352 DRY-FARMING 
great irrigation systems which would make crops 
certain with a minimum of soil tillage, than so thor- 
oughly to till the soil with imperfect implements 
as to produce certain yields without irrigation. Thus 
is explained the fact that the historians of antiquity 
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Fie. 96. The last of the breast plows. Modern machinery has made 
dry-farming possible. 
speak at length of the wonderful irrigation systems, 
but refer to other forms of agriculture in a most 
casual manner. While the absence of agricultural 
machinery makes it very doubtful whether dry- 
farming was practiced extensively in olden days, yet 
there can be little doubt of the high antiquity of the 
practice. 
Kearney quotes Tunis as an example of the pos- 
sible extent of dry-farming in early historical days. 
Tunis is under an average rainfall of about nine 
inches, and there are no evidences of irrigation having 
been practiced there, yet at El Djem are the ruins 
