 Others in the second half of the sixteenth century, notably Navarrus, Luis de Molina, and Jean Bodin, arrived independently at a variant of the quantity theory of money. A century later, John Locke and William Petty added two additional variables, the velocity and the transactions level, to the core relation in the quantity theory of money. The velocity of money is something of a misnomer. It is the average rate at which a given unit of currency turns over in a given period of time. The transactions level is the rate at which payments are made, for example wages (daily or weekly) or rents (quarterly). For the capital bill, Petty estimated that five per cent of its value was manifest in liquid terms at any point of the year, a sum equivalent to the interest payment. As a remedy for the shortage of money, a problem that beset not only Petty’s Ireland but virtually every nation, the best policy was to shorten the temporal interval for the transactions level and hence increase the velocity. These four variables were cemented by Irving Fisher in 1911, with his equation that MV = PT (money supply (M) times the velocity of money (V) is equal to the price level (P) times the transactions level (T)). Fisher was also the first to measure the velocity of money. The average rate for the turnover of one dollar in New Haven was twenty times per annum.