It's fairly frequently that we don't use or mention something that is historically in-period for Fallen London because players would think it's anachronistic. Examples of such things include semi-automatic pistols (definitely a thing you could buy in Europe in 1899). There's one bit in FL where you run into a saxophonist and the only reason that flies is because he's a Devil, and Devils in the FL setting are culturally unstuck in time (even though saxophones had existed for a long time in the period). This phenomenon is a byproduct of the simplified and often incorrect way people conceptualize history.
But one thing that falls under this rule that I am often sad I can't use is the word 'dude' (first attested in English in 1877).
One must look no further than the cavalcade of misfortunes in Adolphe Sax' youth to know that, deep in one's bones.
the introduction is drawn out but important for building up the characters and tension
