876 
EXTENT OF LANDS IEEIGATED. 
another; no more is withdrawn from the canals at any one 
point than is absorbed by the soil it irrigates, or evaporated 
from it, and, consequently, it is not restored to liquid circula¬ 
tion, except by infiltration or precipitation. We are safe, then, 
in saying that the humidity evaporated from any artificially 
watered soil is increased by a quantity bearing a large propor¬ 
tion to the whole amount distributed over it; for most even 
of that which is absorbed by the earth is immediately given 
out again either by vegetables or by evaporation. 
It is not easy to ascertain precisely either the extent of sur¬ 
face thus watered, or the amount of water supplied, in any 
given country, because these quantities vary with the character 
of the season; but there are not many districts in Southern Eu¬ 
rope where the management of the arrangements for irrigation 
is not one of the most important branches of agricultural labor. 
The eminent engineer Lombardini describes the system of irri¬ 
gation in Lombardy as, “ every day in summer, diffusing 
over 550,000 hectares of land 45,000,000 cubic metres of water, 
which is equal to the entire volume of the Seine, at an ordi¬ 
nary flood, or a rise of three metres above the hydrometer at 
the bridge of La Tournelle at Paris.” * Kiel states the quan¬ 
tity of land irrigated in the former kingdom of Sardinia, includ¬ 
ing Savoy, in 1856, at 240,000 hectares, or not much less than 
600,000 acres. This is about four thirteenths of the cultivable 
soil of the kingdom. According to the same author, the irri¬ 
gated lands in France did not exceed 100,000 hectares, or 
247,000 acres, while those in Lombardy amounted to 450,000 
hectares, more than 1,100,000 acres.f In these three states 
alone, then, there were more than three thousand square miles 
of artificially watered land, and if we add the irrigated soils 
of the rest of Italy, of the Mediterranean islands, of the Span¬ 
ish peninsula, of Turkey in Europe and in Asia Minor, of 
Syria, of Egypt and the remainder of Northern Africa, we 
shall see that irrigation increases the evaporable surface of the 
* Memorie sui progetti per V extensions delV Irrigazione , etc., il Politec- 
nico, for January, 1863, p. 6. 
t Niel, VAgriculture des Mats Sardes , p. 232. 
