I read up on the beasts and then took the plunge and bought a Tenor on eBay for a reasonable sum, advertised as a "Caravelle, Brittany," vintage, the only references I could find on the Web were those left in Forums by the vendor who as obviously just as keen to find out about it as I was. It looked good so I bought it anyway.
When I got hands on so to speak it became obvious that the Caravelle name had been put in by Engineers stamp to the right rear of the Bell (about 4 o-clock looking down in the playing position), I think this is no more than an owners mark, a Hotel or Cruise Ship band instrument maybe. BUT - what is it?
On one site I found a reference to a distinctive Dolnet engraving which seemed to be inspired by the graphic illustration of magnetic fields using a bar magnet, a sheet of paper and some iron filings and I thought WOW! Subsequent searches led me to your Dolnet section, hence my e-mail.
My Tenor certainly has an engraving similar to that, it has mother of pearl buttons on the keyguards, but they resemble Alto one piece keyguards rather than the separate Tenors guards.It had been covered with gold lacquer which had been crudely removed except for some hard to get at bits, and looked as though it had been 'scraped' instead of dissolved.
The mechanics seem sound if a little stiff, needs a bit of oil and some loving care, there is no perceptible axial movement in the supports and only the slightest 'tick' end to end which I would suggest is no more than reasonable clearance, the end pin screws show no signs of use or abuse. (I do have experience in engineering). Either it has had little use or has undergone a professional service during its life.