Dear Bingley: I searched for "orczy Arcades ambo" and got this
http://www.classicreader.com/read.php/sid.1/bookid.1809/sec.9/

A chapter is entitled "Arcades ambo" and appears to refer to two characters, Heron and DeBatz, who are hoping to trap the Scarlet Pimpernel. (Dramatic musical flourish)