We have discussed this topic a lot of times: how the borderline between bm356 and 360 was meant to be, according to the Treaty of 1862, and how it was reconstructed (wrongly, I think) in the 1950-ies. See the previous post and this one.
(the blue line is the proposed new borderline, to my opinion the one meant in 1862)
In the 1950-ies, all borderpillars in this area had disappeared since long, leaving traces in only some rare cases. Thus the locations of almost every bordermarker (they had to be rebuilt) had to be reconstructed by matching the descriptions and distances in the Treaty with the terrain.
Jean Sermet writes in his “Journal de la restauration de l’abornement de la Haute Garonne” (1957) that the location of bm358 was however indisputable (at its current position) but he gives (in this article) no argument for that. If that location was indisputable, it fixes inevitably the locations of bm357 and 359 because the distances in between are described in the Treaty. But as said, he gives in his “Journal” no proof of his assertion.
We all know that Charles Darrieu is an great admirer of Jean Sermet, defending his work and decisions but always by presenting evidence, see his comments at the previous post. In this case, he has found the following phrase of Jean Sermet in the magazine Pyrénées n°131 – JUIL-SEP 1982 p 238: “Il n’y avait pas d’erreur pour le Cap des Entenés et d’autant moins que l’on y retrouva la base de l’ancienne borne 358 de 1863.” So: the remnants of the old bm358 were still present at that time! And that’s a real ‘smoking gun’ in this discussion.
Nowadays, there are no visible traces of a former bm at the location of bm358 but if it was the case in the 1950-ies, it solves and ends this dispute.
But I’m a bit stubborn and in my opinion my hypothesis fits best in the text of the Treaty of 1862. I haven’t found yet old topographic maps of the first half of the twentieth century or earlier. I think they would give the ultimate answer to this question. Or: the discovery of the original bordercross 359.
Thanks to Michel Molia I discovered something amazing: the borderline between bm356 and 357 and between bm408 and 409 will most probably change.
The INSPIRE-project is a broad international attempt to synchronize geodata in the EU. One part consists of re-measuring and re-establishing the borderlines in bilateral agreement. Narrowing down to the ESFR-border: in 2015 an agreement was reached in the bilateral Commission Mixte d’Abornement in Toulouse.
You can see the result for the Pyrenees on this website showing the map with the borderline agreed-upon and the bordermarkers. The main purpose of the project is explained at this page
and specific to the ESFR-border on this webpage.
We read: “Commission mixte 2015. Une ligne frontière unique, bilatérale et numérique a été validée à la CMA de Toulouse en octobre 2015. Mais elle reste temporaire à proximité des bornes non encore mesurées précisément ainsi que de quelques sites où une mise en évidence contradictoire pourrait être produite.” So the newly measured (digitally) borderline is still provisionary because not all bordermarkers have been precisely measured yet.
There are many details still to study and to discuss here but let’s focus on two very interesting areas
Last year I launched a new hypothesis how the borderline between bm356 and 357 was wrongly re-established in the 1950-ies (see this page). So I was happily surprised that the new borderline is exact as I thought it was meant in the Treaty of 1862 . Finally justice.
I was even more surprised – but less happily – by the new borderline on this steep hillside. I have written about its intriguing story on this page. Conclusion then: the treaty leaves no doubt about the right borderline, the placement of four submarkers by Jean Sermet around 1965 served a diplomatic purpose but changed the borderline wrongly. Problem: no one knows nowadays where that new borderline was because 2 of the 4 submarkers are unfindable.
The CMA has aborted the borderline of Jean Sermet but has now its own diplomatic version somewhere in between the (supposed) Sermet-line and the Treaty-line. But it still violates the Treaty! In this case: justice needs to be done yet.
To finish: the map which Michel Molia received from the IGN when he asked for information with some explanation by some IGN-official.
The explanation (added in black on the map) says that the Treaty was inprecise about where the source of the Ruisseau du Terme was. As said that is not true: in my opinion the text of the Treaty leaves no doubt about the course of the borderline.