Neat! Well, since I did so well on the first guess... He's likely in the album because one of your great-greats met him, or knew him, in some capacity. They undoubtedly admired him and wanted to include the photo as a memento of the great man they had contact with. As for the francais, educated mid-nineteenth century people often 'ornamented' their writings with French phrases, as a sign of sophistication, elegance and education.