Dear Tom,
I was aware of course that this was the case, but hoped my query might
elucidate
some more information from areas which haven't been studied extensively (in
Cornwall
for instance). I suspect that there was certainly a lot more in the way of
surface
water leats on Morwell Down, but traces of them only survive in the woods,
and have
been ploughed out on the open Down. I note Ali's comment that some were for
keeping
surface water away from openworks rather than directing it in, so some of
the leats
on top of the Down could have worked in this way, I suppose.
What I was particularly after was evidence for dating of such leats - I seem
to recall
that Phil's Water Hill article in the Transactions of the Devonshire
Association for c.1989
suggested a C17 date for the complex system of leats and reservoirs there,
but am aware
that he may have revised his opinions since then!
There seems to be very little documentary evidence for leats on the Devon
bank of the Tamar
- at least the earliest actual proof of existence of them seems to be
earlier C18, which
of course is really quite recent. Compare the evidence from the Cornish
side, which includes
a 1399 court case concerning a tinner diverting the Cotehele manor mill's
water, and the
existence by 1540 of the long and complex leat system serving Drakewalls
Mine (and probably
many others which these leats passed en route).
Robert
-----Original Message-----
From: mining-history [mailto:[log in to unmask]] On Behalf Of Tom
Greeves
Sent: 28 April 2011 18:00
To: [log in to unmask]
Subject: Re: Leats to openworks
Robert - it's probably true to say that scores of moorland tin openworks on
Dartmoor have leats leading to them, and many have reservoirs associated
with them. I am sure their primary purpose was to assist with removing
overburden and sluicing lighter waste away from working areas in order to
expose potentially orebearing ground. Phil Newman has plotted many of the
leats and reservoirs in his various English Heritage reports and elsewhere.
It would be surprising to find an openwork without a leat or leats leading
to it. Many of the streamworks had similarly complex leats and reservoirs
associated with them. So I would expect your Tamar Valley sites to have
similar features. Some of the leats appear to have collected surface run-off
from hillslopes rather than being tapped from streams or springs.
Tom.
-----Original Message-----
From: mining-history [mailto:[log in to unmask]] On Behalf Of
Robert Waterhouse
Sent: 28 April 2011 11:24
To: [log in to unmask]
Subject: Re: Leats to openworks
Dear Graham,
I'm not sure about chronology - some of our sites have evidence of multiple
workings, as they have different types of extraction pits/trenches, and
several are known to have been worked as early as the mid-C16 (documentary
refs).
I personally suspect they started low down on the steep valley sides where
lodes commonly outcropped at surface, then followed them uphill. The points
the leats arrive at the openworks tend to be relatively high, though that
may have more to do with the most practical points to take the leats from
their source streams.
One of them (the Rubbytown Leat) can be seen in the foreground of the JMW
Turner painting 'Crossing the Brook' in the National Gallery, London.
We have documentary evidence for its existence by the mid-C18 and I suspect
its rather earlier.
Robert
-----Original Message-----
From: mining-history [mailto:[log in to unmask]] On Behalf Of
[log in to unmask]
Sent: 28 April 2011 10:09
To: [log in to unmask]
Subject: Re: Leats to openworks
Looking at alot of open workings on the north Penines especially the
cross fell area there is the classical hushes like Dun Fell but even
the learts leading into these can be very small and also the associated
reservoirs. Other open works do appear to have leats direct from small
streams into them without reservoirs and in other places some of them
do appear to go through small dressing floors before going into the
open work.
The main problem with interpretation is trying to work out a
chronology. did they start working at the bottom upwards top down of
allong the full lenght or in sections?
Graham Brooks
>----Original Message----
>From: [log in to unmask]
>Date: 28/04/2011 9:51
>To: <[log in to unmask]>
>Subj: [mining-history] Leats to openworks
>
>Robert,
>
>Is there any evidence of reservoirs for the water or does it go
directly
>into the openwork? From what you say, there would have been
>insufficient water for significant pumping. While I understand that
>your openworks are not quite the same, our hushes often had lots of
>minor leats running into them.
>
>Regards,
>
>Mike Gill
>
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