The construction of the spanish rule

Abstract

The mid-nineteenth century saw the undertaking of a project that had long been desired by Spanish scientists and politicians: the preparation of an accurate map of Spain. It was to be the largest Spanish scientific undertaking of the century. The geodesic work carried out as the basis for the project was of high quality and placed Spanish geodesy at the forefront of the field worldwide. The project's first sucess was the design, construction, and subsequent utilization of the Spanish Rule, an instrument for taking base measurements, an example of true precision and the first task tackled by Carlos Ibañez e Ibáñez de Ibero, who was later to become the leader of Spanish geodesy. The present article outlines the origins of this cartographic project, briefly examines the caracteristics of the Rule, and tells the story of the difficult process of its construction.