DRY-FARMING IN TUNIS AND AMERICA 353 
of an amphitheater large enough to accommodate 
sixty thousand persons, and in an area of one hundred 
square miles there were fifteen towns and forty-five 
villages. The country, therefore, must have been 
densely populated. In the seventh century, accord- 
ing to the Roman records, there were two million 
five hundred thousand acres of olive trees growing in 
Tunis and cultivated without irrigation. That these 
stupendous groves yielded well is indicated by the 
statement that, under the Caesars, Tunis was taxed 
three hundred thousand gallons of olive oil annually. 
The production of oil was so great that from one 
town it was piped to the nearest shipping port. 
This historical fact is borne out by the present revival 
of olive culture in Tunis, mentioned in Chapter XII. 
Moreover, many of the primitive peoples of to-day, 
the Chinese, Hindus, Mexicans, and the American In- 
dians, are cultivating large areas of land by dry-farm 
methods, often highly perfected, which have been 
developed generations ago, and have been handed 
down to the present day. Martin relates that the 
Tarahumari Indians of northern Chihuahua, who are 
among the most thriving aboriginal tribes of north- 
ern Mexico, till the soil by dry-farm methods and 
succeed in raising annually large quantities of corn 
and other crops. A crop failure among them is 
very uncommon. The early American explorers, 
especially the Catholic fathers, found occasional 
tribes in various parts of America cultivating the 
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