Harry William Miller, a mining and mechanical engineer residing in Johannesburg, was a foundation member of the South African Association of Engineers and Architects, established in 1892. He served as vice-president for 1897/8, and as president for 1898/9. Just before he was elected president the association changed its name to the South African Association of Engineers. On 25 May 1898 he read a paper before the association describing "A modern brickmaking plant in the Transvaal" (near Johannesburg). Soon thereafter he left on a short visit to Europe.
Miller became a member of the Chemical and Metallurgical Society of South Africa in 1897. He remained a member when the society was revived after the Anglo-Boer War (1899-1902) as the Chemical, Metallurgical and Mining Society of South Africa. By the end of 1903 he had moved to Cape Town, where he worked for Cunningham & Gearing Engineering, a firm of mechanical, electrical, marine and irrigation engineers. He was a foundation member of the South African Association for the Advancement of Science, established in 1902, and at the association's annual congress in 1910, held in Cape Town, contributed "Some notes in reference to the machinery in use in the Transvaal shortly after the retrocession of the country to the British" (Report, 1910, pp. 270-284). His membership of the association had ended by 1911. However, he was still living in 1938 (Orr, 1938, p. 15).
Miller was a member of the (British) Institution of Mechanical Engineers, a member of the American Institute of Mining Engineers, and an associate member of the (British) Institution of Civil Engineers. He had at least one son.