Wikipedia:Reference desk/Archives/Science/2023 October 12

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October 12

"lost continent"

I have been reading about how the continent of Zealandia has been "lost" for 375 years. I don't know what is meant by "lost." It seems to me in reading various articles that it has only been recently that Zealandia has been determined to actually be a continent, so how was it "lost for 375 years"? Lonewolf19000 (talk) 03:20, 12 October 2023 (UTC)

A "lost continent" doesn't mean everyone forgot about it or didn't know about it, but instead that it no longer really exists. It sounds like it has recently been established that did exist up until 375 years ago, whereas previously it was not known at all. DMacks (talk) 03:24, 12 October 2023 (UTC)

Continents don't disappear over the space of a few centuries. Zealandia subsided over the course of millions of years. AndyTheGrump (talk) 06:15, 12 October 2023 (UTC)

New Zealand was sighted by Abel Tasman in 1642 -- in 2017 that was 375 years ago, is that where that number comes from? --Wrongfilter (talk) 06:41, 12 October 2023 (UTC)

If so, it is a very strange definition of 'lost'. The Māori found it seven hundred or so years earlier. AndyTheGrump (talk) 06:52, 12 October 2023 (UTC)

I know, that was pure numerology. Even so, it would rather have been "lost until 375 years ago". It would be helpful to know where Lonewolf19000 read about this. --Wrongfilter (talk) 06:59, 12 October 2023 (UTC)

Can you give a link to where you read this, so that we can attempt to interpret it in context?  --Lambiam 10:36, 12 October 2023 (UTC)

This was the OP's first edit since 2015, so we can expect an answer to your question in around 3031. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:12, 12 October 2023 (UTC)

It's an easy Google search to find articles that it sounds like Lonewolf19000 might have read. Here's one. I haven't read it yet to see where the number comes from, but should be easy if anyone else wants to. --Trovatore (talk) 22:53, 12 October 2023 (UTC)

For a related discovery, a giant plate tectonics (called by some sites as "ancient continent") locating near the West Pacific Ocean had "lost" for 160 Ma and only until very recently have the small remaining parts been found accidentally.––>(https://www.space.com/scientists-discover-ghost-of-ancient-megaplate) 2402:800:63AD:CB66:D4E:A691:2A3:509 (talk) 14:05, 16 October 2023 (UTC)

Here is an example of the several articles I have come across: https://www.travelandleisureasia.com/global/news/what-we-know-about-zealandia/#:~:text=News-,Zealandia%3A%20What%20We%20Know%20About%20The%208th%20%27Continent%27%20That,Was%20Lost%20For%20375%20Years&text=Concealed%20beneath%20the%20pristine%20waters,Maui%20in%20the%20Maori%20language. 03:21, 13 October 2023 (UTC) — Preceding unsigned comment added by Lonewolf19000 (talk • contribs)

So European explorers, starting with Abel Tasman, had been looking for a hypothetical continent Terra Australis since 1642, near where New Zealand is. When Australia was discovered, much further to the west, it was not thought to be this hypothetical continent, so they kept looking, without success. Some 375 years later it became clear there is a mass of continental crust right there, only, it is a submerged. So the suggestion is that Zealandia, as it is called, is the lost continent.  --Lambiam 05:29, 13 October 2023 (UTC)

Steam engine cylinder size

The article Cunningham Steam Wagon includes the detail The engine was a compound comprising two pairs of high and low-pressure cylinders sized 5 X 3 - 5. Am I right in guessing that means one pair of cylinders 5in × 3in (length × diameter?) and one pair 5in × 5in? Thryduulf (talk) 10:35, 12 October 2023 (UTC)

Difficult to say, the only source mentioned has no details about the wagon. Your guess seems reasonable. Martin of Sheffield (talk) 11:12, 12 October 2023 (UTC)

The Horseless Age Vol. 7 (1900) p. 11 says:

The engine is of the locomotive type, is reversable, and has two pairs of cylinders, each pair consisting of one high and one low-pressure cylinder. The high-pressure cylinders are 3½ inches in diameter and the low-pressure cylinders are 5 inches in diameter, while the stroke is 5 inches for both.

Alansplodge (talk) 11:27, 12 October 2023 (UTC)

Thank you. Thryduulf (talk) 11:35, 12 October 2023 (UTC)

I wish Google gave more than a snippet, that 5-way valve sounds interesting, I assume that "compound to high-pressure..." will be directing high pressure steam to all cylinders for starting/steep hills. What will the next quarter turn do though, perhaps reversing? Martin of Sheffield (talk) 11:41, 12 October 2023 (UTC)

@Martin of Sheffield there is a full view available at [1], which I don't have time to read right now unfortunately. Thryduulf (talk) 11:51, 12 October 2023 (UTC)

It doesn't say anything about a "next quarter turn", just that 1/4 turn of the lever converts from compound to high- pressure or vice versa. In other words, this ia a two-position control. --142.112.221.114 (talk) 12:03, 13 October 2023 (UTC)

In between my wonderings about the valve yesterday and your reply, user Thryduulf pointed me at a full version of the article, not just the Google snippet. The main illustration shows twin eccentrics and from the position and date we can discount gab-gear, so one would assume Stephenson-type valve gear. Unfortunately there is no indication of any roding to control this, so it remains supposition and not suitable for addition to the article. Martin of Sheffield (talk) 13:57, 13 October 2023 (UTC)

{{ec}}Google gave me the whole section on this vehicle (pages 11–16) and although it goes into great detail about some of the mechanisms, it makes no further mention of the specific valve design. Maybe a trip to the patent literature? DMacks (talk) 11:57, 12 October 2023 (UTC)

@Thryduulf: Many thanks. Martin of Sheffield (talk) 12:00, 12 October 2023 (UTC)

I just added another ref to the article, which notes there are indeed a bunch of US patents. But also another interesting detail that power could be selectively applied to front, rear, or both axles. DMacks (talk) 12:12, 12 October 2023 (UTC)

So I was bored and started doodling. A 5-port valve for conversion of two cylinders between compound and parallel operation is not a complicated design requirement. DMacks (talk) 18:30, 13 October 2023 (UTC)