SPOILER ALERT: This post is very boring, and mostly pointless: not even flat earthers use this 'proof', and Dubay seems to have gone somewhat out of fashion, but I include it here because: a) I did the research already; b) others debunking his list on their blogs hadn't quite figured this one out; c) it's maybe good that it exists somewhere; and d) it's a great example of how Dubay has compiled, presented, and (not) researched his material. So... At number 13 in his list (video/self-published book/website) of "200 Proofs the Earth is not a Spinning Ball", Dubay says that: As usual, this is a fairly direct quotation from one of the Victorian flat earth texts, this time Samuel Rowbotham's "Earth Not a Globe" (1872): https://books.google.com.mx/books?id=VeBivA6QSEUC&pg=PT47&lpg=PT47&dq=rowbotham+biot+arago&source=bl&ots=2aR3V-9udm&sig=987ij9hMEVA5TGHe_h8H4U2I85o&hl=en&sa=X&ved=0ahUKEwis1Z3Z7bnOAhUG2WMKHbVZDjYQ6AEIKzAD#v=snippet&q="In the account of the trigonometrical operations"&f=false POINT 1: While almost repeated word-for-word, there are a few important changes to note. First of all, Dubay has chosen to call the "trigonometrical operations" a "French experiment" - probably to make it look like a flat earth test rather than the measuring of the globe that it actually was - and, rather than Rowbotham's "nearly the same" elevation of the two points, he has claimed they were "identical." This is a pretty amusing assertion, given neither he nor Rowbotham knew where the points actually were. POINT 2: Another fun one. When reading the text out, he says, "M. M. Biot", as though these were the guy's initials. "MM." actually means "messieurs" - ie, "Misters Biot and Arago." Biot's first name was Jean-Baptiste. TITBIT 1: Biot and Arago were two French physicists, astronomers, and mathematicians - and certainly not flat earthers - who, in 1806, took on the work of measuring the meridian arc which passes through Paris in order to determine the exact length of a metre. It was a pretty Herculean and adventurous task, taking many years and involved scaling mountains, being arrested as spies, and subsequent escapes from the Spanish authorities. Quite the dedication to science! POINT 3: The Desierto de las Palmas is a mountain range in the Spanish province of Castellón. The highest peak is called Bartolo, and it is from here that Biot and Arago made their measurements, as recorded on page 20 of "Memorial du Depot General de la Guerre, Volume 7". The elevations given are between 726.36 metres and 728.29 metres (2383 and 2389 feet). This demonstrates that Rowbotham clearly had no idea of the elevation of the summit of Desierto de las Palmas, since it would be impossible for the two points to be "nearly the same" - the highest point on Ibiza is 1558 feet, and this wasn't the point Biot and Arago were using. TITBIT 2: From "Report of Observations Geodesic, Astronomical, and Physics" by MM. Biot and Arago (1821): https://books.google.com.mx/books?id=3iYyAQAAMAAJ&pg=PA79&lpg=PA79&dq=observations+geodesiques+desierto+de+las+palmas&source=bl&ots=JgkxN7VeTq&sig=2LZulESyPdx7gR085a0GWsfRhqc&hl=en&sa=X&ved=0ahUKEwjcppuFirrOAhVCKGMKHRN8BqsQ6AEIHTAA#v=onepage&q=observations geodesiques desierto de las palmas&f=false POINT 4: While Biot and Arago called the point on Iviza (Ibiza) "Campvey", Dubay copies Rowbotham in calling it "Camprey": presumably because the original publication's "v" looks a little like an "r". Either way, I wasn't able to locate anywhere called Camprey or Campvey on Ibiza now - though, oddly, it shows up on some German sites as an Ibizan peak with an elevation of 396 metres. Handily, this matches the elevation reported by Biot and Arago, on page 9 of the aforementioned "Memorial du Depot" (and elsewhere), making it a good 1090 feet below the summit of Bartolo - ie, not exactly "identical." Using the metabunk curve calculator, and a distance of 100 miles (Rowbotham got that much right) this shows us that at least 224 feet of Campvey should have been visible from Bartolo. Claim #13, therefore, is debunked. FURTHER QUESTIONS 1. Where is Campvey exactly? A topo map of Ibiza locating a peak of 396 metres/1299 feet about 100 miles from Bartolo should do it. Or, in the aforementioned primary sources, latitude and longitude are given for Bartolo as 44.54/+2.56 and Campvey as 43.4/+1.09, but I can't work out what these refer to. Did they have a different system back then? After all, these measurements were taken a good 70 years before the prime meridian was established 2. In the 1870 edition (Volume 7, 4th Series) of "Chambers's Journal of Popular Literature, Science and Arts" the story of Biot and Arago is told, and it's possible this is where Rowbotham took his information, given that he uses the journal in some of his other 'proofs'. The Chambers account seems fairly scientific and straightforward, though, but I can't read all of it, as the digitised google books version isn't available in full-view. 3. Will I do research like this on any more of Dubay's 'proofs'? Hell no! Thorough investigation of this and "#4: Rivers Flow Uphill" (link to metabunk thread) - plus glances at some of the others - has told me pretty much everything I need to know. Hopefully the same can be said for any other sane-thinking person too. Sorry for the tedium!