16 DRY-LAND OLIVE CULTURE IN NORTHERN AFRICA. 



December being the month of greatest rainfall, with a second maxi- 

 mum, only slightly lower, in April. July and August are the driest 

 months. 



The total rainfall at Sfax varies greatly in different years. Thus, 

 in 1890 it amounted to 17.4 inches, and in 1895 it was only 3.2 inches. 

 During the seven years from 1898 to 1904 the total rainfall was only 

 41 inches; hence the yearly average was only 5.8 inches. The rela- 

 tion that apparently exists between the rainfall and the size of the 

 olive crop is discussed farther on. 



There are no perennial streams in the Sfax region. The inhabi- 

 tants depend upon wells and cisterns for water for irrigating their 

 gardens and newly set out olive trees as well as for household pur- 

 poses. The wells vary greatly in depth. For instance, about 30 

 miles north of the town there is a well 220 feet deep, while only 34 



town and the olive orchards, the roads are bordered by cisterns of 

 a peculiar type (fig. 3). A concrete platform, often 40 or 50 feet 

 square and about 2 feet high at the edge, slopes from all sides 

 toward the center, the opening of which is protected by a con- 

 crete cover. Small holes in the sides of the cover allow the water 

 that falls upon the platform to enter the cistern beneath. Water is 

 drawn when needed through a hole in the top of the cover, which is 

 protected by a movable lid. This type of cistern has been used in 

 Tunis for two thousand years or more. 



In years of unusually small rainfall, such as 1904, water becomes 

 so scarce that 4 or 5 gallons (the capacity of the ordinary water jar 

 used by the natives) are retailed for 2 cents. It has been necessary 

 at times to import drinking water from Naples and to use sea water 

 for washing clothes. 



c 



L_ 



miles away there 

 is a 33-foot well. 

 The average 

 depth is perhaps 

 between 50 and 80 

 feet. 



Fig. 3. — Diagram showing construction of cisterns at Sfax, being 

 a section through two of the openings (o) in the concrete 

 cover (/) by means of which water that falls upon the plat- 

 form {p) enters the cistern (c) ; s is the surface of the soil. 



In the zone of 

 •gardens contain- 

 ing a variety of 

 fruit trees which 

 lies between the 



125 



