"after 1746 there was an entirely new level of participation by Scots in political life, particularly outside Scotland." Davidson also states "far from being 'peripheral' to the British economy, Scotland – or more precisely, the Lowlands – lay at its core." In the Highlands, clan chiefs gradually started to think of themselves more as commercial landlords than leaders of their people. These social and economic changes included the first phase of the Highland Clearances and, ultimately, the demise of clanship. 19th century The Scottish Reform Act 1832 increased the number of Scottish MPs and widened the franchise to include more of the middle classes. From the mid-century, there were increasing calls for Home Rule for Scotland and the post of Secretary of State for Scotland was revived. Towards the end of the century Prime Ministers of Scottish descent included William Gladstone, and the Earl of Rosebery. In the late 19th century the growing importance of the working classes was marked by Keir Hardie's success in the Mid Lanarkshire by-election, 1888, leading to the foundation of the Scottish Labour Party, which was absorbed into the Independent Labour Party in 1895, with Hardie as its first leader. Glasgow became one of the largest cities in the world and known as "the Second City of the Empire" after London. After 1860, the Clydeside shipyards specialised in steamships made of iron (after 1870, made of steel), which rapidly replaced the wooden sailing vessels of both the merchant fleets and the battle fleets of the world. It became the world's pre-eminent shipbuilding centre. The industrial developments, while they brought work and wealth, were so rapid that housing, town-planning, and provision for public health did not keep pace with them, and for a time living conditions in some of the towns and cities were notoriously bad, with overcrowding, high infant mortality, and growing rates of tuberculosis. While the Scottish Enlightenment is traditionally considered to have concluded toward the end of the 18th century, disproportionately large Scottish contributions to British science and letters continued for another 50 years or more, thanks to such figures as the physicists James Clerk Maxwell and Lord Kelvin, and the engineers and inventors James Watt and William Murdoch, whose work was critical to the technological developments of the Industrial Revolution throughout Britain. In literature, the most successful figure of the mid-19th century was Walter Scott. His first prose work, Waverley in 1814,