The paper by d'Amecourt was published in 1863, yet Liberatore credits d'Amecourt with coining the word some two years earlier. I am no longer thinking that La Conqûete de l'air par l'hélice. Exposé d'un nouveau système d'aviation is the holy grail and that the source is some other correspondence of d'Amecourt's, perhaps with one of his contemporaries or some other worthy. I still feel that the paper has served as a clue of sorts (through Wolf's translation) to getting closer to the truth.