Translations for origin in French

Here are paragraphs from public domain books translated:
This liaison, whose motive and origin were quite unknown, caused a great sensation, for the duke, already known for his immense fortune, now became known for his prodigality. All this was set down to the debauchery of a rich old man, and everything was believed except the truth. The father’s sentiment for Marguerite had, in truth, so pure a cause that anything but a communion of hearts would have seemed to him a kind of incest, and he had never spoken to her a word which his daughter might not have heard. Cette liaison, dont on ne connaissait ni la véritable origine, ni le véritable motif, causa une grande sensation ici, car le duc, connu par sa grande fortune, se faisait connaître maintenant par sa prodigalité. On attribua au libertinage, fréquent chez les vieillards riches, ce rapprochement du vieux duc et de la jeune femme. On supposa tout, excepté ce qui était. Cependant le sentiment de ce père pour Marguerite avait une cause si chaste, que tout autre rapport que des rapports de cœur avec elle lui eût semblé un inceste, et jamais il ne lui avait dit un mot que sa fille n'eût pu entendre.
The Lady with the Camellias, by Alexandre Dumas son La Dame aux Camélias, de Alexandre Dumas fils
"I was not and am not sure which; but I knew that the ship must have an American origin." — Je ne puis pas l’affirmer ; mais je suis sûr de son origine américaine.
The Adventures of Sherlock Holmes, by Arthur Conan Doyle Les Aventures de Sherlock Holmes, de Arthur Conan Doyle