446 EFFECTS OF AQUEDUCTS AND CANALS. 
of such operation is extended, their influence will make itself 
felt in the diminished supply of water in springs and wells.* 
Geographical and Meteorological Liffects of Aqueducts, 
Reservoirs, and Canals. 
Many of the great processes of internal improvement, such as 
aqueducts for the supply of great cities, railroad cuts and em- 
bankments, and the like, divert water from its natural channels, 
and affect its distribution and ultimate discharge. The col- 
lecting of the waters of a considerable district into reservoirs, 
to be thence carried off by means of aqueducts, as, for ex- 
ample, in the forest of Belgrade, near Constantinople, deprives 
the grounds originally watered by the springs and rivulets of 
the necessary moisture, and reduces them to barrenness.f Sim- 
ilar effects must have followed from the construction of the 
numerous aqueducts which supplied ancient Rome with such 
* Babinet condemns the general draining of marshes. ‘‘ Draining,” says 
he, ‘‘ has been much in vogue for some years, and it has been a special object 
to dry and fertilize marshy grounds. I believe that excessive dryness is thus 
produced, and that other soils in the neighborhood are sterilized in propor- 
tion.” —Etudes et Lectures, iv., p. 118. 
‘¢' The extent of soil artificially dried by drainage is constantly increasing, 
and the water received by the surface from precipitation flows off by new chan- 
nels, and isin general carried off more rapidly than before. Must not this 
fact exercise an influence on the régime of springs whose basin of supply thus 
undergoes a more or less complete transformation ?”—BERNUARD CoTTA, 
Preface to PARAMELLE, Quellenkunde, p. vii., viii. 
The effects of agricultural drainage are perceptible at great depths. It has 
been observed in Cornwall that deep mines are more free from water in well- 
drained districts than in those where drainage is not generally practised.— 
Esqurros, Revue des Deux Mondes, 15 Nov., 1863, p. 430. 
See also ASBJORNSEN, Toro og Torvdrift, p. 31. 
+See a very interesting paper on the Water-Supply of Constantinople, by 
Mr. Homes, of the New York State Library, in the Albany Argus of June 6, 
1872. The system of aqueducts for the supply of water to that city was com- 
menced by Constantine, and the great aqueduct, frequently ascribed to Jus- 
tinian, which is 840 feet long and 112 feet high, is believed to have been 
constructed during the reign of the former emperor. 
