In 1503, Joseon developed cupellation — a technology to e... | funfact.wiki | funfact.wiki
In 1503, Joseon developed cupellation — a technology to extract silver from lead ore — which was transmitted to Japan. Japan went on to produce 30% of the worlds silver, using this wealth to build national power, which ultimately returned as the Imjin War.
In 19th-century Paris, all city clocks were synchronized via compressed air. Around 300km of underground pipes carried minute-by-minute pressure pulses from a central master clock to over 4,000 clocks. When the 1910 Paris flood hit, every clock in the city froze at 10:53 AM.
Walking with same-side arm and leg moving together (lateral walk) is actually the most common gait among mammals — dogs, cats, elephants, and deer all walk this way. In Edo-period Japan, people also walked this way, using a style called "nanba."
Highway and railroad curves are not circular arcs — they use a special shape called a "clothoid" (Euler spiral). Its curvature changes gradually, so centrifugal force increases smoothly when transitioning from a straight section to a curve, rather than hitting suddenly.
Hypodermic injection needles aren't made by drilling holes. A flat steel strip is rolled into a tube, welded, then pulled through progressively smaller holes. Larger gauge numbers mean thinner needles — 18G means the wire passed through 18 holes.