Metrication - Forerunners of The Metric System

Forerunners of The Metric System

Decimal numbers are an essential part of the metric system, with only one base unit and multiples created on the decimal base, the figures remain the same, simplifying calculation. Although the Indians used decimal numbers for mathematical computations, it was Simon Stevin who in 1585 first advocated the use of decimal numbers for everyday purposes in his booklet De Thiende (old Dutch for 'the tenth'). He also declared that it would only be a matter of time before decimal numbers were used for currencies and measurements. His notation for decimal fractions was clumsy, but was overcome by the introduction of the decimal point, generally attributed to Bartholomaeus Pitiscus who used this notation in his trigonometrical tables (1595).

In his Essay towards a Real Character and a Philosophical Language, published in 1668, John Wilkins proposed a system of measurement that was very similar in concept to today's metric system. He proposed retaining the second as the basic unit of time and proposed that the length of a pendulum which had a period of one second should be the base unit of length. This length, for which he proposed the name "standard", would have been 994 mm. His base unit of mass, which he proposed calling a "hundred", would have been the mass of a cubic standard of distilled rainwater. The names that he proposed for decimal multiples and subunits of his base units of measure were the names of units of measure that were in use at the time.

In 1670, Gabriel Mouton published a proposal that was in essence similar to Wilkins' proposal, except that his base unit of length would have been 1/1000 of a minute of arc (about 2.04 m) of geographical latitude. He proposed calling this unit the virga. Rather than using different names for each unit of length, he proposed a series of names that had prefixes, rather like the prefixes found in SI.

In 1790, Thomas Jefferson submitted a report to the United States Congress in which he proposed the adoption of a decimal system of coinage and of weights and measures. His proposed base unit of length was the foot which he suggested should be either 3/10 or 1/3 of the length of a pendulum that had a period of one second – that is 3/10 or 1/3 of the "standard" proposed by Wilkins over a century previously. His base unit of mass was to be the bushel, which would have been the mass of a cubic foot of water. Like Wilkins, the names that he proposed for multiples and subunits of his base units of measure were the names of units of measure that were in use at the time.