lowering of tiie lake of albano. 
353 
Lowering of Lakes. 
The hydraulic works of the Netherlands and of the neigh¬ 
boring states are of such magnitude, that they quite throw into 
the shade all other known artificial arrangements for defending 
the land against the encroachments of the rivers and the sea, 
and for reclaiming to the domain of agriculture and civiliza¬ 
tion soil long covered by the waters. But although the re¬ 
covery and protection of lands flooded by the sea seems to be 
an art wholly of Netherlandish origin, we have abundant evi¬ 
dence, that in ancient as well as in comparatively modern 
times, great enterprises more or less analogous in character 
have been successfully undertaken, both in inland Europe and 
in the less familiar countries of the East. 
One of the best known of these is the tunnel which serves 
to discharge the surplus waters of the Lake of Albano, about 
fourteen miles from Borne. This lake, about six miles in cir¬ 
cuit, occupies one of the craters of an extinct volcanic range, 
and the surface of its waters is about nine hundred feet above 
the sea. It is fed by rivulets and subterranean springs origi¬ 
nating in the Alban Mount, or Monte Cavo, the most elevated 
peak of the volcanic group just mentioned, which rises to the 
height of about three thousand feet. At present the lake has 
no discoverable natural outlet, but it is not known that the 
water ever stood at such a height as to flow regularly over the 
lip of the crater. It seems that at the earliest period of which 
we have any authentic memorials, its level was usually kept 
by evaporation, or by discharge through subterranean chan¬ 
nels, considerably below the rim of the basin which encom¬ 
passed it, but in the year 397 b. c., the water, either from the 
obstruction of such channels, or in consequence of increased 
supplies from unknown sources, rose to such a height as to 
flow over the edge of the crater, and threaten inundation to 
the country below by bursting through its walls. To obviate 
this danger, a tunnel for carrying off the water was pierced at 
a level much below the height to which it had risen. This 
gallery, cut entirely with the chisel through the rock for a 
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