Eustace Moriarty Weston, mining engineer, was the son of Edward Weston and his wife Kate McCarthy Clerke. He was trained at and became an associate of the Ballarat School of Mines in New South Wales, Australia. In 1896 he married Catherine Weinritter, with whom he had a daughter. They were later divorced and in 1926 he married Mary Priestly.
By 1905 Weston had emigrated to South Africa where he became the manager of Rand Collieries, Ltd. In 1911 he lectured in mining at the South African School of Mines and Technology, Johannesburg (which later developed into the University of the Witwatersrand). He was an associate of the Chemical, Metallurgical and Mining Society of South Africa and in 1905/6 contributed "Notes on the construction and practical operation of rock-drilling machines" to its Journal. In 1908 he was granted a patent for a new or improved water supplying device for rock-drilling machines. Subsequent papers by him in the same journal dealt with "The theory of blasting with high explosives" (1908), "A new method of lighting fuse" (1910/11), and "Gold production in relation to humanity" (1912/13). During this period he also published what was probably his most important contribution to mining engineering, Rock drills: Design, construction and use (New York, 1910, 367pp). He also published a small (undated) treatise entitled Practical mining on the Rand (Johannesburg) and a paper on "Tin mining and ore dressing in South Africa" (Engineering and Mining Journal, New York, 1910).
From 1913 to 1921 Weston published several papers on economically important mineral deposits: "Bushveld tin deposits" (Mining Magazine, London, 1913); "Tin deposits near Cape Town" (South African Mining Journal, 1914); "Notes on an underground spring of water containing manganese and lithium" (Journal of the Chemical, Metallurgical and Mining Society of South Africa, 1916/7); "Bwana M'Kubwa Copper Mine, North Rhodesia" (Ibid, 1919/20); "Copper prospects in Namaqualand" (South African Mining and Engineering Journal, 1919); and "Occurrence of platinum in South Africa" (Engineering and Mining Journal, 1921).
In 1917 Weston protested to the government of the Union of South Africa against the locking up of mineral deposits along the Mozambique border that would result from converting the game reserves there into a National Park. In 1924 he applied for permission to prospect for gold and platinum in the Shingwidzi Game Reserve (now part of the Kruger National Park).