There is no part of our banking machinery which has received so little elucidation as that of the domestic exchanges. Even for normal times the subject is obscure, and the writer therefore ventures upon an explanation of its course during a period of crisis with hesitation, and he is by no means confident that important considerations may not have been overlooked. As in the case of foreign exchange, domestic exchange rates fluctuate within limits fixed by the cost of shipping money, and also, in the case of cities distant from New York, by the loss of interest while currency is in transit. The quoted rates apply principally to business between banks, the rates being determined by demand and supply. A Boston bank, for example, receives from its customers New York drafts and also checks drawn on banks in New York and its vicinity. All these items will serve to build up its balances in that city. On the other hand, its depositors have been sending out checks, many of which will in the course of time reach New York and reduce its balances there. The Boston bank will also have received from banks of New York and from banks elsewhere items for collection in its vicinity, and remittance in ordinary course will be made by it in New York funds. Similarly it has sent away items for collection to banks in other cities upon which it expects a like remittance. As a result of all these various influences the balances of the Boston bank may either increase or decrease. If they increase it may be ready to sell exchange to other Boston banks whose balances are running low. It may also happen that the bank is desirous of reducing its New York balances, and in that case it will also appear as a seller of exchange in the market. Now, if in the course of a crisis clearing-house loan certificates become the principal or sole medium of payment between banks, it may well happen that a bank will be unwilling to sell exchange unless it is unusually well supplied with New York funds. By the sale of exchange it can at best only secure a favorable clearing-house balance, which will be settled in loan certificates, and if this balance should be unfavorable it can meet it by taking out certificates on its own account. Each bank, therefore, to a greater extent than in normal times, is obliged to rely upon itself for means of payment in New York. The loan certificate does indeed yield a return or involve an expense of 6 or 7 per cent., while the return on New York balances is only 2 per cent. This advantage does not, however, seem to have induced the banks to sell exchange as freely as in normal times.