Regarding pumping, is the question to depth that could be pumped, or the
volume of water lifted in a given time.
Because the laws of physics always apply.

The torque that can be generated at the water wheel axle is proportional to
the dia of the wheel, & the weight of water in the buckets (width of the
water wheel).
A small dia wheel using a large volume of water will produce similar power
to a larger dia wheel with narrower buckets (using a smaller volume of water
to drive it )

It all comes down to foot/pounds per min (good old imperial units)
This is why where circumstances provided a large flow of water small / wide
wheels could be used, but if the water supply to drive the wheel was
limited, larger dia wheels had to be used to achieve the same power output.
This often required the construction of long leats to bring the water to the
wheel at the required height.

The Cornish pitwork was inherently inefficient, but the lift of the bottom
bucket lift is again limited by the laws of physics (a column of water that
can be supported by a perfect vacuum.......due to the atmospheric
pressure ).
The bottom lift with its leather cup washer & clack would not have been
perfect, together with grit & small stones getting sucked in through the
wind-bore. So a typical lift (below the bucket) for a bucket lift would be
20 to 25 feet, but the column of water above the bucket could be
considerable before discharging into the cistern of the first set of plunger
pole lifts.

The height of water above the bucket would be limited by the strength of the
wrought iron rods that attached it to the timber pump rod.

The reasons that a bucket lift was used for the bottom lift was to enable
the shaft to be deepened & the pump extended by simply bolting in an extra
length of pipe & a longer rod. Also in the case of a malfunction of the
clack (even if the sump got flooded), the bucket (& its clack) could be
drawn up through the pipe to be repaired / replaced).

Regarding the lift of the plunger pole lifts, this again is proportional to
the dia of the "plunger pole" & the length of stroke, together with the
weight of the shaft pitwork to force the water up the shaft rising main to
the next lift of plunger pole.  Each cistern collecting water from the
higher levels, so the volume of water to be lifter often increased as one
got closer to the adit level.

Hope this is of help. Reply off list for more details of pumping / pumping
power / capacities etc.

Regards, Bob.


----- Original Message -----
From: "Rick Stewart" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, 5 April 2003 05:15
Subject: Re: Pumping


> Mike
>
> Thanks for the reply.  In using the term "Cornish pitwork" I refer to a
lift
> of plunger pole pumps with  a bucket or lift pump at the bottom.  As far
as
> I know (and I may well be wrong) this arrangement originated in Cornwall:
>
> The first use of a plunger lift in Cornwall would seem to have been at Ale
&
> Cakes in 1796. Ref: Mining Journal Nov 5, 1859, p.775.
>
> Also
>
> "About 1806, however, Captain Joel Lean, the manager of Crenver and
Oatfield
> Mines, substitited a plunger in place of the bucket - pump with a view
> merely to lessening the wear and tear on the pumps.....  This alteration
was
> found so advantageous that it was ultimately brought into general use, the
> whole of the pumps in the shaft being made of the plunger description,
> except for the bottom one, which for various reasons is still a lifting
> pump." Ref:  Hamilton Jenkin A.K (1927), The Cornish Miner.
>
> As to the use of the "Cornish"prefix:
>
> "The Cornish pump, now obsolete, which was......" Ref:  Higham S.(1951),
An
> Introduction to metalliferous mining, Charles Griffen & Co. p.234.
>
> Rick
>
>
> ----- Original Message -----
> From: "Mike Gill" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, April 04, 2003 1:12 PM
> Subject: Pumping
>
>
> > Rick,
> >
> > According to William Pryce (pages151f), a 48 foot diameter wheel at
Cooks
> > Kitchen Mine was pumping from 80 fathoms under the adit (using four
lifts
> of
> > 9 inch pumps).  He claims that if there had been enough water, it would
> draw
> > from 40 fathoms deeper.  That was around 1778.
> >
> > I would question your ascription of the tag 'Cornish' to the pitwork.
> What
> > was particularly Cornish about it?
> >
> > Mike Gill
>