General studies on the structure and growth of the Brazilian population in the colonial period are rare. Attempts to calculate the size of the population and assess its growth at various dates have been carried out by Roberto Simonsen, História econômica do Brasil (1500–1820), 6th ed. (São Paulo, 1969), and also by Celso Furtado, Formação econômica do Brasil, IIth ed. (São Paulo, 1971). Using information from the third quarter of the eighteenth century, when the first census surveys were carried out in each captaincy, various authors have assembled and organized statistics still preserved in archives, in an attempt to arrive at a demographic aggregate for the country during the period. The following studies, in particular, are worthy of note: Dauril Alden, ‘The population of Brazil in the late 18th century: A preliminary survey’, HAHR, 43/1 (1963), 173–205; Maria Luiza Marcílio, ‘Accroissement de la population: Évolution historique de la population brésilienne jusqu’en 1872’, in Comité International de Coordination des Recherches Nationales en Demographie, La population du Brésil (Paris, 1974); also M. L. Marcílio, ‘Evolução da população brasileira através dos censos até 1872‘, Anais de História, 6 (1974), 115–37. Some scholars have based their figures on different sources. For example, using the more reliable nineteenth-century census figures, they have made retrospective estimates in order to arrive at a probable total for the population of Brazil in the eighteenth century. Such is the case of Giórgio Mortara, ‘Estudos sobre a utilização do movimento da população do Brasil’, Revista Brasileira de Estatística (January-March 1941), 38–46, who calculated the total population of Brazil by year, from 1772.