> I would definitely argue that the seven-day week was instituted by Someone other than man, however. :)

Heh, you're right.

I'd say that the use of "hour" in the Bible is simply using a man-made term, though. In the Old Testament, it only appears in the book of Daniel, and it's not defined there, as "week" is in Genesis, simply used. So it is probably irrelevant how accurate an hour was then as compared to now.

I went on to look up "minute," which does not occur in the Bible at all. It's too bad I can't readily tell if "second" is used as a measure of time. Anyone interested would only have to check 173 instances of the word's use, which isn't bad, all things considered.

"Fortnight" is surely man-made, though obviously based on the week.