Manchester to study the mill system and memorised some of its details. In the same year, Paul Moody built the first successful power loom in the US. Moody used a system of overhead pulleys and leather belting, rather than bevel gearing, to power his machines. The group devised the Waltham System of working, which was duplicated at Lowell, Massachusetts and several other new cities throughout the state. Mill girls, some as young as ten, were paid less than men, but received a fixed wage for their 73-hour week. They lived in company-owned boarding houses, and attended churches supported by the companies. In the 1840s George Henry Corliss of Providence, Rhode Island improved the reliability of stationary steam engines. He replaced slide valves with valves that used cams. These Corliss valves were more efficient and more reliable than their predecessors. Initially, steam engines pumped water into a nearby reservoir that powered the water wheel, but were later used as the mill's primary power source. The Corliss valve was adopted in the UK, where in 1868 more than 60 mill engines were fitted with them. India The large steam-powered Bowreath Cotton Mills opened at Fort Gloster near Calcutta by British interests in the 1820s, using British women to impart machine-spinning skills to the local workforce. They closed down in 1837 but reopened with Dwarkanath Tagore as a major shareholder, and by 1840 lay at the centre of a major industrial complex powered by five steam engines, that included a twist mill, foundry and a rum distillery. Golden Age (1855–1898) United Kingdom Just before 1870, a mill was built by a joint-stock spinning company and this financial structure led to a new wave of mill construction. The phrase Oldham Limiteds describes these companies. Family-run firms continued to build, but grouped into associations such as the Fine Spinners' and Doublers' Association. Joseph Stott of Oldham perfected a method of fireproof floor construction using steel beams supporting brick vaults that in turn supported concrete floors that would support heavier equipment. Ring frames replaced mule frames; they were heavier and larger and were placed transversely, the floors became larger (up to wide) and higher to provide light. The bay size in a mill was defined by the positioning of machines. In an 1870 mill the bay was typically , and the brick vaults though there were variations. Engines were run at higher pressures and from 1875,