It is for these reasons that the third period 6f world commerce, that of steam, electricity and finance, has been one of unparalleled de velopments. In the first period, extending over thousands of years of the sailing vessel without the compass, in which the oceans were con sidered a barrier to commerce or exploration, the world trade in an entire year was less than that of a single day at the present time. In the second period, that of the sailing vessel and compass, covering about 500 years, in which man traversed the globe by sailing vessels only, he built up world commerce to $1,500,000,000 a year. In the third period, which has covered but 100 years, he has developed a trade of $45,000,000,000 per annum, or 30 times as great as he had been able to create in 3,500 years without the aid of steam, electricity and mod ern finance. International commerce at the beginning of the third period averaged about $2 per capita for the entire world population; in 1913 it was about $24 per capita for the greatly increased population. In this last period of growth the same principles of a division of labor among the people of the earth, the ex change of the products of certain peoples and areas and climates for the different products of other areas and peoples and climates stand out more clearly than in the earlier periods. Manufacturing Europe buys food and manu facturing materials from the other continents and pays for them in manufactures; the United States draws upon the tropics and Orient for manufacturing material and certain foodstuffs and pays for them with the product of her factories; Asia exports her silk and tea and fibres to Europe and the United States and takes manufactures in exchange; South Amer ica and Oceania sell their foodstuffs and raw material to the United States and Europe and take the product of their factories; and Africa sells gold and diamonds and ostrich feathers and high grade cotton and buys manufactures from Europe and America. Everywhere it is
the exchange of the products natural to the area in which they are produced for the natural products of some other area and people, and thus the division of labor becomes more and more sharply defined with the enlargement of transportation, intercommunication and finance.
Bibliography.— Cunningham,