IRRIGATION. 35 



such materials as are ready to hand. By means of these, streams that 

 in summer appear to be dry, but really carry subterranean water, are 

 made to serve for irrigation at that season. The bed is dug out until 

 i-ock bottom is reached. A dam is then roughly fashioned out of 

 stones. The trunk of a tree is laid across the top, which is slightly 

 hiffher than the oeneral level of the stream bed, and clav and stones 

 are piled up ])ehind the dike; or, sometimes, a mere double row of 

 stakes., filled in with clav iind stones, is made to answer the purpose. 



Various devices are in use in Algeria for preventing water that falls 

 upon cultivated hillsides from running off too rapidly. Particular 

 attention has been paid to this ([uestion in vineyards. Sometimes 

 shallow basins are dug in tiie center of each quadrangle formed by 

 four vines. Another practice, which is also followed by the Kal)yles 

 in their orchards, is to run horizontal furrows or trenches across the 

 hillside at regular intervals, throwing out the soil on the downhill 

 side. It has ))een estimated that, at a cost of about $8, from 9, ()()(» to 

 10,000 cu))ic feet of water, enough to cover the land to a depth of from 

 2 to 4 inches, can thus be saved annually in each acre of vineyard. In 

 olive orchards, which cover steep hillsides in some parts of the colony, 

 V-shaped trenches, pointing downhill, are dug so that the point of a 

 trench is situated neai' the base of each tree. The soil around the 

 tree is kept loose in order to facilitate absorption of the water thus 

 carried to it. 



The market gardens of the littoral zoiu> are generally irrigated by 

 means of the " noria,*" a water-lifting machine that has been in use 

 for ages in the Mediterranean region. It consists of a vertical wheel, 

 to the rim of which buckets are attached, and which turns by inter- 

 locking its cogs with those of a horizontal wheel. To the latter an 

 animal, usually a horse or a donkey, is hitched, and is driven around 

 in a circle. A second animal is kept to relieve the first, generally 

 ever}' two hours. By means of the noria one horse can raise 150 

 gallons of water 11 feet in a minute, which is equivalent to 0.33 second- 

 foot. The water is collected in a basin that generally holds from 

 1,000 to 1,800 cubic feet.. Even field crops and vineyards can be 

 profitably irrigated with the noria if the water supply is ample and the 

 lift does not exceed 40 feet. But its greatest usefulness is in connec- 

 tion with the intensively cultivated and very remunerative truck crops. 

 The noria is said to be more economical for raising water than any 

 hydraulic machine, only one-fifth of the total power expended being 

 lost. Near Algiers, where the irrigation of gardens is most expensive, 

 the annual cost of watering 1 acre with the noria is placed at $65. 



The water used for irrigation in the coast region, except in some of 

 the valleys of western Algiera, is generally ver}- good, rarely contain- 

 ing a harmful (Quantity of salts. However, no attention has been given 

 to the matter of drainage of irrigated lands. Particularly in western 



