Articles

TLDR: Early cameras required extremely long exposure times. Moving objects like people and carriages were too fast to be captured, becoming invisible or just a faint blur, which created the illusion of empty streets.

TLDR: Chimneys were built crooked to route them from a fireplace on an outer wall to the central, more stable peak of the roof. This also improves draft and helps keep rain out.

Eggs are egg-shaped because the asymmetrical shape is structurally strong, packs efficiently in a nest, and prevents them from rolling off ledges by making them roll in a tight circle.

TLDR: Blue lines were historically invisible to early copiers, making them disappear on copies, while the attention-grabbing red margin line clearly marked a space for a teacher's or editor's notes.

TLDR: Those blocks are sacrificial anodes. They are made of a metal that corrodes more easily than the ship's hull. In saltwater, the blocks get destroyed by electrical currents and corrosion on purpose, so the important parts of the ship, like the hull and propeller, are protected. It is much cheaper to replace the blocks than to repair the ship.

TLDR: Cannonballs are left in old walls intentionally as memorials to past battles, or because it was too difficult and damaging to remove them.