Blockades (see BLOCKADE) may be either on the sea or on land and may be military, naval, or commercial. Most sea blockades are both naval and commercial. The following remarks apply to commercial blockades:

A (commercial) blockade is the investment of the coast or a portion of the coast by a naval force in such a manner as to prevent vessels from entering or leaving any port in the blockaded area without imminent danger of capture. Blockades must be established by proclamation to all states and to the local authorities, and a reasonable time allowed for neutrals to receive the information. Breach of blockade by a neutral merchant vessel renders her liable to capture and condemnation as a lawful prize. But if the vessel escapes to her destination, she is not afterward liable for her act. The cargo of a vessel condemned for breach of blockade is also subject to condemnation. All private vessels, whether belonging to a neutral or the enemy, should be turned over to a prize court for adjudication, but in very exceptional cases they may be destroyed. (Decl. of London, 1909.)

Submarine mines may be laid in any belligerent waters by either belligerent for the purpose of destroying the war vessels of the enemy, but not for the purpose of intercepting commercial shipping, though certain channels to a harbor may be closed by mines, hulks, or any form of obstruction. (Hague Conv., 1907.)

In regard to automatic submarine contact mines The Hague Convention of 1907 provides: "Art. I. It is forbidden:

"1. To lay unanchored automatic contact mines, except when they are so constructed as to become harmless one hour after the person who laid them ceases to control them.

"2. To lay anchored automatic contact mines which do not become harmless as soon as they have broken loose from their moorings.

"3. To use torpedoes which do not become harmless when they have missed their mark.

"Art. II. It is forbidden to lay automatic contact mines off the coast and ports of the enemy, with the sole object of intercepting commercial shipping."

Another article provides that every precaution must be taken for the security of peaceful shipping and to notify neutrals of danger zones when the mines are no longer under surveillance. At the close of hostilities all existing mines must be removed by the state which placed them.

Unneutral Service. Unneutral service includes all acts by a neutral vessel, knowingly performed, which give aid to the enemy or assist him in carrying on the war. These include the carrying of troops or dispatches (not in the ordinary closed mails), or supplies for the enemy; or being in the exclusive employment of the enemy's government; or being under orders or control of an agent placed on board by that government; or taking an active part in the hostilities. Neutral vessels performing any of the services mentioned in the foregoing are therefore liable to capture and condemnation as lawful prizes.

Neutral States during War. It is the right of a state to remain neutral during war. It is its duty to observe that neutrality in its actions affecting belligerents. It is customary for the head of a neutral state to issue a proclamation of neutrality, informing its people of the existVOL. XII.-19

ing war and cautioning them as to the obligations of neutrals and the penalties for breach of such obligations.

Neutral states must not (a) permit the use of their territory by belligerents or (b) aid belligerents in their operations. This aid includes the equipment and construction of vessels of war. But a neutral power is not called upon to prevent the export or transport, on the part of one or other of the belligerents, of arms, munitions of war, or, in general, of anything which can be of use to an army or a fleet. (Decl. of London, 1909.)

The fact of a neutral power resisting, even by force, attempts to violate its neutrality cannot be regarded as a hostile act. (Hague Conv., 1907.)

A neutral power is not called upon to forbid or restrict the use on behalf of the belligerents of telephone or telegraph cables or of wireless telegraph apparatus belonging to it or to companies or private individuals, or even to a belligerent, if erected before the beginning of hostilities and if it is open to all public messages. But a neutral power may restrict the use of these methods of communication provided the restriction is applied impartially to both belligerents. (Hague Conv., 1907.)

The transfer of a merchant vessel to a neutral flag must not be made for the sole purpose of evading capture as an enemy's ship. In order to be valid it must be unconditional, complete, and in conformity with the laws of the countries concerned, and in such manner that neither its control nor the profits of its employment shall remain in the same hands as before the transfer. If the transfer takes place 60 days before the outbreak of hostilities, the transfer is regarded as valid unless it can be proved that it was simply for the purpose of avoiding possible capture. If the vessel lost her belligerent nationality less than 60 days before hostilities began, and if the bill of sale is not on board, her capture gives no right to damages. Transfer to a neutral flag after the outbreak of hostilities is void unless it is proved that the transfer was not made in order to evade the consequences to which an enemy's vessel, as such, is exposed. There is absolute presumption that such transfer is void (1) if the transfer has been made during a voyage or in a blockaded port, or (2) if a right to repurchase or recover the vessel is reserved to the vendor, or (3) if the requirements of the municipal law governing the right to fly the flag under which the vessel is sailing have not been fulfilled. Consult Articles 55 and 56 of the Declaration of London.

Neutral states must not, in the absence of their own legislation to the contrary, permit belligerent war vessels to remain in one of their ports more than 24 hours, except on account of damage or stress of weather. If the war vessel refuses to go, it may be seized and with its officers and crew interned and held until the war is over. (Decl. of London, 1909.)

A belligerent vessel of war may only take, in a neutral port, sufficient supplies of fuel and provisions to enable it to reach a port of its own country. A prize may be brought into a neutral port, on account of unseaworthiness, stress of weather, or want of fuel or provisions, but must leave as soon as the circumstances justifying its entry are at an end. If it does not, and refuses to leave, the neutral power

must seize it, release its officers and crew, and intern the prize crew. (Decl. of London, 1909.)

Airships in War. As regards aviation, airships, and aërial war, no rules of importance have yet received international sanction; but many separate rules have been proposed, and many authorities have written on the subject. The consensus of opinion seems to be that: (a) the air above the territory of a country and of its territorial waters is under the exclusive jurisdiction of that country; (b) the air above neutral territory is neutral and not to be entered by belligerent airships without the consent of the neutral state beneath it, except through stress of weather, injury to machinery, lack of fuel to reach its own territory, etc.; (c) neutral states must not allow their territory or territorial waters to be used by belligerent airships in any manner which may assist their operation; (d) a belligerent state may make such rules as regards neutral aircraft entering its jurisdiction (see rule (a) above) as it may deem necessary for its own protection; (e) belligerent states may exclude neutral airships from the theatre of war to prevent disclosure of their movements to the enemy, whether this be their own territory, that of the enemy, or of a third power; (f) if a neutral airship is engaged in unneutral service, it may be captured if within territory (land or sea) in which such captures can be made and the facts submitted to a prize court for adjudication; (g) in case of capture of a neutral airship engaged in unneutral service its crew may be held as prisoners of war to prevent disclosure (to the enemy) of the information that may have been gained; (h) neutral airships communicating with besieged, invested, or blockaded places are liable to confiscation for breach of blockade, and the crew held as prisoners of war.

By declaration of the Second Hague Conference of 1907 it is prohibited to discharge projectiles and explosives from balloons or by other new methods of a similar nature. But public opinion has changed since that time, and in the great European War of 1914 both sides used aerial craft for bomb-dropping purposes.

It is manifest that airships should carry means of establishing their nationality, and that they should exhibit some distinguishing mark the absence of which would be evidence of unfriendliness; otherwise neutral or friendly airships might be destroyed by their friends.

Bibliography. Henry Wheaton, History of the Law of Nations (New York, 1845); Heffter, Das Europaische Völkerrecht der Gegenwart (Berlin, 1855); Sir R. J. Phillimore, Commen taries upon International Law (3d ed., London, 1879-89); Holtzendorff, Handbuch des Völkerrechts (4 vols., Hamburg, 1885-89; Fr. trans., 1888); T. D. Woolsey, Introduction to the Study of International Law (6th ed., New York, 1891); Sir Travers Twiss, Law of Nations (2d ed., 2 vols., London, 1895-1902); T. A. Walker, Manual of International Law (ib., 1895); Rivier, Principes du droit des gens (2 vols., Paris, 1896); Charles Calvo, Le droit international (5th ed., 6 vols., ib., 1896); James Kent, Commentaries (14th ed., Boston, 1896); Freeman Snow, International Law (ed. by Stockton, Washington, 1898); T. A. Walker, History of the Law of Nations (London, 1899); T. J. Lawrence, Principles of International Law (3d ed., ib., 1900); Henry Wheaton, Elements of International Law (4th Eng. ed. by Atlay,

ib., 1904); Nys, Le droit international (4 vols., Brussels, 1904-06); L. F. L. Oppenheim, International Law (2 vols., London, 1905-06); J. B. Moore, Digest of International Law (8 vols., Washington, 1906); H. W. Halleck, International Law (4th ed., London, 1908); A. P. Higgins, The Hague Peace and Other International Conferences (Cambridge, 1909); Thomas Baty, International Law (London, 1909); W. E. Hall, International Law (6th ed., Oxford, 1910); C. H. Stockton, Manual of International Law (Annapolis, 1911). The most important and comprehensive works are those by Wheaton, Hall, Holtzendorff, Oppenheim, Calvo, Rivier, Heffter, Moore, and Nys. The short treatises by Snow, Stockton, and Woolsey are convenient for ordinary reference. The annual publications of the United States Naval War College and the American Journal of International Law are invaluable for consultation as to recent developments.

The Hague Peace Conference of 1907 and The London Naval Conference of 1909 cover in a general way nearly the whole field of international law as regards war. The Hague Conference adopted a series of conventions on the following-named subjects: (a) pacific settlement of international disputes; (b) respecting the limitations of the employment of force for the recovery of contract debts; (c) relative to the opening of hostilities; (d) respecting the laws and customs of war on land; (e) respecting the rights and duties of neutral powers and persons in case of war on land; (f) relative to the laying of automatic submarine contact mines; (g) respecting bombardment by naval forces in time of war; (h) adaptation to naval warfare of the principles of the Geneva Convention; (i) relative to certain restrictions with regard to the exercise of the right of capture in naval war; (k) concerning the rights and duties of neutral powers in naval war; (1) relative to the status of enemy merchant ships at the outbreak of hostilities; (m) relative to the conversion of merchant ships into warships; (n) relative to the creation of an international prize court. The Conference issued a declaration prohibiting the discharge of projectiles and explosives from balloons (and by inference from all aircraft), and it formulated an opinion and prepared a draft of a convention relative to the creation of a judicial arbitration court. Not all the conventions have been ratified by the Powers, nor were all signed by the delegates of every Power. Convention (k) was not ratified by the United States as regards one article; and conventions (1), (m), and (n) were not signed by the United States delegates and not ratified by the United States. The London Naval Conference of 1909 formulated the so-called "Declaration of London, 1909." This has not been ratified by the United States on account of some of its provisions. Nevertheless, it expresses, with a few exceptions, the generally accepted principles of international law as regards naval war with an authority far beyond that of occasional decisions by judges or of the opinions of the most distinguished international writers. Full reports of these conferences may be found in the annual publications of the United States Naval War College for the years 1907 and 1908; The Hague Conferences of 1899 and 1907 are given by Higgins (see foregoing references) and by James Brown Scott (The Hague Peace Conferences of 1899 and 1907,

law

INTERNATIONAL PEACE MOVEMENT. See PEACE MOVEMENT.

INTERNATIONAL PHOTOGRAPH'IC CHART OF THE HEAVENS. See ASTROPHOTOGRAPHY.

INTERNATIONAL PRISON CONGRESS. The first prison conference was held in 1845 at Frankfort, followed by a second in 1857. These were largely attended by Europeans. After this, local associations were formed, but no international convention held. Count Sollenhub, of Russia, suggested to Dr. E. C. Wines, Secretary of the New York State Board of Charities, that the board call a congress. This was not deemed advisable, but shortly thereafter (1870) the first American prison congress was held, and President Grant was influenced to appoint Dr. Wines commissioner to arrange an international conference. The congress met in London in 1872. Meetings are now held at intervals of five years, the last having been at Washington in 1910. The programmes are arranged by a permanent committee, the International Prison Commission. The scope of the organization is wider than its name would indicate. All matters pertaining to crime and its repression fall within the field of the congress. At present the organization is divided into four sections: (1) criminal law; (2) prison administration; (3) prevention of crime; (4) crime among children and minors. Consult Bulletins and Reports of the

congress.

INTERNATIONAL TRADE. Trade between nations or between distant regions has been a fruitful source of discussion among economic writers, and a subject which has often engrossed governmental attention to the exclusion of internal commerce, though it is a familiar fact that in modern times internal commerce is far more important to the welfare of the state. This apparently undue prominence in discussion and legislation was due not only to the fact that international trade caught the eye of the observer, while domestic trade withdrew itself from observation, but also to the fact that in early economic life foreign trade, as compared with home trade, was far more significant than it is

in modern times.

This greater relative importance of international trade in its historical beginnings was due to the slight division of labor in the older economic order and to the relatively small areas of states. The soil of the neighborhood produced what was necessary for the simple wants of the inhabitants. Towns were rare and small, and artisans few in number. Most of the inhabitants were agriculturists, whose most pressing needs for manufacturing products were satisfied by the produce of the household. In short, the satisfaction of daily wants did not give rise to a "home trade" such as characterizes modern industrial society. To the uniformity of economic organization must be added the difficulty of internal communication as an obstacle to the development of any considerable interchange of commodities. Navigable rivers furnished the only means of internal transportation which were not attended with prohibitive costs. Only those nations with a favorable seacoast could develop any considerable commerce, and with it that diversification

of industrial pursuits upon which domestic trade rests. We may therefore say that foreign trade preceded domestic trade.

If we except the period of the Roman Empire, when such trade as existed became internal trade, because the known world became, as it were, one nation, the division of sovereignty before modern times was so great that most trade was foreign rather than domestic. When petty principalities or provinces of the same realm enjoyed their own customs regulations, much trade was "foreign" which in modern times would be domestic.

Largely to these considerations, as well as to the more showy character of foreign trade, its spectacular and romantic character, does this trade owe its prominence in economic discussion and in the attention of governments. Moreover, as such trade came into early notice as a means of raising revenue for the state, it thus became a matter of public concern.

It cannot be claimed that the contradictory and vacillating practice of medieval rulers developed any well-defined theory of foreign trade. It was not until after the discovery of America and the commercial awakening that followed the influx of the American silver that the beginnings of a theory of trade appear in the writings of pamphleteers who have since been designated as the mercantile school. Thomas Mun, in his work upon England's Treasure by Foreign Trade (1664), states in a few words the wisdom of his time. "The ordinary means to encrease our wealth and treasure is by Forraign Trade, wherein wee must ever observe this rule: to sell more to strangers yearly than wee consume of theirs in value. By such a course the balance must be paid in coin, and the country enriched, while a contrary course would deplete its stock of the precious metals." The confusion of wealth and money is obvious and characterizes the whole thought of the period. As we shall see, it led to some extraordinary governmental measures to promote the flow of gold and silver into the nation and to check its outflow. It distorted the economic policy of the nations for generations and threw the entire public interest in foreign trade upon its capacity to attract specie. It carried with it the corollary that importations should be limited as far as possible and caused vexatious restrictions, high import duties, and frequent prohibitions of the importation of foreign commodities. Thus, in 1674 the total prohibition of the importation of French brandy was advocated in England, not only to encourage the consumption of domestic ale and beer, but also because it was considered undesirable to increase the consumption of French goods. Writings upon trade subjects are full of fears lest any nation should sell more to England than it bought from her, and the government was repeatedly urged to take measures against any nation which so offended against public policy. All writers did not, however, share this shortsighted view, and Mun stands out from his contemporaries by his perception that what is apparently lost by trade with one nation may be the means of gain, since the goods imported from it may be disposed of at great profit to some other nation. He is none the less quite convinced that the aggregate of exports and imports should show a decided balance in favor of the former. Another characteristic of the time is the preference given to trade in distant parts, as when Mun says: "Also wee ought to esteem

and cherish those trades which wee have in remote or far countreys, for besides the encrease of shipping and mariners thereby, the wares also sent thither and received from thence are far more profitable unto the kingdom than by our trades near at hand." The great profits secured by those states which came to be depots of the Indian trade doubtless led Mun to take this view.

To these writers the entire advantage of foreign trade lay in exportation. Importation was at best a necessary evil. So far as individuals were concerned, it is true, the volume of business of both kinds was the measure of profitableness, and traders were prone to encourage all commerce; but from the standpoint of the kingdom as a whole that trade was regarded as profitable which resulted in an importation of specie.

The Physiocrats (q.v.) riddled the pretensions of these writers and held up their policy to derision. Adam Smith demonstrated still more conclusively the weakness of their doctrine. He did not feel it necessary to insist that money and wealth were not synonymous terms, that an increase in the former was not the sole goal of statecraft. In his day England's stock of the precious metals was adequate to its needs and was therefore not an object of peculiar solicitude for the statesman, as it had been in earlier times. Adam Smith states in the following terms the advantages to different countries of international trade: "It carries out that surplus part of the produce of their land and labor for which there is no demand among them, and brings back in return for it something else for which there is a demand. It gives a value to their superfluities, by exchanging them for something else which may satisfy a part of their wants and increase their enjoyments. By means of it the narrowness of the home market does not hinder the division of labor in any particular branch of art or manufacture from being carried to the highest perfection. By opening a more extensive market for whatever part of the produce of their labor may exceed the home consumption, it encourages them to improve its productive powers and to augment its annual produce to the utmost, and thereby to increase the real revenue and wealth of the society." Trade enables a nation not only to obtain what it cannot produce itself, but also to carry its own production to the highest degree of perfection by reason of this outside demand. The advantage of trade lies in its effect upon home industry, and trade is represented as a mutual and not as a one-sided advantage. The home market is now recognized to be the most important, and foreign trade as subsidiary to it, as significant only in so far as it promotes a better division of labor and more productive employment of capital at home. The emphasis is shifted from the purely mercantile side, and the question shown to be a much larger one than a mere increase or decrease of specie.

If the mercantilists insisted that the entire advantage of foreign trade lay in exportation, while Adam Smith deemed the advantage mutual, later writers-as, e.g., John Stuart Mill -have gone so far as to declare that the importance to the nation of its international trade was measured by its imports. This is not, of course, a mere reversal of the mercantilist attitude, for the distinguished economist is far from contemplating the possibility of imports

without corresponding exports. But to him the imports of a nation represent a saving of energy, time, labor, and capital in the acquisition of goods. While the same goods, or many of them, could doubtless be produced at home, it would be at far greater expenditure of effort than that involved in producing the goods exported to pay for them. In following the history of economic thought on the subject of trade, we have passed from the period of a crude but ultra protectionism to one of free trade.

In the meantime new questions have arisen which call for attention. It needs no expert to perceive the advantage of trade between temperate and tropical countries. But in the trade of temperate countries among each other the advantage is not so apparent. It may, and does, happen that a country will import from another a commodity which it can produce at home at less labor cost than is expended upon its production in the country whence it is imported. If such is the case, it is clear that production does not always take place at the point of maximum advantage. It is assumed that within a given country production is carried on at the point of greatest advantage, because of the mobility of capital and labor. But between different nations there is not such perfect mobility, and production continues under varying circumstances of advantage and disadvantage. In domestic trade the costs of production, as a rule, determine prices and values; but in international trade there must be another rule. If England can produce a commodity A with 10 units of productive power, while a foreign country requires 12 units for the same commodity, England may buy of the foreign country, but certainly will not pay 12 units for the goods. The first question which arises is, Why does not England in these circumstances produce the commodity A? Simply because in the production of other commodities, B, C, D, etc., it enjoys still greater advantages over foreign countries. Its maximum productivity is gained by concentration on these other lines of production. In the case mentioned the costs of production for England and the foreign country may be stated as follows for like quantities of each commodity: A. England 10 units, the foreign country 12 units.

It is clear that it will be profitable for England to produce B, C, D for its own wants, and so much in excess thereof as it can persuade the foreign country to take, while it will pay the latter to concentrate its production upon A and supply so far as possible its needs for B, C, and D by importations from England. This shows the motive for an international trade under these circumstances. There is a further question as to the rate at which these articles will be exchanged.

International Values. As in the illustration given it is obvious that England will not pay the foreign country 12 units for A when it can produce A at home for the expenditure of 10 units, the question is how much the foreign country will obtain. If the demand in England for A is equal to the demand of the foreign country for D, the exchange will take place between those commodities. England will get its supply of A at the cost of producing D; the foreign country will get its supply of D at a cost of 12 productive units instead of 15 productive

units. The advantages of the trade are obvious, and the total production of the two countries concerned is greatly increased. If there were no demand in the foreign country for D, but on the other hand a large demand for C, the trade might be between those commodities, and the advantage, though less, might still be considerable. These simple illustrations allow us to state the rule of international value. It is that in international trade the price paid for the foreign article does not follow the costs of production of that article in the country in which it is produced, but rather the costs of production of the article exported in exchange for it. This rule is stated only as a tendency. Economists have devoted considerable attention to the actual equation of exchange. A single modification of the foregoing illustration will indicate the infinite variety of circumstances which modify in practice the tendency stated. Let us suppose that England needs a larger quantity of the commodity A than the foreign country does of D. To stimulate the demand for D, it must be offered at a lower price. So that on the new basis by the exchange of the produce of 11 units of productive power the foreign country gains the same goods as before. Its advantage in the acquisition of D is therefore 15 units - 11 units, or 4 units. On the other hand, England has gained a quantity of A corresponding to the expenditure of 9 units of her own productive power; her gain by the exchange is no longer 3 units, but only 2. In this manner an infinite variety of circumstances, such as cost of carriage, customs, exchange, may be introduced to modify the conditions of the problem.

History of International Trade. It has already been pointed out that the earliest trade was between widely distant nations rather than contiguous ones; that in the entire period which preceded the nineteenth century trade between different countries rested upon a pronounced difference in their products, rather than on such slight advantages of comparative cost as in modern times. Fundamental, moreover, for an understanding of the course of earlier trade is a proper appreciation of the costs of carriage and of the legal obstacles to trade imposed by the governments. These considerations affected in a high degree trade by land, and in lesser measure that by sea and along the navigable rivers.

The great physical contrast upon which early trade was founded was that of temperate and tropical countries, which in historic times was the contrast of West and East. This physical contrast was enhanced by a distinct historical development of the two regions, by the earlier progress of civilization and the arts among the people of the Orient. Hence a large part of the history of commerce is the history of trade with the East. The first trade routes were overland from Central Asia to the Mediterranean, whence the goods were carried by Phoenician and later by Greek traders to all parts of the Mediterranean Sea. In view of the heavy costs of transport, the goods which were so traded were of the richer sort-spices, silk, embroideries, fine linens, and the finer manufactures of the metals-sword blades, gold and silver utensils, and precious stones. To the difficulty of transporting the goods was added the difficulty of protecting them, which again forbade the commerce with bulkier commodities, whose size would be an embarrassment. Protected by the power of Imperial Rome, this commerce extended as far as India and

China, while Egypt was the granary of the Imperial city.

But with the break up of the Roman power commerce declined. Constantinople, indeed, maintained its relations with the East, and at a later period the Arabs, who controlled the southern Mediterranean from Egypt to Spain and had a firm footing in Sicily, carried on a considerable trade. But the Roman civilization on the Rhine, in Britain, and in Gaul, which had brought those countries into close connection with the Oriental world, had been destroyed, while Goths and Lombards subjected Italy to a ruder civilization than it had heretofore known. It was, however, in the Italian peninsula that commerce first arose in the Middle Ages. Venice, Genoa, Pisa, and Florence took up the trade between the East and the West, which in classic times had been in the hands of Greeks and Phonicians. They claimed rights of trade in their settlements at Constantinople first with the Byzantine Empire and later, when Constantinople was taken by the Turks, with the Ottoman Empire. They opened trade with the Moslem monarchies of the Levant and through Egypt reached the trade of India and east Asia. These pretensions were supported by the naval power of the state, which protected the ships of its merchants. They carried the produce of the East and of Italy through the Strait of Gibraltar to Flanders and the Hanseatic towns. At the outset of this new development of maritime commerce it was harassed by pirates, but the strong hand of Venice put down this nefarious practice in the Mediterranean Sea, as the Hanseatic League crushed the Danish sea robbers.

With the advent of the Turks in Asia Minor and the final conquest of Constantinople, the old paths to the East were closed and the supremacy of the Italian states was doomed. New paths were sought to the East-Vasco da Gama discovered the passage to India around the Cape of Good Hope, and in a like quest Columbus revealed to Europe the Western Hemisphere. Portugal, Spain, Holland, England, in turn, succeeded to the commercial leadership. Commerce with these distant lands was not made free to all, but given over to the great commercial companies, of which the East India companies of Great Britain and Holland were the most conspicuous for their enduring results, the Mississippi Company in France and the South Sea Company in England most famous for their spectacular failure.

Of the various restrictions upon and encouragements to foreign trade, which little more than a century ago were so generally in vogue, prohibitive import duties, export duties, and export bounties, one only is of far-reaching significance to-day-duties upon imports. For the various questions to which they gave rise in their modern aspects, see COMMERCE; CUSTOMS DUTIES; FREE TRADE; PROTECTION; TARIFF; MERCANTILISM.

Consult: Adam Smith, Wealth of Nations (2 vols., Edinburgh, 1776; ed. by Edwin Cannan, 2 vols., London, 1904); J. S. Mill, Principles of Political Economy (2 vols., ib., 1848; ed. by Ashley, ib., 1909); J. E. Cairns, Some Leading Principles in Political Economy Newly Expounded (New York, 1900); C. F. Bastable, Theory of International Trade (4th ed., ib., 1903). The subject of international trade is discussed in all textbooks of economics, for a bibliography of which see POLITICAL ECONOMY.