Talk:Cornish engine

Winching mine workers?

Could sombody tell me how you "winch miners workers and materials into and out of the mine" with a steam pumping engine? I think it is time to better define whether we mean by "Cornish engine" an engine working on the [[|steam engine|Cornish principle]] (the normal usage as far as I can see) or just any type of engine built in Cornwall.--John of Paris 09:21, 16 April 2007 (UTC)

At the risk of making suggestions along the lines of grandmothers and egg-sucking, were you aware of the man engine article?

But I agree with your question...this article is not exactly clear in this respect (or most others!!) and needs clarifying. Unfortunately, if colloquial usage is confused, then we are probably on a losing battle.

EdJogg 09:59, 16 April 2007 (UTC)

(PS - recommend the Cruquius link - the animations are exceptional)

Ah, you've caught me napping there me there! Never heard of the man engine - an egg this grandma has never sucked. As for the Cruquius engine, I visited their site a long time ago - you're right, it's magnificent - pity it no longer works by steam. Anyway, see you back here in a week or two--John of Paris 18:07, 16 April 2007 (UTC)

A so called "Man Engine" works on the exact same principal as a pumping engine, except that in Cornish usage, the term refers more to the pitwork and line of rods descending the shaft, rather than just the engine itself. To a Victorian Cornishman, an "engine" is any device that does work, powered or not, so the name applies to the whole assembly, there is no specific type of Cornish engine to do this work. In actual fact, the engines themselves were most often Cornish cycle rotary engines, the same as a winding engine, often brought second hand from a mine that used it to wind ore, and was set to run at a constant speed without much supervision, and with no need for the engine driver to hold the regulator - the rotary motion was converted into a reciprocating up down motion by a lever known as a balance bob, to the end of which was attached the line of rods. I will take a look at the article and see what I can add to make it a bit clearer. --▫Bad▫harlick♠ 23:28, 21 October 2009 (UTC)

I think the wording currently used in the article reflects your understanding: the Cornish engine drove a man engine, rather than being a special type of engine. It might be appropriate for you modify that article to describe the steam engines used as the power source, rather than change text here.

I am curious that you mention 'rotary'. The current article suggests that they were reciprocating beam engines, not rotative types (which came later, surely?)

EdJogg (talk) 23:49, 21 October 2009 (UTC)

It was my understanding that a man engine was a device by which miners could ascend or descend into a mine without spending a lot of time and energy climbunbg ladders at each one of the day. I would be powered by a steam engine, probably usually a Cornish engine (though not necessarily - this is a species of engine, not primarily concerned with geographic area), but the man engine itslef was not a steam engine. Peterkingiron (talk) 19:59, 22 October 2009 (UTC)

Removed word

I have removed the word "sough" from the article, and replaced it with "adit". They are basically the same thing, however "sough" is a colloquial term specific to the Derbyshire lead mining district that never made it to mainstream modern mining terminology. Adit is more universal and is the standard term in Cornwall.--▫Bad▫harlick♠ 23:28, 21 October 2009 (UTC)

To my mind they are not synonyms: a sough is a drainage level; an adit is a horizontal access route. The term is perhaps most evident in Derbyshire, but by no measn confined to it, for example it was used in Black Country coal mining befoire 1600. Peterkingiron (talk) 20:03, 22 October 2009 (UTC)

Cornish engine vs. Cornish steam engine

The page has recently been moved from "Cornish engine" to "Cornish steam engine" - I think this was a mistake. A Cornish engine is a particular type of steam engine, while a "Cornish steam engine" could be any steam engine of any type used or built in Cornwall. Your thoughts? DuncanHill (talk) 11:35, 5 May 2010 (UTC)

I'm happy with the move. "Cornish engine" could equally be any petrol engine built or used in Cornwall. "Cornish steam engine" is somewhat superfluous amongst the cognoscenti, but an encyclopedia should be accomodating of its readers and "Cornish steam engine" is both a little more accessible, and still perfectly accurate. Andy Dingley (talk) 11:40, 5 May 2010 (UTC)

I came here to make the same point as DH. I don't think that the page move actually helps with the existing problem of distinguishing Cornish-type engines from Cornish-built engines; and if "Cornish engine" is the usual name, that should be the article name (by WP convention). However, provided it doesn't encourage editors to change article text to match, I guess the page move OK. -- EdJogg (talk) 12:21, 5 May 2010 (UTC)

Neither form of name distinguishes between -type and -built (or -installed).
Is there any situation where "Cornish steam engine" is demonstrably less clear?

"Cornish engines" aren't well-known. It's not clear amongst people who know that they're steam engines what makes them different. It's certainly not self-evident to a general population that they're steam engines. Andy Dingley (talk) 12:46, 5 May 2010 (UTC)

I didn't thing about this when I implemented the move; however as stated above, I also feel that this is a problem which already existed with the original name (Cornish engine); the move to Cornish steam engine doesn't exercebate this problem. I think that a solution could be to simply use the name of it's inventor instead; the article here makes it sound like that's also Watt, but actually it isn't; its Trevithick; see History_of_the_steam_engine#The_Cornish_engine_and_compounding; a rename could thus possibly be done to Trevithick steam engine
KVDP (talk) 12:38, 6 May 2010 (UTC)

"Trevithick steam engine" would have three problems:

• They're known as Cornish engines, not Trevithick.
• They post-date Trevithick. He might have originated them, but their development spanned about a century afterwards (last one, at Dorothea Quarry, was 20th century)
• Trevithick invented two engines, and they're importantly distinct both in purpose and in operation.

Andy Dingley (talk) 12:47, 6 May 2010 (UTC)

I hope that the move has left a redirect behind; it certainly should have. I would oppose any "Trevithick engine" becasue he was only one of those whose work led to the fully developed Cornish engine, Arthur Woolf also being important. "Cornish" certainly refers to a type not a location. However the development did take place in Cornwall, because coal was expensive and an engine with a higher duty (lower consumption) was particualrly desirable there. That is also why Cornwall was the "province" on which Boulton and Watt initially concentrated. I am neutral on the article title with a slight preference for moving back. Peterkingiron (talk) 16:01, 8 May 2010 (UTC)

Definition

After reading this article I am still not sure what distinguishes a Cornish engine from other beam engines. Globbet (talk) 21:47, 13 May 2010 (UTC)

It doesn't explain it at all and needs expansion. Try reading Hill's "Power from Steam" if you're in a hurry for it. Andy Dingley (talk) 23:11, 13 May 2010 (UTC)

My understanding is that a "Cornish engine" is one that works on the "Cornish cycle". This means that steam is first admitted above the piston and drives it down (assisted by the vacuum below the piston). As the piston comes up again, the steam goes through a transfer port and fills the lower part of the cylinder. The valve to the condenser then opens, creating a vacuum in the lower part of the cylinder, and the cycle starts again. The steam is therefore used twice - first above the piston to provide pressure and then below the piston to create vacuum. The engine is, however, single acting because both forces are in the same direction. Biscuittin (talk) 20:31, 6 July 2010 (UTC)

Cycle description

Thurston describes the cycle but it is rather difficult to understand and the drawing in Hunter was hard to read. I believe Thurston's diagram in shown in this article, so I will try to use the lettering in the cycle description. If anyone has a good understanding of the cycle I could use help. You can see my attempted description in my undone edit. Hopefully I will be able to do the labeling and confirm the description in a few days.Phmoreno (talk) 01:51, 20 June 2012 (UTC)

Woodall, Frank D. (1975). Steam Engines and Waterwheels. is one of the best and simplest explanations I've seen. I used it for Cataract (beam engine).

"A Cornish engine pumps by a falling weight that is lifted by the engine. " needs expansion. They worked both ways, between early bucket pumps that raised water on the upstroke and the later (as described here) plunger pumps that used the weight of the pump rod on the downstroke. This significantly reduced the upstroke power needed (it was now only lifting the pump rod, not lifting the water and the pump rod) so was a major boost to overall efficiency. Andy Dingley (talk) 07:26, 20 June 2012 (UTC)

Last Cornish engine?

Does anyone know which was the last Cornish engine to be erected? I've got refs for it being both Dorothea Quarry and also Hodbarrow mine, in the Lakes. Both are just into the 20th century. Possibly Dorothea was the last new build, Hodbarrow was the later re-erection of an older engine from elsewhere? Andy Dingley (talk) 07:36, 20 June 2012 (UTC)

Accuracy of recent changes

Per this change https://en.wikipedia.org/w/index.php?title=Cornish_engine&type=revision&diff=724202180&oldid=722386777

Why does it now say, "The principal advance of the Cornish engine was its increase in efficiency due the use of higher temperature steam made possible by a boilers capable of withstanding pressure." ? Rather than the previous, "[...] its increase in efficiency due to expansive working of the steam. "

Firstly this is unclear. An advantage compared to what? Compared to a condensing Watt engine, or compared to a Trevithick high pressure expansive engine? Secondly the added idea (unsourced of course) that the Cornish advantage was from some increased temperature and pressure, when these engines were actually working at lower pressures (and yet greater efficiency) than most contemporaries.

Further issues are the loss of "A Cornish engine pumps by a falling weight that is lifted by the engine." - this was a crucial change contemporary with the Cornish engine, made possible by the switch from bucket pumps to plunger pumps.

Also changing "Trevithick's early "puffer" engines discharged steam into the atmosphere. This differed from the Watt steam engine, which used low pressure steam and so depended in part on the creation of a vacuum when the steam was condensed." to "This differed from the Watt steam engine, which moved the condensing from the cylinder to a condenser separated from the cylinder;" is seriously misleading, as it implies that Watt's changes were to the Trevithick engine, and involved improving Trevithicks's condenser (Trevithick was of course later and non-condensing).

Also change "duty" to efficiency is wrong - far too simplistic, and it also makes no sense when a value of 50 million is still quoted. What's an efficiency of 50 million?

Also, why the change (also at Watt steam engine) from UK to US spelling? Andy Dingley (talk) 20:42, 7 June 2016 (UTC)

The Cornish engine was a compound engine, which is why it was more efficient. This engine was probably developed as a way to boost capacity of an existing Watt or Newcomen engine by adding high pressure engine and reusing it's exhaust or alternately starting with a high pressure engine and adding a Watt engine. The following are my notes from Hunter's Steam Power

In 1830 naval engineers witnessed trials of Cornish engines achieving 6 times the dusy of Boulton and Watt.

Small, horizontal non-condensing engines added as supplementary power connected to the main drive and exhausting to existing low pressure engines (Truchers) “more widely used was adding a vertical high pressure cylinder beneath Cornish engine’s beam, exhausting to the cylinder of an existing Boulton and Watt engine.

Trevithick high pressure engine ran side by side with a Cornish engine for a number of years with equal duty. High pressure engine cost much less.

Some Cornish engines economy was less than 2 pounds of coal per hp-hr and Cornish engines with steam jackets typically used <2.5 lb coal per hp-hr

Phmoreno (talk) 21:34, 7 June 2016 (UTC)

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Pre-developements and history, and Watt and Bulton patents

I believe Jonathan Hornblower around 1781, developed almost the same engine type, but because Watt patented most of the technology in 1778 or so, he couldn't sell it. In 1800 or so patents expired, and in 1804 the Cornish engine was basically a revival of the Hornblower design. 2A02:168:F609:0:5F8:C25A:2F16:ECD5 (talk) 11:42, 26 June 2019 (UTC)