On Sun, 8 Oct 2006, Richard J. wrote:

Ralph Diehl wrote:

Yes, I abandoned that object for about the same reason.

I'm playinng with the shadow of the tate modern chimney now, it's a
bunch clearer.

The chimneys of Battersea Power Station are also very good.

Somebody said it was about 11am, it's not quite 11:30am according to
the angle I got.

I'm trying to remember the distance down to the river (how many
feet lower the river level is from the base of chimney), it's been
nearly a year since I was last there. (I live about 6K miles away
from it)

The river level varies by up to 7 metres depending on the state of the
tide, so that may not be a good shadow to choose.

Ah, but if we can deduce the height of the tide from a feature on the
Thames, we can correct for that. And we'd have a double-check on the date
and time via the tide tables. If you look at the Thames barrier or the
Woolwich ferry piers, you can see the tide is definitely on the flood, and
i'd say coming in at quite a rate, which would mean it was something like
halfway between low and high tide.

This stepped bank at the mouth of Barking Creek:

http://maps.google.co.uk/maps?z=19&l...6,0.096506&t=k

Could be useful, if we had some way of calibrating it! The mudflats at
Erith would also do.

Alternatively, how about the monumenty thing in Regent's Park:

http://maps.google.co.uk/maps?z=19&l...,-0.150633&t=k

Too short to measure accurately?

tom

--
When you mentioned INSERT-MIND-INPUT ... did they look at you like this?