Metrological tables at the end of the 18th century
Abstract
In the eighteenth century and before, the systems of measurement (length, weight, capacity, currencies) are complex. Moreover, they vary from one country to another, from one region to another, from one city to another, from one professional milieu to another. This leads to complicated calculations in everyday life, and multiple opportunities for fraud. To give an idea of this permanent complexity, you can see here the most common units used in Paris before the French Revolution. While mathematical knowledge is increasing strongly in Europe, including the development of calculus, the paradox is that mathematics of everyday life is handicapped by an archaic metrology with intricate subdivisions. Economic agents are prisoners of this complexity. The non-decimal systems used for all sorts of quantities make calculations very exhausting. Only addition is relatively easy to perform. Multiplication and division are nightmares for bankers, traders, notaries, who must calculate interests, rents and shares. Logarithmic tables, which are certainly useful for mathematicians and astronomers, do not work for multiplication in non-decimal systems. Therefore I propose to present some attempts in the late seventeenth and in eighteenth century to facilitate monetary and metrological calculations. We will see how several types of tables were designed in that time, almost by necessity, to facilitate people's everyday life, especially people uneducated in arithmetic.