Talk:Telegraph Plateau

Brooke's sounder
This: Brooke's sounder was designed to release the lead immediately it contacted the bottom, thus preventing more line being pulled out, though referenced, is unconvincing. For a stationary ship, the load on the line would anyway be reduced by the weight of sinker as soon as the sinker was resting on the bottom. For a moving ship, it must be assumed that the line is nevertheless vertical until the sinker strikes the bottom, or else the sounding is invalid. If the sinker then lodged stationary on the bottom, then owing to the great depth, only a minuscule amount of extra line would need to be paid out to allow for the motion of the ship without bearing the weight of the sinker.

Rather it seems that Brooke's sounder allowed for the recovery of the core sampler without the difficulty of hauling in the sinker. The sample if present would confirm that the bottom had been reached, and so would put an upper bound on the depth, without ruling out the possibility that extra line had been paid out. catslash (talk) 00:35, 20 May 2020 (UTC)


 * ...it must be assumed that the line is nevertheless vertical until the sinker strikes the bottom. That is somewhat unlikely in 2000 fathoms (2 miles) of ocean. The ship is going to drift and almost certainly somewhere along that path down strong currents are going to pull the line into a large bow.  The method will undoubtedly overestimate the depth, but nowhere near as badly as without Brooke's lead. SpinningSpark 08:18, 20 May 2020 (UTC)

That is true. However the explanation currently given in the article remains unconvincing, and is at variance with every explanation that I could find. See Rozwadowski catslash (talk) 08:38, 20 May 2020 (UTC)
 * You're beginning to convince me that the article needs amending, but can you read page 78 first before anything gets changed? SpinningSpark 09:09, 20 May 2020 (UTC)

Deep-sea sounding is an unexpectedly fascinating subject -- I'm tempted to buy the book. After reading page 78 and several others, it's clear that a mid-depth current could keep the line taught after the sinker had struck the bottom, and probably more taught than if the sinker was released. Are there any sources that relate this to Brooke's sounder? If not then it's a wiki-sin to imply otherwise. catslash (talk) 10:16, 20 May 2020 (UTC)
 * Yeah, I think you've found a wikisin. I wasn't deliberately drawing my own conclusion, it's just natural, that after the author describes the problem of line runout and then announces a new improved sounder, to run away with the idea that the sounder is to fix the problem.  But on page 79 we have Maury coming up with a completely different solution to the problem – he applies some mathematics to the line velocity (perhaps transmission line theory could have helped him here!) – so maybe the two things really are unconnected. SpinningSpark 10:44, 20 May 2020 (UTC)
 * At least it wasn't in the DYK hook. SpinningSpark 10:45, 20 May 2020 (UTC)

Depth of 6 miles?
The article says that to the south of the plateau the ocean floor sharply drops to a depth of up to 6 miles, but the maximal depth of the Atlantic Ocean is only about 5.2 miles, and that depth is reached near Puerto Rico, which is quite far away from Newfoundland. So, I don't think this statement, even though it is sourced, is true. Spike (talk) 15:14, 25 May 2020 (UTC)
 * This needs rewriting to put it in historical context – the source is from 1858 and they did not have either the accuracy or resolution that we have now. Also, the source does not say the depth drops immediately to the south of TP, but that the bathymetry of the Atlantic to the south is very varied.  That can be clarified as well.  I don't know enough about Brooke's survey to be able to say where exactly he thought these great depths were, but it is not wildly wrong, there are several basins and trenches in the North Atlantic in the 4–6 miles depth range. <b style="background:#FAFAD2;color:#C08000">Spinning</b><b style="color:#4840A0">Spark</b> 17:44, 25 May 2020 (UTC)