Augusto de Castilho was Governor of Lorenco Marques (now Maputo) in the Portuguese colony of Mozambique, in about 1876-1878. He subsequently wrote a book (in Portuguese) on the district of Lorenco Marques, the second edition of which was published in Lisbon in 1881. It included sections dealing with the Transvaal Republic and Natal Colony. In February of the same year he presented a lengthy paper dealing with the Transvaal to the Sociedade de Geographia de Lisboa (Geographic Society of Lisbon). This was followed two months later by his translation into Portuguese of a lecture by George P. Moodie*, dealing with the history, politics, and native races of the Transvaal Republic, presented to the same society.
In 1884 Castilho published a paper in Lisbon on meteorological observations made at Lorenco Marques during 1876-1878. It included tables of atmospheric pressure, air temperature, cloudiness, wind direction and force, rainfall, and evaporation. At this time (1884-1885) he was on a voyage on the Portuguese warship Rio Lima, as "Capitao tenente commandante", to South America, South Africa, Mozambique, and East Africa. He visited, among others, Cape Town, Durban, and Pietermaritzburg. His official report on the voyage was published in 1889. Some years later he wrote an account of a diplomatic conflict between Portugal and Brazil (1894). Two more papers by him published in the Boletim da Sociedade de Geographia de Lisboa, both in 1895, dealt with Lourenco Marques and with the island Sao Tome, in the Gulf of Guinea, respectively.