A translated account of the Peruvian expedition of 1736-1746 undertaken by Pierre Bouguer, Louis Godin and Charles de la Condamine of the French Royal Academy of Sciences to measure the degrees of the meridian about the Equator and thence deduce the figure of the Earth. There are descriptions of the country in which the experiments were performed, covering topics such as fauna, wildlife, climate, the influence of the Church, agriculture, geography, soil, ethnography, social stratification, volcanic activity and the Inca civilisation.