TYPES OF SMALL SLUICES &c. FOR IRRIGATION CHANNELS. 0,62 2.8". ELEVATION. -8" OVERFLOW. - PLAN. PLAN. PLAN. 1.4" 2. 8" ELEVATION. 1.6" 3.0" PLAN. 1.8" 1.8" 1.2" Reservoir to receive the Water of the Hydraulic Ram MOUNDS SEPARATING IRRIGATING DEPARTMENTS. Minutes of Proceedings of The Institution of Civil Engineers. Vol: LI. Session 1877-78. Part 1. 49.79 46,99 OPEN CHANNEL MANURE HEAP *47,72 42,45 42,26 36,83 CONDUIT 37,25 30,82 PIPE FOR/ 4428 146,96 CONDUIT PIPE FOR 51,42 49,15 39,64 *40,61 51,07 950,76 533,48 31,48 37,77 183,77 MANURE HEAP. 29,07 30,26 28,50 27,89 IRRIGATING 25,77 25,43 24,99 24,79 24,68 24,29 MANURE HEAP. -35,62 34,79 33,37 32,36 REFERENCE: The Figures denote the Levels in Metres. above the Sea. The Main irrigating Channels for the Estate are shown thus: --- The Minor irrigating Channels for the Estate are shown thus: The Underground Conduit Pipes are about 8 inches diameter. A. Hydraulic Ram for raising Water 18 high to irrigate the higher portion of the Estate. IRRIGA 25,46 25,34 THOS KELL LITH 40.KING. ST COVENT GARDEN. PLATE 6. No. 1,551.-"Irrigation in the South of France: Department of the "Bouches-du-Rhône." By GEORGE WILSON, M. Inst. C.E. THE department of the Bouches-du-Rhône is situated in the south of France, on the shores of the Mediterranean Sea. Marseilles is the chief town. The soil is mostly of a dry calcareous nature and the geographical position is such that generally but a small quantity of rain falls during the spring and summer months. Under the rays of a hot sun and a dry atmosphere, most of the crops become parched for want of moisture, and their production is consequently small in amount. But when the land is irrigated, under such a fine productive climate, crops of all kinds are both luxurious and abundant, consisting of wheat, rye, oats, barley, maize, grass meadows and pastures, luzerne, clover, potatoes, tobacco, madder, beetroot, hemp, vines, olives, mulberries, almonds, &c. Vegetables of all kinds. Fruits of great variety, such as peaches, pears, apples, apricots, plums, cherries, figs, quinces, medlars, pomegranates, jujubes, strawberries, melons, marjorams, mint, &c. The necessity for, and the great benefits to be derived from, irrigating the land have been known, appreciated, and practised by the inhabitants since the time that the Romans quitted the country, of whom there was an important colony in the Bouches-du-Rhône, the town of Arles was the centre of the colony. The climate of the Bouches-du-Rhône, notwithstanding the mistral which blows occasionally, is considered one of the finest and most productive in France. There is comparatively little rain during some of the spring and summer months, and the temperature is high. The annual amount of rainfall varies considerably in different districts, and also yearly for each district, of the department. The following table (see next page) shows the average rainfall at Marseilles from 1860-1871. This table shows that there is a mean rainfall of 11.2 inches for the seven months, March-September. The mean temperatures in the district of Marseilles, from observations continued during more than fifty years, are for the whole year, in degrees Fahrenheit 57° 9; summer, 70°.9 (the maximum being 92° 3 for nine years); and winter, 45°.5. In the district of Arles the mean temperatures for the whole year are 58°·8; summer, 74°·7 (the maximum being 99° 5), winter, 43° 5. For comparison with the above-mentioned rainfalls and temperatures in the Bouches-du-Rhône, the following are particulars of the same for Spain, Italy, and Algiers. For Spain, the mean temperatures at Madrid for summer, April–September, are 67°·8; winter, October-March, 48° 6; at Seville, summer, 81° Fahr., winter, 64°; at Valencia, summer, 75° 5; winter, 57° 6; at Alicante, summer, 71°.9, winter, 58°.8. TABLE SHOWING ANNUAL RAINFALL in ITALY, ALGIERS, and SPAIN.1 1 "Irrigation in Spain," by George Higgin, M. Inst. C.E. Minutes of Proceedings Inst. C.E., vol. xxvii., p. 483. TABLE SHOWING COMPARATIVE MEAN and MAXIMUM TEMPERATURE and MEAN RAINFALL of ITALY and SPAIN DURING the SEVEN IRRIGATING MONTHS from MARCH to SEPTEMBER. The system of irrigation has been for centuries gradually extended in the department of the Bouches-du-Rhône, necessitating the execution of important canals and works, some of which are not surpassed in an engineering sense by any others for a similar purpose, resulting in enormously improving and enriching the country. The geographical position of a large extent of the department is admirably situated for the purpose of irrigation by means of the water of the river Durance, which flows along the north side of the department at a considerable altitude. In Plate 5 is shown a map of a portion of the department with the main irrigating canals, &c., the particulars of which are stated in the reference on the map. Before describing the mode and results of irrigation in the Bouches-du-Rhône, a brief description will be given of the river Durance, from which the irrigation canals mostly derive their waters, and also a few details of four of the main irrigating canals. THE DURANCE. The source of this river is in the Alps, separating France from Italy, and the river flows into the Rhône near Avignon. mountainous basin is about 5,200 square miles superficial area, and its main tributaries are the rivers Verdon, Asse, Bléone, Ubaye, and the Guil, all of which are generally torrential. The inclination of the bed of the Durance is considerable; it increases |