French patents before circa 1900 are difficult to get hold of. I found that INPI - Institut National de la propriété industrielle - offers facsimiles of old patents (in French: brevets).
So I saw brevets of Clément Ader (1890), Jean le Bris (1857), Louis-Charles Letur (1852) which are related to aviation together with a lot of non-aviation patents.
The total list can be seen
here.
Cheers
Kees