It is impossible in this brief treatise to give more than a suggestion of the various kinds of exchange arbitration being carried on all the time. Experts do not confine their operations to the main centers, nor is three necessarily the largest number of points which figure in transactions of this sort. Elaborate cable codes and a constant use of the wires keep the up-to-date exchange manager in touch with the movement of rates in every part of Europe. If a chance exists to sell a draft on London and then to put the requisite balance there through an arbitration involving Paris, Brussels, and Amsterdam, the chances are that there will be some shrewd manager who will find it out and put through the transaction. Some of the larger banking houses employ men who do little but look for just such opportunities. When times are normal, the margin of profit is small, but in disturbed markets the parities are not nearly so closely maintained and substantial profits are occasionally made. The business, however, is of the most difficult character, requiring not only great shrewdness and judgment but exceptional mechanical facilities. 7. _Dealing in "Futures_" As a means of making--or of losing--money, in the foreign exchange business, the dealing in contracts for the future delivery of exchange has, perhaps, no equal. And yet trading in futures is by no means necessarily speculation. There are at least two broad classes of legitimate operation in which the buying and selling of contracts of exchange for future delivery plays a vital part. Take the case of a banker who has bought and remitted to his foreign correspondent a miscellaneous lot of foreign exchange made up to the extent of one-half, perhaps, of commercial long bills with documents deliverable only on "payment" of the draft. That means that if the whole batch of exchange amounted to £50,000, £25,000 of it might not become an available balance on the other side for a good while after it had arrived there--not until the parties on whom the "payment" bills were drawn chose to pay them off under rebate. The exchange rate, in the meantime, might do almost anything, and the remitting banker might at the end of thirty or forty-five days find himself with a balance abroad on which he could sell his checks only at very low rates.