them. Instead they approached the nation's problems pragmatically, keeping in mind the constraints imposed by democratic public opinion. To deal with the issue of land distribution, they worked out innovative solutions to access, tenure, and a graduated tax on unimproved values. Economic developments In the 1870s Julius Vogel's grand go-ahead policy of borrowing overseas had increased the public debt from £7.8 million in 1870 to £18.6 million in 1876, but had constructed many miles of railways, roads and telegraph lines and attracted many new migrants. In the 1880s, New Zealand's economy grew from one based on wool and local trade to the export of wool, cheese, butter and frozen beef and mutton to Britain. The change was enabled by the invention of refrigerated steamships in 1882 and a result of the large market demands overseas. In order to increase production, alongside a more intensive use of factor inputs a transformation of production techniques was necessary. The required capital came mainly from outside of New Zealand. Refrigerated shipping remained the basis of New Zealand's economy until the 1970s. New Zealand's highly productive agriculture gave it probably the world's highest standard of living, with fewer at the rich and poor ends of the scale. During this era () the banking system was weak and there was little foreign investment, so businessmen had to build up their own capital. Historians have debated whether the "long depression" of the late 19th century stifled investment, but the New Zealanders found a way around adverse conditions. Hunter has studied the experiences of 133 entrepreneurs who started commercial enterprises between 1880 and 1910. The successful strategy was to deploy capital economising techniques, and reinvesting profits rather than borrowing. The result was slow but stable growth that avoided bubbles and led to long-lived family owned firms. Dominion and Realm New Zealand initially expressed interest in joining the proposed Federation of the Australian colonies, attending the 1891 National Australia Convention in Sydney. Interest in the proposed Australian Federation faded and New Zealand decided against joining the Commonwealth of Australia in 1901. New Zealand instead changed from being a colony to a separate "Dominion" in 1907, equal in status to Australia and Canada. Dominion status was a public mark of the self-governance that had evolved over half a century through responsible government. Just under one million people lived in New Zealand in 1907 and cities such as Auckland and Wellington