On 2016\01\07 11:02, Roland Perry wrote:
In message , at 06:14:30 on Thu, 7 Jan
2016, Roland Perry remarked:
The Great Ouse is tidal up to Brownshill Staunch, about 4 km upstream
of Earith. Though curiously (to the uninitiated) it's non-tidal
downstream of Earith.

That'll be Hermitage Lock, hiding in plain sight:

https://goo.gl/maps/YKR6xFHVrYq

...for the Great Ouse via Ely. The Environment Agency deems that the
Bedford Rivers are also part of the Great Ouse though, so that bit of
the downstream will be tidal. But it's very hard to see any tidal
component to the levels recorded here, which is about halfway to the sea
from Earith:

http://apps.environment-agency.gov.uk/river-and-sea-levels/120730.aspx?stationId=6245


As opposed to the next measuring point north of the

http://apps.environment-agency.gov.uk/river-and-sea-levels/120731.aspx?stationId=6290


I wonder if there's a finesse in the expression "tidal", which means "up
to the first lock", rather than "the part of a river whose level is
affected by the tides".

People usually say the Thames is tidal to Teddington Lock, even though
the lowest lock is at Richmond Weir.

On 2016\01\07 15:01, wrote:
On Thu, 7 Jan 2016 12:46:15 +0000, Basil Jet
wrote:
People usually say the Thames is tidal to Teddington Lock, even though
the lowest lock is at Richmond Weir.
As well as the lock there sluice gates which are lifted when the tide
has risen high enough and the tidal flow is unimpeded.
When those are open craft just proceed past without using the lock.

I can't see them in Google. Why don't they just open both lock gates and
let the boats through there?

In message , at 12:14:26 on Thu, 7
Jan 2016, Clive D. W. Feather remarked:
I wonder if there's a finesse in the expression "tidal", which means
"up to the first lock", rather than "the part of a river whose level
is affected by the tides".

Don't know.

The OS 1:50,000 maps show the Great Ouse as tidal from the sea to
Denver, then non-tidal to Earith, then tidal to Brownhill. The New
Bedford is shown as tidal throughout; the Old Bedford and Delph as
non-tidal throughout. The boundaries are all things like sluices.

One of the reasons I'm not convinced that the New Bedford is tidal in
the sense of going up and down twice a day is that when it floods at
Welney the water doesn't flow away to the Wash for weeks.
--
Roland Perry

On 2016\01\07 17:58, wrote:
On Thu, 7 Jan 2016 15:54:19 +0000, Basil Jet
wrote:

On 2016\01\07 15:01, wrote:
On Thu, 7 Jan 2016 12:46:15 +0000, Basil Jet
wrote:
People usually say the Thames is tidal to Teddington Lock, even though
the lowest lock is at Richmond Weir.
As well as the lock there sluice gates which are lifted when the tide
has risen high enough and the tidal flow is unimpeded.
When those are open craft just proceed past without using the lock.

I can't see them in Google. Why don't they just open both lock gates and
let the boats through there?

When the google river boat went through it was obviously high tide,
https://goo.gl/maps/Zb65Ca54SD92

In the down position they look like this.
http://www.geograph.org.uk/photo/587456

The Lock would impede the flow of the incoming tide even with all the
gates open as it is a lot narrower than the width of the opened sluice
gates.

Wouldn't the rising tide just go over the weir?

Also using the lock means it would be a bottleneck, High tide often
means higher traffic as many boats prefer to move on the deeper water.
You would find it difficult to pass upstream and downstream traffic
through the lock at the same time.

Fair point.

In uk.transport.london message INGdnR4_98HNhBbLnZ2dnUU78WGdnZ2d@giganew
s.com, Mon, 4 Jan 2016 19:16:00, posted:

Tidal no, but coal to the generating station came in by river until it
closed in 1966. It was still the distribution point for supplies in central
Cambridge until after I arrived and was surprised to find 210v (nominally,
actually 205v) electricity again, it having gone from Putney in the 1950s.

A select portion of central Cambridge still used 110 volt
(approximately) lighting in about 1965. I can, if desired, explain why.

--
(c) John Stockton, Surrey, UK. Turnpike v6.05 MIME.
Merlyn Web Site - FAQish topics, acronyms, & links.

In message , Roland Perry
wrote:
One of the reasons I'm not convinced that the New Bedford is tidal in
the sense of going up and down twice a day is that when it floods at
Welney the water doesn't flow away to the Wash for weeks.

But is that the New Bedford flooding or the Old Bedford or Delph?

Anyway, heavy flow from upstream could overwhelm the tidality.

--
Clive D.W. Feather | Home:
Mobile: +44 7973 377646 | Web: http://www.davros.org
Please reply to the Reply-To address, which is:

In message , at 07:05:35 on Fri, 8
Jan 2016, Clive D. W. Feather remarked:

One of the reasons I'm not convinced that the New Bedford is tidal in
the sense of going up and down twice a day is that when it floods at
Welney the water doesn't flow away to the Wash for weeks.

But is that the New Bedford flooding or the Old Bedford or Delph?

Anyway, heavy flow from upstream could overwhelm the tidality.

The point at which "flooding is possible" measured on the New Bedford is
2.4m AOD, and it's pretty much spot on that today.

The peak tides at Kings Lynn are currently is 2.2m (and the average
around 0.6m) so that's not going to be flowing inland as far as Welney,
nor does the chart for Welney show any indication of waters backing up
in tune with the tides.

We should revisit this in the summer when it's drier (or perhaps find
some historic data).
--
Roland Perry

In message , at 08:54:44 on Fri, 8 Jan
2016, Roland Perry remarked:
In message , at 07:05:35 on Fri, 8
Jan 2016, Clive D. W. Feather remarked:

One of the reasons I'm not convinced that the New Bedford is tidal in
the sense of going up and down twice a day is that when it floods at
Welney the water doesn't flow away to the Wash for weeks.

But is that the New Bedford flooding or the Old Bedford or Delph?

Anyway, heavy flow from upstream could overwhelm the tidality.

The point at which "flooding is possible" measured on the New Bedford
is 2.4m AOD, and it's pretty much spot on that today.

The peak tides at Kings Lynn are currently is 2.2m (and the average
around 0.6m)

for clarity, that means today's mid-tide, not an average of high tides.

so that's not going to be flowing inland as far as Welney, nor does
the chart for Welney show any indication of waters backing up in tune
with the tides.

We should revisit this in the summer when it's drier (or perhaps find
some historic data).

--
Roland Perry

On 07/01/2016 23:45, Dr J R Stockton wrote:

A select portion of central Cambridge still used 110 volt
(approximately) lighting in about 1965. I can, if desired, explain why.

That would be interesting to know.

I went to a shop in Cambridge in 1965 to buy a kettle. I was surprised
to be asked if I wanted it 110 or 230 volt. There must have been a lot
of domestic appliances scrapped at the time of conversion.


--
Clive Page

In article , (Clive Page)
wrote:

On 07/01/2016 23:45, Dr J R Stockton wrote:

A select portion of central Cambridge still used 110 volt
(approximately) lighting in about 1965. I can, if desired, explain
why.

That would be interesting to know.

I went to a shop in Cambridge in 1965 to buy a kettle. I was
surprised to be asked if I wanted it 110 or 230 volt. There must
have been a lot of domestic appliances scrapped at the time of
conversion.

Yet I heard none of this when I arrived in central Cambridge in 1968.

I tried to email John for more details (removing the ".invalid") but it
bounced.

--
Colin Rosenstiel