In the century or so preceding the industrial revolution, the development of international trade was normal in degree, depend ing mainly on the increase of population and any cheapening in transport caused by improvements in the arts of navigation and shipbuilding. Nations were on the whole self-dependent for the means of livelihood of their people and international commerce consisted of the exchange of surplus products for luxuries from other lands. But with the industrial revolution all this was changed. First England and later other industrial countries became essen tially dependent on external trade. Manufactures were made largely from imported materials and the industrial population tended to depend more and more on imported supplies of food stuffs, both received in exchange for exports of manufactures. International trade increased at a tremendous rate. About the middle of the 19th century a further great stimulus was given to commerce by the cheapening and acceleration of transport through the development of the steamship and the railway.
We have already seen that in 1760 the reputed burden of the vessels belonging to England and Wales was tons. By the year 18co the figure had grown to 1,467,000 tons, in spite of severe losses in the war with France. The tonnage of all ves sels entering and clearing ports of Great Britain from or to for eign countries also increased about fourfold in this period of 40 years. On the other hand the wars practically destroyed the carrying trade of Holland. Reverting for a moment to vessels entering and leaving the Baltic, the numbers passing the Sound in certain years were as given in the table in the next column.
2. Commerce of the United Kingdom, United States, France and Germany to 1913.—In the foregoing sketch of the development of commerce up to the end of the 18th century, the carrying capacity of shipping has been our best guide. With the development of trade in highly manufactured and valuable articles occupying comparatively little space, shipping capacity becomes a less satisfactory measure ; a ton of coal or of iron ore and of cotton piece-goods or machinery have values of quite different orders. About the same time figures of the total value of imports into and exports from the principal trading countries become available and, as late as 188o, about 75 per cent. by value of the goods passing in the trade of world were imports or exports of the United Kingdom, the United States, France and Germany.
In interpreting figures of value the effects of changes in the level of prices must be borne in mind. The following table shows the fluctuations in general prices in the United Kingdom at ten-yearly intervals between 1791 and 1926, as shown by Jevons' index numbers from 1791 to 1846 and Sauerbeck's index numbers from 1846 to 1926. The average of the years 1867-77 is taken as ioo and the two series have been linked on the respec tive index numbers in the year 1846.
1791 . . . . . 107 1871 . . . . . 100 1801 . . . . . 168 1881 . . . . • 85 1811 . . . . . 164 1891 . . . . • 1821 . . . . . 113 1901 . . . . . 70 1831 . . . . . 99 1911 . . . . . 8o 1841 . . . . . 102 1921 . . . • • 1851 75 1926 . . . . . 127 1861 . . . . 98 At the time of the revolutionary and Napoleonic wars prices increased very greatly. After the wars, prices drifted downwards on the whole till about 1850. In the next 25 years they moved up wards reaching a high point (III) in 1873 but dropped back again in the last quarter of the century to some 3o per cent. below the datum line. Prices then increased steadily till the outbreak of the World War. The effect of the war was to increase them very greatly, but since 1920, there has been a substantial fall in the general level, as there was after the wars a century earlier.
(a) The United Kingdom.—A systematic record of the official value of the imports into and exports from England from 1699 to 1778, the same for Great Britain from 1779 to 180o, and for the United Kingdom from 1801 to 1853 is given in Custom Tariffs of the United Kingdom, 1800-1877 (1897). The official values were based on the old valuations laid down at the end of the 17th century. It follows that, while they may afford a basis for es timating the volume of trade from year to year, they give no cor rect idea of the value of the trade of each year at current prices. In 1798, however, an ad valorem convoy duty was imposed on domestic exports and this made it possible to ascertain the real current value of exports. For imports and re-exports, it was not till 1854 that the old official values gave way to current values. Trade with Ireland is excluded from the following figures throughout.
Around the year 17oo the official value of imports into Eng land was about .i5,500,0o0 and that of exports about L6,000,000. During the next 6o years the figures increased slowly but steadily and around 1760 were about i8,50o,000 for imports and £13, 000,000 for exports. From 1760 to 1785 imports continued to grow, exceeding .114,000,00o in the latter year, but exports re mained stationary. In the next 15 years, however, both imports and exports about doubled. From the beginning of the 19th cen tury the figures relate to the United Kingdom and about the same time real values become available for exports of domestic produce and manufactures. In the year 1805, the official value of the imports was £28,561,000 and that of the exports £31,064, 000, of which £23,377,000 represented exports of domestic pro duce and manufacture and the remainder exports of imported merchandise; the real value, however, of the domestic exports was £38,077,000, i.e., about 6o per cent. above the official value.