The Joy of Algorithms.

I've just asked Google the distance from the Lizard Peninsula in Cornwall to Dunnet Head, the most northerly point of the Scottish mainland.

Google tells me it is 803 miles, which I believe, and that it would take me 11 days to walk it, which I don't.

I think Google would have me walking 24 hours a day, at 3 miles an hour.

This shows how poorly Google knows me. My average walking speed is over for miles an hour...

(I have no intention of walking the length on mainland Britain, but was curious to see the distance. I've been reading about Richard Long, who walked thirty three miles a day for thirty three days from Lizard to Dunnet Head, a distance of 1089 miles. Presumably he didn't have Google to pick the shorter route for him. I doubt I could manage thirty three miles a day; I reckon 25 might be doable, at 3mph, perhaps. Over a month. )