Mapping the whole errors of Tomas Lopez's geographic atlas of Spain (1804)

Abstract

The Geographic Atlas of Spain (AGE) designed by Tomas Lopez in1804 consisted of an anthology of maps of the Spanish regions that was drawn in the second half of the eighteenth century. It was the most ambitious and successfully completed cartographic work undertaken to date. Nowadays there is no study that examines this work as a whole. This paper analyzes the complete cartographic errors of this work in Spain. A total amount of 90 sheets of maps, from 36 kingdoms or provinces of Spain in 1804 have been analyzed. A total of 21,800 settlements or towns have been digitized, which have been linked to the current ones about 75%. Linear error of each settlement has been calculated by comparing the historical mapping coordinates to the current ones. The average linear error obtained for all analyzed settlements was 6.5 km. Linear errors of all settlements have been represented for Spain by GIS. Finally, an inverse relationship between the higher density of settlements and the largest linear error has been found; as well as the communication networks of that time act as corridors that connect areas of lower errors.