the government was allowed to purchase land from Māori, who received cash. The government bought practically all the useful land, then resold it to the New Zealand Company, which promoted immigration, or leased it for sheep runs. The Company resold the best tracts to British settlers; its profits were used to pay the travel of the immigrants from Britain. Because of the vast distances involved, the first settlers were self-sufficient farmers. By the 1840s, however, large scale sheep stations were exporting large quantities of wool to the textile mills of England. Most of the early settlers were brought over by a programme operated by the New Zealand Company and were located in the central region on either side of Cook Strait, and at Wellington, Wanganui, New Plymouth and Nelson. These settlements had access to some of the richest plains in the country and after refrigerated ships appeared in 1882, they developed into closely settled regions of small-scale farming. Outside these compact settlements were the sheep runs. Pioneer pastoralists, often men with experience as squatters in Australia, leased lands from the government at the annual rate of £5 plus £1 for each 1,000 sheep above the first 5,000. The leases were renewed automatically, which gave the wealthy pastoralists a strong landed interest and made them a powerful political force. In all between 1856 and 1876, 8.1 million acres were sold for £7.6 million, and 2.2 million acres were given free to soldiers, sailors and settlers. With an economy based on agriculture, the landscape was transformed from forest to farmland. Gold discoveries in Otago (1861) and Westland (1865), caused a worldwide gold rush that more than doubled the population in a short period, from 71,000 in 1859 to 164,000 in 1863. The value of trade increased fivefold from £2 million to £10 million. As the gold boom ended, Colonial Treasurer and later (from 1873) Premier Julius Vogel borrowed money from British investors and launched in 1870 an ambitious programme of public works and infrastructure investment, together with a policy of assisted immigration. Successive governments expanded the program with offices across Britain that enticed settlers and gave them and their families one-way tickets. From about 1865, the economy lapsed into a long depression as a result of the withdrawal of British troops, peaking of gold production in 1866 and Vogel's borrowing and the associated debt burden (especially on land). Despite a brief boom