Political essay on the kingdom of New Spain : containing researches relative to the geography of Mexico, the extent of its surface and its political division into intendancies, the physical aspect of the country, the population, the state of agriculture and manufacturing and commercial industry, the canals projected between the South Sea and the Atlantic Ocean, the crown revenues, the quantity of precious metals which have flowed from Mexico to Europe and Asia, since the discovery of the new continent, and the military defence of New Spain /