Decoding chancery records from the 1240s

The English records from the 1240s contain many references to the purchase of gold on behalf of the king, Henry III. For example, the Liberate Rolls give explicit numerical information about the amounts of gold purchased and the price paid for it. These records also contain implicit information, and this can sometimes be extracted by analysing the arithmetical procedures that were used by the king's officials. We shall see how the purity of the gold was assessed, and how the price varied in consequence. The records occasionally mention gold in the form of coins, and in such cases our method can be used to identify the type of coin involved. Since there is little evidence about the methods used to perform the calculations, we shall consider the extent to which the Hindu-Arabic methods popularized by Leonard of Pisa (Fibonacci) were being adopted in England in the thirteenth century.