Gunther Schmidt is tracking the traces of the “linkskursiv” roman and italic lettering style, commonly used on maps, for years now. We were in contact a couple of times about this. Via three articles on his blog, he was able to dig up quite some information including this great lettering specimen from the “Musterblätter für topographische Arbeiten des Königlich Preußischen Generalstabs”, 11. edition from 1904.
Check out his post (German) for more wonderful images from this cartography guide.