Regular communication of news from foreign countries at short intervals became a necessity in the beginning of the seventeenth century. Correspondents were therefore appointed at various important centres, and Englishmen, Hollanders, Germans, Frenchmen and even Italians were induced to enter the Swedish service, before a sufficient number of trained natives could be found for such posts. Out of this institution grew the post-office. As early as the summer of 1620 a regular postal service once a week was established between Hamburg and Stockholm, and other routes were begun. A few years later “the post-office within the country ... was extended ‘to all the provinces’ in the whole kingdom of Sweden.” In 1642–3 the system was re-organized, and Johan Beier, the treasurer of the New Sweden Company, was made postmaster general. Several changes occurred from time to time, but Beier remained in the service until 1654. The postal service was of great importance to Swedish commerce, since the trading companies, merchants and others interested in foreign markets, could now obtain correct and speedy information about prices and the movements of ships. Domestic trade attained large proportions in the seventeenth century. It passed to a great extent from foreigners into the hands of native merchants, complaints even being made that too many people left their farms to become traders; but as late as 1650, however, foreign merchants controlled a goodly share of the city trade. The export and import trade also increased greatly. A considerable percentage of Swedish shipping was in the hands of foreigners, as we have seen; but the government encouraged shipbuilding and the expansion of Swedish commerce through various privileges, reductions of duty on cargoes carried by Swedish vessels and other favors with such gratifying results that the tonnage of the Swedish merchant marine increased over a hundred fold during the years 1611–1660. Swedish ships went to England, Holland, Spain, Portugal, Russia and practically every port in Europe, the Barbadoes, the Canaries and to America and Africa. The principal articles of export were masts, lumber, grain, hides, copper, iron ore, cannon and other implements of war; the incoming cargoes consisted mainly of shoes, clothes, cloth, salt, tobacco and articles of luxury. Drafts were used very extensively. Insurance was also common, and both ships and cargoes were often insured against loss. Goods and ships were bought and sold through agents, who were paid a certain brokerage.