Missionary. Born in Rhynie (Aberdeenshire), the son of a Free Church minister, Mackay was educated at Aberdeen Grammar School followed by the Free Church Training College for Teachers in Edinburgh. He then studied engineering at the University of Edinburgh, while teaching part-time at George Watson's College. He went to Germany in 1873 spending three years learning the language, while working for an engineering firm. As recreation, he translated a book on calculus and constructed an agricultural machine of his own invention, which was awarded first prize at the Breslau Exhibition. Determined to become a missionary, he offered his services to the Church Missionary Society and returned to Britain in 1876 to set sail for Africa with a small group of others. After a long delay caused by illness, and several being killed en route, the remainder of the group arrived in Uganda in 1878. Within three years he was the only survivor in a dangerous region where tribal differences were reinforced by the intervention of different European powers, yet he worked hard to the benefit of local tribes, building houses, roads, machinery, and boats.
Mackay died at Usambiro (Uganda) from malaria.
