THE RAIN-FALL IN THE WESTERN PROVINCES. The rain fall for the years 1886, 1887 and 1888 was as follows: 265 The mean monthly rain-fall by seasons for the fifteen years was as follows: Spring, 205.3; summer, 488.2; autumn, 233.6; winter, 31.1. CORDOBA.-The province of Cordoba is partly pampa and partly mountainous, and, exhibiting great diversity in the quality of the soil, is admirably adapted for agricultural pursuits and grazing, the only drawback being a tendency to droughts during the summer months. The city of Cordoba is situated on the banks of the Rio Primero, just on the edge of the great plain which extends to the Atlantic Ocean, the Sierras rising on the west to a height of 2,500 feet. I have the mean monthly temperature for the last fifteen years, and there is a remarkable uniformity in the figures. I give the following for the year 1887: The rain-fall likewise shows a remarkable uniformity. I have the returns for the last fifteen years, and the largest amount in any one year was 988.7 millimeters, in 1878, and the smallest amount was 528.7, in 1887. For the years 1887 and 1888 it was as follows: The mean monthly rain fall by seasons for the last eight years was as follows: Spring, 194.3; summer, 310.6; autumn, 144.3; winter, 16.1. I might extend these meteorological returns, but they are quite sufficient to show the character of the climate in the irrigated regions, and the annual amounts of rain-fall. From an examination of them it will readily be understood that without some artificial means of watering the soil there would not be moisture sufficient for the production of crops with any certainty, unless, perhaps, in Tucuman and Cordoba. SOURCES OF THE WATER SUPPLY. The water supply in all these provinces for the purposes of irrigation is almost exclusively from rivers, streams, springs, and small water courses, coming down from the mountains. The great trouble, however, with those rivers which have their sources in the Cordilleras of the Andes is their unequal volume of water. With the melting of the snows, or during the rainy season, they are generally full to overflow. ing; but they soon run out and at the very times when their waters are most needed. Indeed, with the exception of the system of rivers which flow to the Rio de la Plate and which includes the Uruguay, the Parana, the Paraguay, the Pilcomayo, the Vermijo, and the Salado, there is not a single river in the entire Republic, until we come to the rivers south of the province of Buenos Ayres, which has any outlet. Those of the central system, most of which cross the province of Cordoba, after a dreary course to the eastward, are swallowed up in sands before they reach the Parana. Those which compose the system of the Cordilleras are all lost in quagmires and marshy lagunas before they reach the ocean. With their shallow beds running down very slight inclines, and their great evaporation from the high temperature of summer, many of them quite dry up during four or five months of the year, and these streams are all in those belts of country which have the greatest need of moisture. CHARACTER OF THE IRRIGATION WORKS. In regard to the character of the works used for the storage and distribution of the water, as a general thing, it may be said that they are of the most primitive kind. In most cases they consist merely in holding the waters by means of dams built at intervals along the courses of the streams and from the higher levels thus obtained, making canals or aqueducts through which the water is allowed to pass by a gradual descent as it is needed to the lands which are to be irrigated. From these canals the water is distributed by means of sluices and gateways along a system of drains, trenches, or conduits to the fields and meadows which compose the irrigation district. Where the surface is level or flat it is frequently necessary to form artificial slopes for the water to pass over. The whole of the ground is then laid in broad, undulating beds, the upper part of which is quite level from end to end, where the supply channel is cut. All the supply furrows are fed by a main channel at right angles to the beds and somewhat above them. When the flood-gates are opened the water flows into all the upper channels very regularly and evenly till it fills them to overflowing in their entire length. In the case of those streams which come down from the heights of the Andes and course through the valleys or cañons of the Sierras there is no difficulty in holding the water at a higher level than the lands to be irrigated, but where the sluggish rivers meander across an almost level plain, there is occasion sometimes for engineering and the taking of levels. In some instances a channel receiving the water at a higher point than that to which the river flows is dug at a less declivity than that of the bed of the stream and made to carry the water higher than the banks of the river, from which level it is allowed to descend slowly and irrigate the intervening district. In some parts of the Cuyo prov inces the works which serve as reservoirs for retaining the waters are of solid masonry, and large sums of money have been spent in their construction. In other provinces the works are merely wooden barriers |