Alpheus F. Williams, mining engineer, was the eldest child of the mining engineer Gardner F. Williams* and his wife, Fannie Locke. He studied at Cornell University (in Ithaca, New York State) and at the School of Mines of the University of California, graduating at the latter institution as Bachelor of Science in mining engineering in 1898.
Williams came to South Africa in January 1899 and the next year took up a position as mining engineer at the De Beers Consolidated Mines, Ltd in Kimberley, where his father was general manager. By 1902, when the Anglo-Boer War (1899-1902) had just ended, he had already been promoted to assistant general manager. In 1905 succeeded his father as general manager of the company, a position he held until his retirement at the end of 1931. He led the company during a period of rapid development. In 1921-1922 the central treatment plant for the Bultfontein, Dutoitspan and Wesselton mines was erected under his guidance.
Williams's earliest local publication of scientific interest was a pamphlet, American engineers in South Africa (Kimberley, 1902, 19p), which listed the names of 70 engineers with their qualifications and work experience in the United States and in South Africa. In 1913 he contributed a major paper on "The Kimberley system of handling large quantities of ground in the minimum of time, with some notes regarding the life of wire ropes", to the Transactions of the South African Institution of Engineers (1913, Vol. 1, pp.71-128). This paper had been delivered two or three years earlier, and earned him the first gold medal (for 1910/11) awarded by the institution. Just before the outbreak of World War I (1914-1918) he and Ernest Oppenheimer were sent to German South West Africa (now Namibia) to report on the diamond fields along the coast between L?deritz and Bogenfels. Their report to the chairman and directors of the company, dated 4 June 1914, was published under the title Diamond deposits of German South West Africa (Kimberley, 1914, 58p). Another major paper by him, "Diamond-bearing alluvial gravels of the union of South Africa", was published in the British Empire Mining and Metallurgical Congress Handbook (Johannesburg, 1930, pp. 1-169). Probably his most important work was a book, The genesis of the diamond. A geological, mineralogical, crystallographical, petrographical and chemical study of Kimberlite and its associated cognate and accidental inclusions (London, 1932, 2 vols). That same year he was co-author, with J. Parry and F.E. Wright, of a paper "On Bultfonteinite, a new fluorine-bearing hydrous calcium silicate from South Africa" (Mineralogical Magazine, 1932). Years later he wrote a popular book, Some dreams come true, being a sheaf of stories leading up to the discovery of copper, diamonds and gold in southern Africa and of the pioneers who took part in the excitement of those early days (Cape Town, 1949).
In 1902 Williams became a foundation member of the South African Association for the Advancement of Science, serving on its council for 1907/8 and 1908/9. When the British Association for the Advancement of Science held its annual meeting in South Africa in 1929 he was elected as one of 26 vice-presidents for this meeting.
After leaving De Beers Williams and his sons established the structural engineering firm Alpheus Williams & Dowse. By 1936 he was living at Constantia, Cape Town. He was a man with many interests and abilities and led an active public life. In 1902 and 1903 he was an examiner in the subject mining, for the second mining examination of the University of the Cape of Good Hope. When the so-called Spanish influenza reached South Africa in 1918 he was appointed as an emergency member of the Kimberley Board of Health and wrote a comprehensive Report... on the epidemic of Spanish influenza in Kimberley (Kimberley, 1918, 46p). He was appointed as consular agent in Kimberley for the United States in 1906; was a director of the South African Permanent Mutual Building and Investment Society; formed the first South African brigade of the St John Ambulance Society in Kimberley in 1912; was appointed district superintendent for Griqualand West in 1917; served as assistant commissioner and commissioner for the Cape Province from 1921 for many years; and was the first president of the South African Poultry Association. He was also chairman (later a member) of the board of management of the McGregor Museum from its origin in 1907 for many years. In 1931 he was honoured by the British government as a Knight of Justice in the Order of St John of Jerusalem. In May 1903 he married Constance Smith, with whom he had four sons. One of his sons was named Alpheus Fuller like his father, another Alpheus Gardner.