The question worth asking at the entrance to any tunnel is what problem made digging cheaper than going around. Here are seventeen, and the answers.
1. Pedestrian River Tunnels
Source:…
Source: Wikipedia
Anyone who has left a tool in the garden knows what happens to iron. A gate goes orange, a railing flakes, and given a few seasons the metal is…
There is a security feature in almost everyone's pocket that has been doing its job for over three hundred years, and almost nobody knows what it is for.
Look at…
The useful way to read a lock is as a question about what the key is proving. Every mechanism below tests something slightly different, and the differences are the history.…
Almost every unit of time you use is a measurement of something physical.
The day is the Earth turning once. The month is roughly the Moon going through its phases.…
The mechanism is usually the same: a word is used loosely, the loose sense becomes common, and the precise one falls away. Here are fifteen that travelled unusually far.
1.…