more sensitive. (At most, you’ll lose about 10 percent of your body’s heat through your noggin.) This myth started back in the 1950s after a not-so-scientific military study dressed volunteers in survival suits and tossed them into the bitter cold. Since their heads were the only part uncovered, they lost most of their heat there.
3. VIKINGS WORE HORNED HELMETS.
FALSE! Lots of ancient people wore horned helmets! Teutonic knights, Celtic warriors, late Roman armies, the samurai, Indo-Persian warriors, Conan the Barbarian. But Vikings? Not a chance. The trope was popularized in Richard Wagner’s 1876 four-part opera, Der Ring des Nibelungen.
4. HATTERS WENT “MAD” FROM MERCURY POISONING. 
UNKNOWN. Although olde tyme hatters used mercury salts to make felt for hats, we’re not positive the practice drove them insane. It’s more likely that the phrase “mad as a hatter” isn’t even about people—it’s about snakes. Back in the 18th century, “mad” was synonymous with “venomous,” and “hatter” was a bastardization of the word “adder,” for viper. In that case, the phrase means “venomous as a viper.”
5. TIN FOIL CAPS CAN STOP BIG BROTHER FROM READING YOUR MIND.
FALSE! Actually, they make it easier. A foil cap is supposed to act as a Faraday cage, a device that—like your kitchen microwave— shields you from electromagnetic radiation. Problem is, the concept works only if the cap wraps around your entire head. In 2005, a team of MIT graduate students found that your typical foil hat amplifies the frequencies used most by the FCC—including space-to-Earth satellites.
6. THE CAP OF INVISIBILITY MAKES YOU INVISIBLE.
TRUE! In Greek mythology, gods and goddesses could wear the Cap of Invisibility to sneak past other supernatural beings unseen. We still haven’t seen one, so it must be true.
7. COWBOYS WORE COWBOY HATS.

FALSE! Invented in 1865, the classic Stetson looked more like a flat, boring version of a sombrero than the stylish, curvy hat we know today. And it wasn’t the most popular hat at the corral to begin with. In the cowboy’s heyday, most wranglers wore top hats, sailor’s caps, and—above all—bowler hats.