This is to be taken in a double sense. On the one hand, all methods which save on medium of circulation are based upon credit. On the other hand, however, take, for example, a 500-pound note. A gives it to B on a certain day in payment for a bill of exchange; B deposits it on the same day with his banker; the latter discounts a bill of exchange with it on the very same day for C; C pays it to his bank, the bank gives it to the bill-broker as an advance, etc. The velocity with which the note circulates here, to serve for purchases and payments, is effected by the velocity with which it repeatedly returns to someone in the form of a deposit and passes over to someone else again in the form of a loan. The pure economy in medium of circulation appears most highly developed in the clearing house — in the simple exchange of bills of exchange that are due — and in the preponderant function of money as a means of payment for merely settling balances. But the very existence of these bills of exchange depends in turn on credit, which the industrialists and merchants mutually give one another. If this credit declines, so does the number of bills, particularly long-term ones, and consequently also the effectiveness of this method of balancing accounts. And this economy, which consists in eliminating money from transactions and rests entirely upon the function of money as a means of payment, which in turn is based upon credit, can only be of two kinds (aside from the more or less developed technique in the concentration of these payments): mutual claims, represented by bills of exchange or cheques, are balanced out either by the same banker, who merely transcribes the claim from the account of one to that of another, or by the various bankers among themselves.[11] The concentration of 8 to 40 million bills of exchange in the hands of one bill-broker, such as the firm of Overend, Gurney & Co., was one of the principal means of expanding the scale of such balancing locally. The effectiveness of the medium of circulation is increased through this economy in so far as a smaller quantity of it is required simply to balance accounts. On the other hand the velocity of the money flowing as medium of circulation (by which it is also economised) depends entirely upon the flow of purchases and sales, and on the chain of payments, in so far as they occur successively in money. But credit effects and thereby increases the velocity of circulation. A single piece of money, for instance, can effect only five moves, and remains longer in the hands of each individual as mere medium of circulation without credit mediating — when A, its original owner, buys from B, B from C, C from D, D from E, and E from F, that is, when its transition from one hand to another is due only to actual purchases and sales. But when B deposits the money received in payment from A with his banker and the latter uses it in discounting bills of exchange for C, C in turn buys from D, D deposits it with his banker and the latter lends it to E, who buys from F, then even its velocity as mere medium of circulation (means of purchase) is effected by several credit operations: B's depositing with his banker and the latter's discounting for C, D's depositing with his banker, and the latter's discounting for E; in other words through four credit operations. Without these credit operations, the same piece of money would not have performed five purchases successively in the given period of time. The fact that it changed bands without mediation of actual sales and purchases, through depositing and discounting, has here accelerated its change of hands in the series of actual transactions.