Talk:Newcomen steam engine

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This article incorporates text from the Encyclopædia Britannica Eleventh Edition, now in the public domain.

Does this page need explanation of how his name was pronounced? (I've heard "noo com un" & "noo cum in") Trekphiler 16:11, 3 December 2005 (UTC)

Maybe on the Thomas Newcomen article, but not here. I pronounce it noo-cum-en, with equal stress on the syllables, but I'm not from that region. User:Noisy | Talk 19:20, 3 December 2005 (UTC)

As I recall, this steam engine was known as the Danemorra Fire and Air Machine. I once read a very old book in the MIT library that referred to it as such, and used the information to build models of the steam engine. They worked like a charm!

JHL, Concord, MA

The engine built by Marten Triewald at Dannemora was indeed an example of the Newcomen engine. Peterkingiron 10:54, 29 November 2006 (UTC)

Contents

[edit] Revision

In revising the article, I have eliminated a number of statements, which seemed to be wrong, not being in accord with the authorative work by Rolt and Allen. I hope that I have avoiding introducing the results of original research. The article as I found it seemed ambiguous as to who invented the jet of water for condensing the steam; I am not sure that the present statement on this is quite correct. If you disasgree with statements that I have made, please argue out the issue here, citing your authority. Peterkingiron 10:54, 29 November 2006 (UTC)

[edit] Animation

I have problems with the animation. The basic principle is clear enough (although it could still be slowed down), however there is no indication as to how the condensed water is drawn off before fresh steam is admitted. — It's spirited away "just like that there"! From contemporary drawings (and the second one in this article) it can be seen that there was a drain pipe from the cylinder bottom leading to a low-level tank (hot well?). Again from contemporary drawings it can be seen that the boiler did not rest on thick brick peripheral walls but on a small ledge which means that hot gases could flow round the sides of the small cylindrical part, consequently the heating surface was greater than just the concave bottom of the "pan" as shown here.--John of Paris 08:50, 8 March 2007 (UTC)

The condensate might run back into the boiler when the value was opened, but most diagrams of engines in Rolt & Allen do have the pipe in question. However they do not make clear whether this was opened automatically at the end of the power stroke, or was opened manually by the engineer when needed. Peterkingiron 21:47, 10 March 2007 (UTC)

My understanding is that the remains of the condensate was driven out through a one-way valve by the action of the admission of the steam. This valve was caled a 'snifter' after the noise that it made. I suspect that it was a simple spring release ball valve, the spring being equal to the steam pressure. Perhaps someone can enlighten us.

--Train guard 15:45, 15 March 2007 (UTC)

Much simpler than you imagine. I visited the Dudley replica on a steam day a couple of weeks ago, but was unable to get a good look at the snifting valve; however I was told it is a simple leather flap closed as you say by steam pressure at admission. You can see in the photo the plugman, Mike Dunn purging the air from the cylinder before starting the engine by the simple expedient of pushing the flap down with a brick. Your "simple spring release ball valve" is simple to make today but far beyond the technical possibilities of 1712. The snifter is the funnel-shaped object soldered onto the lead drain pipe leading from the bottom of the cylinder to the hot well. Above Mike is a fall pipe draining the excess of water used to seal the piston; the small branch leading into the snifting valve provides another water seal with its own overflow also going on down to the hot well. I have put a short report on my recent visits to this and other engines in the talk:steam engine.--John of Paris 09:39, 6 May 2007 (UTC)
Correction Sorry, I may have been wrong about the leather flap. According to David Hulse (see ref. in article), the snifting valve is believed to have taken the form of a conical brass poppet valve maintained in place by its own weight carefully calculated to keep constant steam pressure The snifting valve's job as far as I can gather was to ensure the immediate release of the vacuum on admission of the next charge of steam and to make sure that the cylinder was uniformly filled with steam. This still does not explain Mike's use of the brick that appears to be bearing down on something to release trapped air as he said. I shall enquire further about this.--John of Paris 10:39, 8 May 2007 (UTC)

[edit] Worcester & Savery

I am afraid that the previous description of Savery's engine was factually incorrect and I have just altered it. Referring to [1], there can be no doubt that the engine used alternately both the vacuum effect and steam pressure. As for Worcester, it seems difficult to make out what this engine was actually like: the drawing reproduced by Thurston was copied from that given by Dirk which seems to be the latter's own hypothetical drawing based on Worcester's description. This is worth following up, but would perhaps be more pertinent to the Steam engine article than the present one. Also the statement that Savery introduced the water spray appears to be pure speculation, but I have not touched it yet.--John of Paris 14:08, 5 September 2007 (UTC)


[edit] The view from across the pond

Congratulations, this is an excellent article. I always love those little animations and to me they are what makes on-line encyclopaedias so different from the paper versions. As to the pronunciation of Newcomen, we Brits would pronounce it with equal stress on all the syllables, but of course our pronunciation of "new" is somewhat different from the American one, so we would say nyew-cum-un.The last syllable sounding like "urn" but slightly shorter. I suppose it's like the "en" sound in the American "gotten" Richerman 17:43, 26 September 2007 (UTC)