"Chris Hogg" wrote in message
...
I can understand the problem of circular calibration, but I'd never have
been able to discover or even guess what it was from the phrase, assuming
I
hadn't already heard of it.

I've been familiar with the phrase for many decades. At some time in
the past I wanted to be able to link to it on occasions such as this,
so did a Google search but don't now remember the search terms. I
saved the link in my 'favourites' list.

Despite doing physics to A level and then elec eng at university, I've never
heard of it before today, either by name or as a story, though I've heard
many times of circular calibration.

The sea captain and watchmaker could also be an example of a systematic
error getting gradually worse. If the watchmaker is accurate and the sea
captain takes a couple of seconds to adjust his clock in sync, that error
(plus a similar error on the watchmaker's part when he syncs to the
captain's time) will affect the watchmaker's new time - and so on
repeatedly.