[xyclos]

And I suppose that's also the origin of measuring speed in "knots" (?)

[haylem]

Yes

Update: my original answer was short because, well, I'm a sailor. But for more, see: https://en.wikipedia.org/wiki/Knot_(unit)

[arnarbi]

Yep. For scale: if you count for one minute, a knot every 30m or so on the string will give you your speed in nautical miles per hour (=knots)