feet 6 inches. The Umtali to Beira section was widened to Cape gauge in 1899 and 1900. These lines were proposed before the economic potential of the Rhodesias was fully known, and in the hope that the expected gold discoveries would promote economic development. Rhodesia's gold deposits proved disappointing, and it was the coal of Wankie that first provided the traffic and revenue to fund railway construction to the north. After the discovery of its huge coal reserves, a branch to Wankie from the main line from Bulawayo (which had been extended to cross the Victoria Falls in 1902) was completed in 1903. The next section was to Broken Hill, which the railway reached in 1906. BSAC was assured that there would be much traffic from its lead and zinc mines, but this did not materialise because technical mining problems. The railway could not meet the costs of the construction loans, and the company faced major financial problems, which were already serious because of the cost of widening the Beira railway. The only area likely to generate sufficient mineral traffic to relieve these debts was Katanga. Initially, the Congo Free State had concluded that Katanga's copper deposits were not rich enough to justify the capital cost of building a railway to the coast, but expeditions between 1899 and 1901 proved their value. Copper deposits found in Northern Rhodesia before the First World War proved uneconomic to develop. In 1906 Union Minière du Haut Katanga was formed to exploit the Katanga mines. King Leopold favoured a railway route entirely in Congolese territory, linked to the Congo River. An Angolan railway from Lobito Bay to Katanga was also proposed, but in 1908, the BSAC agreed with Leopold to continuing the Rhodesian railway to Elizabethville and the mines. Between 1912, when full-scale copper production began, until 1928 when a Congolese line was completed, almost all of Katanga's copper was shipped over the Rhodesian network to Beira. Even after the Congo route was opened, up to a third of Katanga's copper went to Beira, and the mine's the supply of coal and coke mostly came from Wankie, the cheapest available source. This railway's revenue from Katanga enabled it to carry agricultural produce at low rates. Large-scale development of the Copperbelt only began in the late 1920s, with an increasing world market for copper. Transport was no problem as only short branches had to be