Trade-Specific Measurements: Every Craft Its Own Ruler
Medieval and early modern societies developed incredibly specialized measurement systems tailored to specific trades and crafts. Each profession created units optimized for their particular needs, leading to a bewildering proliferation of specialized measures that often made no sense outside their original contexts.
Cloth merchants developed some of the most elaborate measurement systems in history. The basic ell—roughly equivalent to a yard—varied not just between countries but between different types of fabric. The Flemish ell used for woolens was different from the Flemish ell used for linens. English cloth was measured in ells, but Scottish cloth used different ells, and French cloth used still different ells. International cloth trading required merchants to master dozens of different measurement systems.
More specifically, different types of cloth required different measurement approaches. Heavy woolens were often measured differently than light linens because they draped differently and had different practical uses. Silk merchants used measurements based on the width of silk looms, which varied between regions based on local manufacturing techniques.
The wine trade created equally complex measurement systems. A tun of wine (from which we get the word "ton") was standardized, but different regions filled their tuns with different amounts of wine. The Bordeaux tun was different from the Burgundy tun, which was different from the Rhine tun. Wine merchants needed detailed conversion tables that accounted not just for volume differences but for the different densities of various wines.
Beer measurement was even more complicated. Different types of beer had different densities, and the measurement systems had to account for foam, sediment, and the fact that beer was often sold in containers that weren't completely filled. The English ale gallon was different from the wine gallon, and both were different from the corn gallon used for measuring grain.
Construction trades developed measurements based on their materials and techniques. Bricklayers measured in courses—horizontal layers of bricks—and developed conversion systems between courses and standard length measurements that accounted for mortar thickness and brick sizes. Stone masons used measurements based on the sizes of stones they commonly worked with, leading to units that varied significantly between regions depending on local stone types.
Carpenters created measurement systems around lumber sizes and joinery techniques. The carpenter's foot was often different from the standard foot because it was divided into inches that worked well with common lumber dimensions. Timber merchants used measurements based on tree sizes and wood-cutting practices, leading to units like the cord (still used for firewood) and the board foot (still used in lumber sales).
Metalworkers developed measurements around the properties of different metals. Gold and silver were measured using systems that accounted for purity as well as weight, leading to complex units that combined mass and quality measurements. Iron and steel measurements reflected the realities of metalworking techniques, with units based on the sizes of ingots, bars, and sheets that were practical to work with.
Maritime trades created measurements adapted to shipbuilding and navigation. The fathom, originally based on arm span, was standardized for measuring water depth and rope length. Ship measurements used units based on typical vessel dimensions and sailing requirements. Maritime distance measurements like the league varied depending on whether they were used for coastal navigation, open-ocean sailing, or port activities.
Even more specialized trades had their own measurement systems. Goldsmiths used measurements based on the sizes of precious stones and the properties of gold alloys. Glassmakers measured using units adapted to glassblowing techniques and furnace sizes. Printers developed measurements around type sizes and paper dimensions that persisted well into the digital age.
These trade-specific systems weren't just arbitrary complications—they encoded centuries of practical experience and professional knowledge. When a carpenter used carpenter's measurements, they were employing a system optimized for their specific work requirements. The complexity arose when different trades needed to interact or when societies attempted to impose unified measurement systems across multiple professions.