First of all he has a bank, into which he pays day by day the fees that
he receives in coin or notes and the cheques that he gets, each half
year, from those of his patients who have an account with him. As long
as his money is in the bank, the bank has the use of it, and not much of
it is likely to go abroad. For the banks use most of the funds
entrusted to them in investments in home securities, or in loans and
advances to home customers. Part of them they use in buying bills of
exchange drawn on London houses by merchants and financiers all over the
world, so that even when he pays money into his bank it is possible that
our doctor is already forming part of the machinery of international
finance and involving us in the need for an explanation of one of its
mysteries.

A bill of exchange is an order to pay. When a merchant in Argentina
sells wheat to an English buyer, he draws a bill on the buyer (or some
bank or firm in England whom the buyer instructs him to draw on),
saying, "Pay to me" (or anybody else whom he may name) "the sum of so
many pounds." This bill, if it is drawn on a firm or company of well
known standing, the seller of the wheat can immediately dispose of, and
so has got payment for his goods. Usually the bill is made payable two
or three, or sometimes six months after sight, that is after it has been
received by the firm on which it is drawn, and "accepted" by it, that is
signed across the front to show that the firm drawn on will pay the
bill when it falls due. These bills of exchange, when thus accepted, are
promises to pay entered into by firms of first-rate standing, and are
held as investments by English banks. Bills of exchange are also drawn
on English houses to finance trade transactions between foreign
countries, and also as a means of borrowing money from England. When
they are drawn on behalf of English customers, the credit given is given
at home, but as it is (almost always) given in connection with