Cornish beam engines - understand continued use

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Total digression, but...
Are you able to explain? A Mustang over eg. Berlin has to have enough fuel to get home - several hours flying. Yes it's emptied its drop-tanks, but its wing tanks are full to the brim (?) I meets the then Luftwaffe planes which are on a splash-and-dash. How come the Mustangs prevailed? Is it that they only had to "tie-down" (fully occupy) the German fighters? Leaving the bombers to do their work?
Reply to
Richard Smith
Total digression, but...
Are you able to explain? A Mustang over eg. Berlin has to have enough fuel to get home - several hours flying. Yes it's emptied its drop-tanks, but its wing tanks are full to the brim (?) I meets the then Luftwaffe planes which are on a splash-and-dash. How come the Mustangs prevailed? Is it that they only had to "tie-down" (fully occupy) the German fighters? Leaving the bombers to do their work?
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During the Luftwaffe debates on rec.aviation.military I concentrated on technology and left tactics and organization to British expert Keith Willshaw. He's still active in the group and may know something about welding. snipped-for-privacy@gmail.com
Reply to
Jim Wilkins
If you haven't found them yet... you should check out the Shay Locomotives ;-)
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We have one locally:
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Maximum Safe Speed: 17.2
Reply to
Jim Wilkins
for what it's worth - the "duty" as keenly measured in Cornwall (UK) from 1800-ish to 1910-ish ft-lb of work done per bushel of coal (either 94lb or 100lb of coal - not "got to the bottom of that").
How is the work done measured or estimated for a pumping engine keeping a mine clear of water? I found the answer in On the Steam Engine In Cornwall Thomas Lean 1839 (reprint from the late 1960's)
I've previously calculated for a "duty" of 100million 10.6% thermal efficiency if 94lb of coal per bushel 10.0% thermal efficiency if 100lb of coal per bushel
The work done is a close estimate. They know the diameter and stroke of the water pumps. (there's a "lift" over several stages from a mine 100's of metres deep - but water being an incompressible fluid it follows (and is the case that (?)) each pump in the rising sequence has the same diameter, and the stroke certainly is the same, given all pumps are driven by the same pump-rod) So the volume per stroke can be calculated. There is the critism that there may (will be to some extent) leakage past the piston, valves, etc. However, there is good reason for that to be kept minimal. The mine owner doesn't want to pay for coal whose water pumped leaks back to the bottom of the mine. The owners probably also want to know "duty" as accurately as possible to make good business decisions - about the mine at that moment and future equipment acquisitions. So for a combination of reasons, it is "a good bet" to use the swept volume of the pump(s). There was then no good way to measure the rate of water (cu-ft per hour, or whatever) going into the adit from the pump shaft, anticipating that thought / query. So yes, there we have it.
But that 10.6% /
10.0% efficiency - that's the efficiency all the way from coal going into the boiler at the start of the "pumping process" to water spilling into the adit at the end of the "pumping process". It's "the big number overall number which counts". Impressive.
Regards, Rich Smith
Reply to
Richard Smith
There was then no good way to measure the rate of water (cu-ft per hour, or whatever) going into the adit from the pump shaft, anticipating that thought / query. So yes, there we have it.
----------------------- For those who don't know, an Adit is the opposite of an Exit.
If you care enough the flow rate can be measured by timing the filling of a measured volume, perhaps the cistern that stores water for the steam engine boiler. The answer can be as accurate as your timepiece, which can be calibrated within a few seconds per day by determining the local noon (maximum sun height) with a sextant and pan of water.
If you care. Also, how wet is that bushel of coal? As a chemist I would weigh it, bake it dry and weigh it again, then subtract the weight of the ash and clinker afterwards. Those measurements could be done on samples of new coal deliveries, without measuring the water flow.
Thanks to clock and instrument makers length could be measured quite accurately by 1800, we still use the original 1793 French definition of the metre as one ten-millionth of the distance from the equator to the north pole, as registered by marks on a bar, or currently by wavelengths of light. The result was and still is wrong by 0.2mm or two standard hair's widths.
France qualified to set the world standard because they previously had the worst measurement system in Europe, nearly every town was different.
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Accurate measurement has always been a limitation on the advance of science. Experimental uncertainty permitted incorrect alternate explanations like the Sun revolving around the Earth, earth, air, fire and water being the four elements, and the Caloric theory of heat as a physical substance. Without accurate measurement the correct answer was just one of many possibilities. Einstein's Relativity was only a conjecture until measurements of star position displacements during an eclipse confirmed it.
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jsw
Reply to
Jim Wilkins
The water from the mines was is too full of minerals to be much use. It apparently welled-up at quite high temperatures in the 30's or 40's Celsius in the deeper mines. One observation revived now is that the mine water could have a lot of lithium in it - and effort is being made to "mine" lithium with boreholes. That added to the reason it discharged down the adit, rather than being brought to surface. I'm finding many mine depths being "below adit" rather than "below surface".
For the mining, leats were constructed to bring water. Devon and Cornwall are very green - for good reason - it rains frequently. For the boilers and condensers yes, but also for the mineral dressing. Apparently where there was a shortage of water and they had to bring mine water to the surface and use that, boilers only lasted a couple of years, or something like that.
Reply to
Richard Smith
The water from the mines was is too full of minerals to be much use...
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It was technically possible for them to measure flow rate though probably not worth the effort if the results wouldn't lead to cost-effective improvements.
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"Due to the limitations of technology and economy up to and during the 1950s, only Orifice plate flow meters were being used in all industries, including the rotate flow and pilot tube."
Ancient Roman water meters weren't much different. They installed bronze flow restriction tubes and billed according to their size.
I found some of these second-hand to measure and improve the draft of my wood stove chimney and the air pressure drop (heat transfer rate) through a transistor heatsink.
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The result of my measurements and improvements is burning less than half as much firewood as others with similar houses. They were built with electric heat and though well insulated are difficult and expensive to retrofit with anything beyond a single wood or gas stove in the cellar, so I have a fuel problem similar to Cornwall's. At least I have a 240V 200A electric service able to support any welding or plasma cutting I could want, and a neighbor with undeveloped (hilly) land who let me cut dead trees.
Reply to
Jim Wilkins
"Not worth the effort" is surely the answer. The pump's swept-volume (piston-area x stroke) will give a very accurate estimate of water volume pumped. Measuring water flow directly - at each mine you'd have to get down to the adit carrying your equipment down a small twisting shaft then have some space to deploy it - big "ask". The readings would have to be the same for the same water-flow at each mine - so whatever direct measurement you use would have to be very consistent. Rich Smith
Reply to
Richard Smith
"Not worth the effort" is surely the answer. The pump's swept-volume (piston-area x stroke) will give a very accurate estimate of water volume pumped. Measuring water flow directly - at each mine you'd have to get down to the adit carrying your equipment down a small twisting shaft then have some space to deploy it - big "ask". The readings would have to be the same for the same water-flow at each mine - so whatever direct measurement you use would have to be very consistent. Rich Smith
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Accurate measurement wasn't a priority until recently. Consider that the steam engine had been in use for 150 years before someone bothered to invent the boiler pressure gauge. Previously stokers shoveled in coal until the weighted safety valve opened.
When I was a kid learning to use a lathe the size measurement tool was still friction calipers, set by eye to a wooden ruler.
Reply to
Jim Wilkins
Gee, you must be a really old geezer as, I read, the first hand held micrometer dates back to about 1848
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(:-)
Reply to
John B.
Reading
Historic Steam Boiler Explosions by Alan McEwen (Author) Sledgehammer Engineering Press Limited (Mr McEwen is the friend of a friend)
(title sounds gruesome and in many ways it is, but the insights are notable)
in Boulton&Watt's day, with boiler pressures around 5psi (1/3Bar), the pressure was retained and limited by a water-column of a few feet (very few metres) tall. Over-pressure, and you'd "blow" water and steam into the header tank.
Reply to
Richard Smith
Gee, you must be a really old geezer as, I read, the first hand held micrometer dates back to about 1848
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(:-)
Reply to
Jim Wilkins
Sounds quite a pragmatic start!
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Our Jr High (age 13-14) shop teacher was a retired Swedish cabinet maker who first taught us the old skills like sharpening saws with files and squaring cuts with a plane and try square before introducing us to newer methods. My friends and I were ambitious and competitive enough to try to outdo each other so we learned quite well.
I still use what I learned to make press-fit joints in timber framed woodsheds at the back end of my property, beyond the reach of electricity, and have even used them for hand fitting parts in electronic equipment, including a prototype of the Segway balance sensor.
Reply to
Jim Wilkins

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