La medición de un imperio: reconstrucción de los instrumentos utilizados en el proyecto de López de Velasco para la determinación de la longitud

The article discusses the graphical reconstruction of the instruments to determine longitude by observing lunar eclipses, described in Lopez de Velasco’s project to map the New World. Finally, a theoretical proposal is made: although the method to determining longitudes in the eclipse questionnaire has been attributed several times to Juan López de Velasco, who had jurist training, it is unlikely that the royal cosmographer was the inventor of instruments. However, there are also elements that point to the authorship of Juan de Herrera, architect of Philip II