Certainly: “When I [Ellwanger] have been asked to name the best very hardy hybrid perpetual I have given ‘Mme. Boll’, a rose of vigorous growth, luxuriant foliage, and carrying very large flowers of a beautiful carmine rose; the flowers, though of a flat type, are finely formed and very full. Rev. S. Reynolds Hole, in his charming book about Roses, well describes ‘Madame Boll, whose foliage alone, with the dew on it, is worth getting up at sunrise to see, but having flowers to correspond, of an immense size, requisite form, and of a clear bright rose color.’ A few days ago I learned that ‘Mme. Boll’ is a rose of American origin, produced from seed by Daniel Boll of New-York, and sold by him to Mons. Bergeau [sic] of Angers, France, by whom it was sent out in 1859. At that time an American rose would have been considered of no value, while a new French variety would bring a good price.” [Country Gentleman, vol. 45, 1880, p. 86]

I should add that Ellwanger was well positioned to have access to good information on New Yorker Boll, as Ellwanger was a resident of New York and a member of the horticultural society.

Hmmm . . . or did you mean a statement of earlier origination date (I thought you meant a quote earlier than Cochet's)? 1856 is all I find.

And some further speculative thoughts as to chronology: Let's say the 1856 dating has some validity, and that it represents first bloom (but at Boll's, not Boyau's). Boll then growing it for a year and determining that it had value, Boll could have then contacted Boyau and made business arangements such that in 1858 Boll supplied Boyau with ample budwood or newly-rooted cuttings such that, in turn, a year later Boyau would have enough stock to sell. Yes, I can see that succession of events as reasonable. I'd also imagine that Boll prudently kept the original plant and one or two propagations from it "just in case" (rather than to have sent Boyau the original plant, only for it to potentially perish on the way).