Ari Belenkiy

Norms of coining at the Royal Mint and Newton’s revolution

Producing coins at the Royal Mint included ten quite diverse operations supervised by the Master of the Royal Mint. The norms, known as the Master’s remedies in shear and assay, initially introduced in mid-13th century by King Edward I, were to check on the Master’s overall performance, i.e., ensure that the coins conformed to the standard weight and fineness within a certain error margin.
From the very beginning, the remedies were set unreasonably wide, in part, due to inability to control the variations in a coin’s weight and fineness. This situation, in the end of the 17th century, led to the pernicious practice by English bankers and goldsmiths of culling the heavy guineas and gaining profit from melting them to strike lighter weight coins.
However, in 1719, Sir Isaac Newton, then the Master of the Royal Mint, in a letter to the Treasury claimed to have stopped the practice of culling in Great Britain thus “saving some thousands of pounds to the Crown.” By examining Newton’s archive and the statistical data from the Jury Verdicts from the trials of the Pyx, held during Newton’s tenure at the Royal Mint (1696-1727), we speculate on what improvements he could have achieved in coining and estimate of how many “thousands of pounds” he saved the Crown.
Next we introduce the variation in weight of a country’s major gold coin, a quarter of ounce, as a new measure of the technological level of a country. We trace this parameter for several epochs from 1663 to the modern times and discuss its limitations.

Ari Belenkiy, “The Master at the Royal Mint: How much money did Newton save Britain?” (Journal of the Royal Statistical Society: Series A, 176 (2), 2013, 481-498).

Key words: Royal Mint, Isaac Newton, the guinea, trials of the Pyx, Jury Verdicts, remedies in shear and assay, margin, practice of culling, normal distribution, standard deviation, small samples, the Law of Large Numbers