听力原文： At the end of the 19th century, a social scientist visited Stockwell, in south London. He was involved in an ambitious project, led by the shipping magnate Charles Booth, to color-code every street in the capital according to its social make-up. In general, the area struck him as comfortable. But just east of Stockwell Road he found a pocket of filth and squalor, with rude residents and broken windows. It was, he believed, 'far the worst place in the division'. Since then, the area has been transformed. Dismal two-storey cottages have been swept away and replaced by grass and the apartment blocks of the Stockwell Park Estate. But the appearance of the neighborhood has changed more than its character. Julie Fawcett, who lives in one of the blocks, characterizes her neighbors as 'the mad, the bad and the sad'. Unemployment is more than double the area's average. In many ways, London has changed dramatically in the past century. It has sprawled far beyond its 1898 boundaries. The network of underground transport has expanded, and cars have appeared. The city has been bombed in two world wars. The middle classes fled, then returned. Yet when Booth's maps am updated using data from the last census, the changes are less striking than what has stayed the same. Not only do the broad patterns found in the 19th century hold -- the East End is still poor, the West End still rich -- but so do many local ones. Booth's method of judging streets was necessarily impressionistic. Researchers peered through windows and into back gardens in search of clues. A torn waistcoat on a clothes line in Kentish Town, north London, 'told clearly of working-class occupants'. Police officers were asked their opinions. Of the residents of one street in the south London neighborhood of Battersea, the local copper asserted: 'People have improved their houses but not their manners.' That road was coded black, for 'vicious, semi-criminal' -- the lowest of seven categories. Sadly, the 2001 census does not measure viciousness. But it does measure people's socioeconomic status. By collapsing its eight categories, and Booth's seven, into four, it is possible to see how a neighborhood has changed (or not changed) over a century. One area that has altered more than most: north Chelsea. In 1898, Chelsea was socially mixed, and neither especially rich nor especially poor. Booth's researchers found some well-to-do residents in the Georgian terraces and on the main roads before the advent of cars, busy roads were often smart. Worst was a now-demolished street southeast of the Fulham Road, the neighborhood's main drag, which featured 'evil looking drink sodden old Irish women'. A century later, managerial and professional workers are now the dominant group in the area. Many streets that were middling in Booth's day are now wealthy, and some pockets of deep poverty have disappeared. But poverty has not been altogether banished from this part of Chelsea, nor has it moved much. Most of the poorest areas in 2001 were also poor in 1898, and in almost exactly the same places. The reason is that the worst Victorian slums have been knocked down and replaced with tracts of social housing. Some of this housing was built by charitable trusts in the early 20th century. Charles Booth was a ______.