In the preparation of the following work, it has been my hope, while furnishing a Manual of Political Economy, which should present clearly and intelligibly the leading principles of the science, to afford a full and thorough analysis and description of the different currencies used in the commerce of the world, especially to exhibit the nature and effects of the mixed-currency system of the United States.

Regarding the instruments of exchange as essential, not only to the largest production, but to an equitable distribution and advantageous consumption, of wealth, I have long felt that a work was needed which should give more prominence to the subject of money and currency than it has heretofore received. I have searched in vain for any work on Political Economy, domestic or foreign, which even attempted such a complete view of the monetary question, in all its bearings, as it appears to me to demand. Especially does such a work seem to be called for at the present time, when there are more conflicting views and wider differences of opinion among professors of economic science on this subject, and more popular ignorance and misconception, than on any other. To pass lightly over a matter so important, so interwoven with all the great interests of society, has seemed to me a great wrong to those who, as scholars, are expected to prepare themselves for active duties and responsible positions, and, as citizens, are to decide by their votes the financial policy of the country.

In 1857, I endeavored, in a series of articles upon Political Economy, in the (New York) " Merchants' Magazine," to show the nature and effects of mixed currency, and its practical influence upon trade and industry. This, so far as I know, was the first attempt of the kind. These articles, in connection with other matter appertaining to the same subject, were published in pamphlet form in December of that year.* In 1859, a small but excellent work on Political Economy appeared, from the pen of Professor Bascom, of Williams College, presenting the currency question with great correctness, but with such brevity as not, in my view, fully to meet the wants of the public. Within the present year, and since this work has been mostly in manuscript, a manual has been published by Professor Perry, also of Williams College. It is a work of great merit; the chapter on Foreign Trade being the most able essay upon that subject which has fallen under my observation. The work contains sound views in regard to currency, and a more extended discussion than any that has preceded it; yet it does not give so full analysis as I had already prepared, such as it seems to me one work, at least, should contain.

* Walker on Money and Mixed Currency, 83 pp.

And here I would recognize the earnest and efficient labors of William M. George, of Philadelphia, who published in 1841-2 " A Journal of Banking," and subsequently " A Short History of Paper Money," in both of which he presented an immense array of facts, statistics, and arguments, calculated to awaken inquiry. He was the pioneer in the great work of calling public attention to the effects of such a substitute for money; and his labors are appreciated in this country and Europe, by those acquainted with his writings.

Nor would I fail to acknowledge the valuable services rendered to this department of the science by a profound student and able writer in our public journals, over the signature of " Bullionist," whose untiring efforts have done very much to diffuse correct ideas in regard to the nature of money and currency.

I presume many persons will feel that a larger space has been given to currency than properly belongs to it. To this I can only reply, that nothing is inserted not deemed relevant and essential to a complete understanding of the question at issue, in all its relations. Statistics, facts, and diagrams have been introduced to substantiate the principles announced, and impress their truthfulness.

It may be thought, that too many and too minute details have been given in regard to trade and business affairs ; but experience has shown me, that we cannot safely assume that the students of a college, or the masses of the people, are so well informed in regard to these matters as to make such explanations and illustrations unnecessary.

Another motive that has influenced my mind in the preparation of this volume has been the desire to produce a work especially accessible and useful to business men, merchants, manufacturers, &c. They have a deep and immediate personal interest in all economical questions, and need particularly to be fully informed of the character of that instrumentality by which exchanges are made, and obligations discharged. They are not prepared for the responsibilities and hazards of their several callings, unless they fully comprehend the causes which operate to increase or depress trade, to assure or endanger credit, to expand or contract currency. Political Economy may be considered as emphatically a business science.