_Bank business._—Whatever the organization of a bank, its business must be essentially the same. It receives deposits from its customers for safe keeping and for convenience in use by means of checks. A check is simply an order to pay, and, if the receiver is a customer of the bank, amounts to merely a transfer of deposits from one owner to another on the books of the bank. A thousand dollars safely kept in the bank vault may thus change owners a hundred times by means of checks properly recorded. In large transactions the check, because of its economy, takes place of any other form of currency. The bank must also deal in drafts, by which exchanges can be made in different cities, and in bills of exchange, distinguished from ordinary drafts by special reference to foreign trade. It may also hold, as a part of its available machinery, clearing house certificates, which are statements of balances due in the daily settlement between the banks belonging to a clearing house association. All these form a part of the machinery of every-day exchange, and together with a complete system of book-keeping make the utmost facility in the use of money. They also greatly economize in the use of money by saving cost of counting and of transfer, and by securing against losses. If the system offered no more advantages than this safe and ready use of good money, the banks would be practically indispensable. But they have a still greater use in a safe extension of credit. The perfection of system in banking makes it possible for one who habitually fulfils his promises to purchase anywhere in the world on the shortest notice with the simple guaranty of credit in the bank where he does business. A traveler wishing to have funds in safe-keeping, and yet available on a journey around the world, may obtain through a bank familiar with his business standing a letter of credit, upon which he can draw, wherever he may be, against the deposit in his favor, and his draft will be paid, through a series of banks, at the bank near his business connections. Thus the credit of the world is bound together by the banking system grown up to meet the necessities of trade.