480 Artificial Irrigation. | Oct., 
which minor channels are led off for the purpose of distributing the 
water to the various fields or divisions of land. Where existing 
lakes are to be found, the process of leading off the water in canals 
is simple enough, but artificial reservoirs are often constructed by 
damming up a gorge in a range of hills, in which is collected and 
stored all the raimfall draining into it; and where rock abounds a 
practice prevails in some parts, of excavating a subterranean passage 
having the usual slope of an irrigation canal, in the direction where 
water is supposed to exist. We shall notice these various methods 
of obtaiming supplies of water for artificial irrigation more in 
detail hereafter, when the several varieties of each form of work will 
also be further described. 
It is impossible now to state, with any degree of certainty, 
which was the first country to introduce a system of irrigation, but 
it would appear from the records in our possession that the palm of 
priority must be yielded to Spain over Italy, but France was pro- 
bably before Spain, and Africa anterior to anyin Europe. Whether 
irrigation was introduced into Africa before the second century it 
would be difficult now to determine, but if not, then the Peninsula 
of India may perhaps claim to have first received the benefits of 
irrigation. Mr. Markham, in his ‘ Report on the Irrigation of 
Eastern Spain,’ states that the works of irrigation which are met 
with along the eastern coast of Spain from Cartagena to the mouth 
of the Ebro, in the old Arab kingdoms of Murcia and Valencia, “all 
owe their origin, and the rules and customs by which they are 
managed, to the ancient Arab rulers of the Peninsula, and have 
been in working order for upwards of a thousand years; though in 
some instances they have been enlarged and improved in more 
modern times. It is probable that there were some few irrigation 
works in this region, even in the time of the Romans, when Spanish 
agriculture was represented by Lucius Columella ; but this is uncer- 
tain, and to the Spanish Arabs the credit is due of having instituted 
a system whereby the rocky deserts and dried-up valleys of the 
Peninsula were converted into terraced gardens and fertile vegas. 
The government of the Caliphs of Cordova, so far as its Public Works 
Department was concerned, was certainly the most efficient that has 
ever existed in the world, with possibly the single exception of 
that of the Yncas of Peru; and to the long period of peace and 
prosperity which was secured to this part of Spain by the firm 
and benevolent rule of the Ommiad Caliphs, is to be referred the 
execution of the great works of irrigation in Murcia and Valencia. 
Some of these works are actually ascribed to particular reigns, and 
there can be little doubt that all date their origin from this period, 
about A.D. 760 to 960. The subsequent centuries of Arab dominion 
were periods of strife and internal dissension, ending in a struggle 
or existence. Those were not times for originating public works, 
