History of Measurement
Length, Weight, & Capacity
Some of the Contributors
Elizabeth the First
Although weight cannot be as reliable as length in referring to the human body, people did use similar methods in setting standard weights. Like iron poles were kept in the temple to set a standard length, a lump of metal could also be used to act as a standard. Because grains remained fairly the same weight, the lump of metal would equal a certain number of grains. This piece of metal could be used in a balance to compare its weight to the weight of other objects. To compare weights, people created a balance scale. This dates back to 2000 B.C., where those living on the Indus River used two plates and a center pole to weight objects and set them to equilibrium if desired. This method of weighing lasted through the late 18th century, until Richard Salter created the spring scale in 1770.
Capacity oftentimes relied on weight when exact amounts needed to be determined. Approximate consistent sizes of baskets and jars could be made in order to store things for many everyday transactions. The terms that we currently associate with capacity, such as liter and gallon, actually arrive from weights. People would relate the weight of a liquid to a certain number and call it a gallon. In the U.S., we know that a gallon weighs 8.34 pounds when at room temperature. This same idea is how people from as early as 200 identified amounts of liquid. Although this method has been used for centuries, it wasn't until the late 20th century in which the Standard Imperial Gallon was created in order to provide a world-wide standard, which stated that the weight of one gallon equals 8.6 pounds. This is a part of the metric system.