is used for English feet as well) = 12.789 inches (of English origin). Thus a square arpent was 5299296.0804 in² or about 36,801 ft² or 0.8448 acre. There were many local variations; the metric conversions below apply to the Quebec and Paris definitions. Length ligne – pouce 2.2558 mm pouce – Inch, pied 27.070 mm pied – Foot, varied through times, the Paris pied de roi is 324.84 mm. Used by Coulomb in manuscripts relating to the inverse square law of electrostatic repulsion. Isaac Newton used the "Paris foot" in his Philosophiae Naturalis Principia Mathematica. 1 Roman cubit = 444 mm (so 10000 Roman cubits = 4.44 km, a closer approximation to degree) toise – Fathom, 6 pieds. Originally introduced by Charlemagne in 790, it is now considered to be 1.949 m. arpent – 30 toises or 180 pieds, 58.471 m lieue de poste – Legal league, 2000 toises, 3.898 km lieue metrique – Metric system adaptation, 4.000 km lieue commune – French land league, 4.452 km, Equatorial degree lieue marine – French (late) sea league, 5.556 km, 3 nautical miles. Area arpent – square arpent, 900 square toises, 3419 m2 Volume litron – 0.831018 litres Weight livre – 0.4895 kg quintal – 100 livres, 48.95 kg German system Up to the introduction of the metric system, almost every town in Germany had their own definitions. It is said that by 1810, in Baden alone, there were 112 different Ellen. Length Linie – Line, usually inch, but also . Zoll – Inch, usually foot, but also . Fuss – Foot, varied between 23.51 cm in Wesel and 40.83 cm in Trier. Rheinfuss – Rhine foot, used in the North, 31.387 cm Elle – Ell / cubit, distance between elbow and finger tip. In the North, often 2 feet, In Prussia feet, in the South variable, often feet. The smallest known German elle is 402.8 mm, the longest 811 mm. Klafter – Fathom, usually 6 feet. Regional changes from 1.75 m in Baden to 3 m in Switzerland. Rute – Rod, Roman origin, use as land measure. Very differing definitions, 10, 12, 14, 15, 18 or 20 feet, varied between approx. 3 and 5 m. Wegstunde – 'Way's hour', one hours travel (by foot), used up to the 18th century. In Germany Meile or 3.71 km, in Switzerland 16000 feet or 4.8 km Meile – 'Mile', a German geographische Meile or