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Jan 1, 1969

Jan 1, 1887

Jan 1, 1914

By P. J. F. Fourie

The purpose and frequency of comprehensive performance testing and the types of tests to be included are discussed. The results obtained from a series of such tests are reviewed.

Jan 1, 1980

Jan 1, 1920

Jan 1, 1946

Jan 1, 1948

Jan 1, 1947

Jan 1, 1947

Jan 1, 1935

Jan 1, 1913

Jan 1, 1896

Jan 1, 1948

Jan 1, 1957

Jan 1, 1886

There are references to the early and continuous production of coal since 1851, but few definite figures. Some data were obtained from Bancroft, but nearly all the tonnages in Table 80, prior to 1869, are estimated. [ ]

Jan 1, 1942

Jan 1, 1930

Jan 1, 1932

Jan 1, 1949