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…
Everything difficult about a watch comes from being small, portable and attached to somebody. The timekeeping principles are the same as a clock; the conditions are entirely different. Here are…
The shaft is not holding the canopy up. A sliding collar pushes struts outward, those push the ribs out, and the fabric between them is stretched tight - which is…
There is a widespread mental model of a kite that treats the string as a leash, restraining something that would otherwise escape.
That model produces a specific prediction: cut the…
There is a useful question to ask about any everyday object: what did people do before it, and did they think they had a problem?
For most tools the answer…