These four "Copper Kings" were William A. Clark, Marcus Daly, F. Augustus Heinze, and James A. Murray. The Anaconda Copper Mining Company began in 1881 when Marcus Daly bought a small mine named the Anaconda. He was a part-owner, mine manager and engineer of the Alice, a silver mine in Walkerville, a suburb of Butte. While working in the Alice, he noticed significant quantities of high grade copper ore. Daly obtained permission to inspect nearby workings. After Daly's employers, the Walker Brothers, refused to buy the Anaconda, Daly sold his interest in the Alice and bought it himself. Daly asked George Hearst, San Francisco mining magnate, for additional support. Hearst agreed to buy one-fourth of the new company's stock without visiting the site. While mining the silver left in his mine, huge deposits of copper were soon developed and Daly became a copper magnate. When surrounding silver mines "played out" and closed, Daly quietly bought up the neighboring mines, forming a mining company. Daly built a smelter at Anaconda, Montana (a company town) and connected his smelter to Butte by a railway. Anaconda Company eventually owned all the mines on Butte Hill. Between 1884 and 1888, W.A. Clark constructed the Copper King Mansion in Butte, which became his second residence from his home in New York City. He also, in 1899, purchased the Columbia Gardens, a small park which he developed into a full amusement park, featuring a pavilion, rollercoaster, and a lake for swimming and canoeing. Clark's expansion of the park was intended to "provide a place where children and families could get away from the polluted air of the Butte mining industry." The city's rapid expansion was noted in an 1889 frontier survey: "Butte, Montana, fifteen years ago a small placer-mining village clinging to the mountain side, has now risen to the rank of the first mining camp of the world... [It] is now the most populous city of Montana, numbering twenty-five thousand active, enterprising, prosperous inhabitants." In 1888 alone, mining operations in Butte had generated an "almost inconceivable" output of $23 million () worth of ore. Around the turn of the twentieth century, prosperous mining had generated considerable wealth in Butte, and at the time was the largest city between Chicago and San Francisco. Copper ore mined from the Butte mining district in 1910 alone totaled ; at the time, Butte was the largest producer of copper in North America and rivaled in worldwide metal production only by South Africa.