The French didn't fully accept Napoleon's metrication in the 19th century: in my 1886 copy of Baedeker's Rhine it explains that, in that book, "Heights are given in English feet (1 Engl. Ft. = 0.3048 metre = 0.938 Parisian ft. = 0.971 Prussian ft)"
Each system subdivided the foot in twelve so the inch, Pouce and Zoll were in the same proportions.