John Craig Watson became a member of the Mechanical Engineers' Association of the Witwatersrand before the end of 1898 and delivered a paper on 'Crushers' at one of its early meetings. By 1897 he was an associate of the Chemical and Metallurgical Society of South Africa (from 1902 the Chemical, Metallurgical and Mining Society of South Africa) and by 1903 an associate member of the (British) Institution of Mechanical Engineers and a member of the South African Association for the Advancement of Science, the latter until sometime after 1906. In 1903 he resided in Johannesburg.
One John Craig Watson, presumably him, continued his studies in the Department of Mining Engineering and Metallurgy of the Massachusetts Institute of Technology, United States, where he submitted a dissertation in 1911 on The concentration of a gold ore from the Transvaal, Ore No. 2751A.