Otto Stuhaug Tonnesen was a Norwegian citizen resident in Johannesburg around 1909 to 1915. He passed the Survey Certificate Examination of the University of the Cape of Good Hope in 1905 and by 1912 was a member of the Chemical, Metallurgical and Mining Society of South Africa. In 1909 he published a paper on 'Stope measurement' in the society's Journal (Vol. 9, p. 375), followed a few years later by a paper on a 'Simplex stope measuring instrument' (1912, Vol. 13(1), pp. 8-10). In 1915 he was granted a United States patent for an improved method for mounting rock drills.
In 1917 O.S. Tonnesen was a mental patient in the Cape Province. And in 1930 Othar Stuhaug Tonn, formerly known as Otto Stihaug Tonnesen, was mentioned in a document that is now in the Natal Archives.