The convenience of this method being found great, it was improved as commerce increased, till a market was established where merchants might meet and make their exchanges without loss of time, instead of having to run after one another in search of what each wanted. The next thing was to institute a class of persons whose express business should be to manage these transactions. These persons, the bill-brokers, can tell how nearly the debts of different countries balance each other; and it is they who first purchase, and then provide merchants with these acknowledgments of debt, which circulate instead of money. These disposable acknowledgments, called bills of exchange, bear a very small proportion to the bargains between any two trading countries; because, where there is considerable intercourse, the sales of one party generally nearly balance those of the other. The nearness of their approach to a balance determines the price of those bills which remain to be sold, or which are desired to be bought. When bills are scarce, and merchants have difficulty in procuring these ready means of discharging their debts, they are anxious to pay a price for them, in order to be spared the inconvenience of transmitting money. A competition ensues, and it becomes generally known that the country where the bills are scarce has bought more than it has sold; that it owes more money than it has to receive; that (to use the technical term) the exchange is unfavourable to that country. The reverse is known to be the case when there is a superabundance of bills in the market; so that the merchants of a great trading country anxiously watch the exchange-market, not only to get their own debts settled, but to learn the general condition of commerce.