Natural supplies of water increase in number as one gets away from the Andean zone toward the east. Still, the chief work, often the only work, to be done in making a road is the arrangement of permanent supplies of water. Martin de Moussy mentions the digging of wells on the new road from Cordoba to Rosario, which was opened about 1860. The _aiguade_ was generally a _represa_, a reservoir, where the water accumulated behind a barrier of earth raised across the course of an intermittent stream. The upkeep of the _represa_ is the chief duty of the post-master. The edge of the sierras and the opening point of the ravines which come down them is a good place for making _represas_, and the roads frequently keep to these (variant of the road from Cordoba to Tucuman _via_ Totoral, Dormida, Rio Seco and Sumampa, on the eastern edge of the Sierra de Cordoba, etc.) Long stages with no water supplies, the _travesias_, are not found on the made roads, as a rule, except west of the meridian, of Cordoba. However, the direct road from Santa Fe to Santiago del Estero by the lagoon of Los Porongos, which was used in the eighteenth century, seems to have been abandoned afterwards, as much on account of the difficulty of supplying water as because it was exposed to attack from the Indians. [105] J. B. Ambrosetti, "Viaje a la Pampa central," _Bol. Instit. Geog. Argent._, xiv. 1893, pp. 292-368. [Illustration: AN OX WAGON. Photograph by Soc. Fotografica de Aficionados.] [Illustration: THE MAIL COACH. _The horses saddled with the_ cincha. Photograph by Soc. Fotografica de Aficionados. PLATE XVIII. To face p. 210.]