Technology

The convention of expressing TV and monitor screen sizes by diagonal length began because early cathode ray tubes were circular. A single diameter sufficed, and even after screens became rectangular, the uniform 4:3 aspect ratio meant diagonal length alone still worked.

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.

When bees are repeatedly exposed to explosive scents followed by sugar water, they eventually extend their tongues at the smell alone. A real device was built with 36 trained bees in sensor cartridges as an explosive detector. Training a dog takes months, but bees need only a few hours.

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.

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.

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.