Re: Clockwise without clocks

H. S. Teoh wrote at 2005-04-01 09:10:58 (-0800)
 > On Fri, Apr 01, 2005 at 11:40:56AM +0100, Tim May wrote:
 > > B. Garcia wrote at 2005-03-31 17:11:40 (-0800)
 > >  > All of these arguments about if wheels turn left or right or things
 > >  > roll left Vs. right when you're in a cart or whatever, is why I
 > >  > suggested "forward rolling" and "backward rolling" - from the point
 > >  > of view of someone looking at it from the side.  If you take a
 > >  > round log from a tree, and push it away along the ground it rolls
 > >  > forward - clockwise to an observer looking at it. If you pull it
 > >  > back to you the thing rolls backward, counter-clockwise to someone
 > >  > looking at it.
 > >
 > >
 > > Uh, Barry, unless I'm missing something, that doesn't work.  You're
 > > defining the motion according in terms of an observer looking at it
 > > from "the side", but there are two sides, and they'll see different
 > > things.
 > >
 > > If I'm rolling this log eastward, for example, an observer to the
 > > north will see it turning anticlockwise while an observer to the south
 > > will see it turning clockwise.
 >
 > Yes, but the person who sees it rolling anticlockwise will always see
 > it moving to *his* left, and the person who sees it rolling clockwise
 > will always see it moving to *his* right. The two of them may not
 > agree which way the log is rolling, but that's beside the point. The
 > point is that clockwise is consistently "to the right" of the
 > observer, and anticlockwise is consistently "to the left" of the
 > observer.
 >
 >

I know that, Teoh.  I wasn't disagreeing with what _you_ said.  Barry's
discription doesn't mention left and right, but forward and backward.