A peculiar subset of American exceptionalism is that we measure our vineyards quite differently from the rest of the world, especially the French. The metric system, established by the French Revolutionary government on 18 Germinal, Year III (7 April 1795) is, of course, founded on the meter. One hundred square meters (100m²), the are, is the most basic measure for land, including vineyards, with the hectare (100 ares) being the more common and practical base unit. One hectare equals 10,000 square meters.
The American system of land measurement continues to be based on the acre, (with 2.471 acres equivalent to one hectare). The acre itself is a one of the many units of measure that were standardized by decree of King Edward I in 1300. The acre was supposed to be the quantity of land tillable by a man, aided by an ox, in one day. The traditional acre was described as one furlong in length by one chain in width. (Traditional acres were long and narrow due to the difficulty in turning an ox team and plough). A furlong was the length of a furrow that could be ploughed by a team of oxen before resting. The chain was the equivalent of 4 rods, the rod being the supposed length of an ox goad, the long pole used by the ploughman to motivate his oxen forward. A rod was the equivalent of 5½ yards; and there were 40 rods in one furlong, and 8 furlongs in one mile. An acre, for those still awake and paying attention, was equal to 10 square chains, or to160 square rods.
Prior to the measurement reforms of the French Revolutionary government, vineyards in France were measured by ouvrées and journaux. An ouvrée was reckoned to be the amount of land that a man could manually till in one day; the journal (journaux is the plural) was the amount of land that a man, aided by a horse, could plough in a single day. One journal was comprised of 8 ouvrées; and one ouvrée is equal to 4.285 ares.
If anyone is still following this discourse (if so, we’d love to hear from you!), this question will inevitably arise: since an acre and a journal were both reckoned to be the amount of land that, respectively, an English yeoman and French paysan could plough in one day, why is a journal (at 3424.66 m²) notably less than an acre (4046.95 m²)? Perhaps the French took longer lunch breaks?