On 22/03/18 18:00, Jim K wrote:
PeterC Wrote in message:
On Thu, 22 Mar 2018 11:24:29 +0000 (GMT+00:00), Jim K wrote:

Max Demian Wrote in message:
On 21/03/2018 23:10, Jim K wrote:
Max Demian Wrote in message:
On 21/03/2018 20:22, Jim K wrote:
Johnny B Good Wrote in message:

It was not I who was obsessed with bridges needing to be "flat", it was
you. I think you are conflating Brian's mention about 'flatness' and
curvature of the Earth corrections with my not being able to find a
curvature of the earth divergence figure for the Severn bridge to compare
against the figure that Tim+ had found for the Humber bridge. I made no
mention of 'flatness' until you introduced it into this sub-thread.

--
Johnny B Good


Oh dear. Put very simply, if one wasn't trying to build
something flat, why would one be bothered with calculations to
the mm to allow for curvature of the earth ? !

To ensure that it's curved to the right degree?

Such as a.........?
(not a bridge shurely, if anything they are more likely to be hump
backed...)

A long, perfectly flat bridge deck would effectively dip in the middle
from a gravity POV. You would probably want it to follow the curvature
of the Earth.

--
Max Demian


If it was "perfectly flat" shurely it wouldn't dip anywhere?

Flat is not horizontal, 'level' is. A roof can be at 45 deg. and flat (as is
a wall). A large 'flat' roof (as commonly used) would have a pool of water
in the middle after rain, as the edges are up with reference to gravity
(assuming that the roof is level re. gravity).
--
Peter.
The gods will stay away
whilst religions hold sway


Your roof will fail ;-)

So you're now saying something described as "perfectly flat" like
a bridge deck, can have dips in it? Like a snooker table...?
Mmm...

No. He is saying that a pool of water on Earth, is convex, like the
atlantic ocean...


--
Microsoft : the best reason to go to Linux that ever existed.