There is a common assumption that sealing a letter was about privacy, and it misses what the object was for.
A seal provides no privacy whatsoever. Anybody determined to read…
There is a class of object that has to work with nobody supervising it, in public, permanently, and postboxes are among the clearest examples.
Before they existed, a letter had…
There is a reason water clocks were difficult and sand timers were easy, and it comes down to a surprising difference between liquids and piles of small solid grains.
A…
There is a question about weathervanes that catches almost everybody out, and it concerns which way the pointer faces.
The natural assumption is that the arrow shows where the wind…
A stair is a compromise between space and effort, and the dimensions that make one comfortable are older than any regulation that now enforces them. Here are fifteen.
1. Every…
Both of these are recent inventions that look obvious in retrospect and took a very long time to arrive, and both do something more specific than they appear to. Here…