ITALY
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turns towards the south-east, terminating against the
embankment of the Reno, a river that rises near Pru-
netta, passes to the east of Bologna, flows by Pieve di
Cento, and, turning towartls the east, enters the old
channel of the Po di Primaro and empties into the sea
at Porto Primaro, after a course of 124 miles. The
Idice, Santeriio, and the Senio are its affluents, (d)
The rivers of Istria are very short, with little water,
and flow in channels from which they disappear into
the ground, to appear again in other channols or near
the sea. The Recca-Timavo is the most important
one of them; after a course of 28 miles in a narrow
channel, it disappears into a cave, and it is probable
that its waters go through the Carso and that they are
the same that emerge from great springs, near Monfal-
the lake that occupied the valley of Chiana and was a
tributary of the Tiber through the Paglia. Now the
Arno, abreast of .\rezzo, arches round the Pratomagno
and flows through a series of narrow passes between
that chain and the mountains of Chianti. At Pontas-
sieve it receives the Sieve which flows through the
valley of Mugello, and then, turning directly to the
west, it enters upon the second straight course; it
flows through Florence, receives the Bisenzio and the
Ombrone of Pistoia and flows through the plain of
Prato which was once the l^ottom of a lake; it enters
the Pass of Golfolina, 7+ miles in length, between Mt.
Albano and the mountains of Chianti; thereafter it
receives the Pesa, the Elsa, and the Era, on the left,
and the Pescia on the right — and in all this second
cone, and empty into the Monfalcone Gulf under the
name of Timavo. The other rivers, the Dragogna,
the Quieto, the Leme. which rises under the name of
Foiba, all develop fords at their mouths, and the Foi-
ba disappears and reappears several times; the Arsa
empties into the Gulf of (Juarnero.
On account of the bow shape of the Central Apen- nines the rivers that empty into the Adriatic Sea are very short and almost straight, while those that empty into the Tyrrhenian Sea are longer, and have a sinu- ous course in the longitudinal valleys through which they flow. They cut narrow channels through the mountain ranges or at times form cataracts like those of Marmore, near Terni (5:i0 feet), those of Tivoli, and those of the Filireno. Many of the long valleys be- tween the Ant i- A ponnino ami the Sub-.\pennine ranges were occupied b,\ lakc^ that were either filled in natu- rally by the allm ia! ilcpnsits of the rivers or were arti- ficially drained, as wi-re the valley of Chiana, the val- ley of the Tiller, the plain of Foligno, the lands of Reati,of Fucino, and others. The .\rno River, which has an average breadth of from 330 to 500 feet, rises on Mt. Falterona (5400 feet) and flows towards the south- east between the Apennines and the Pratomagno, through a beautiful spacious valley that is the con- tinuation of the ^'al di Chiana and is called Casen- tino. It appears that formerly the Arno flowed into
course it flows over a low plain, between powerful
artificial embankments. It empties into the sea at
6 miles from Pisa through a delta that is carried for-
ward 16 feet each year. The Tiber (Tiberis). — This
is the most famous of all rivers, because there stands
on its banks the city which of all has exercised the
greatest influence upon the world, in ancient, as well
as in modern, times. Geograpliically. the Tiber is the
second river of Italy, in relation to its basin, and the
third, in relation to its length, the first and the second
being the Po and the Adige respectively. It flows
from north to south, winding along the tenth meridian
East of Greenwich, with an average breadth of about
500 feet, while the volume of its flood is 9500 cubic
feet per second. It has a very sinuous course which is
divided into four parts; the first of them is through a
longitudinal valley, between the Apennines and the
Sub-Apennines, called the Valley of the Tiber, the
river passing by the town of Santo Sepolcro and the
Citta di Castello. It leaves Perugia on the right and
receives the Chiascio, a river that has for affluents the
Topino, which comes from the plain of Gubbio, and
the Maroggia which it.self receives the abundant
waters of the Clitunno. At its juncture with the
Chiascio, the Tiber begins its second tract: flowing in
a south-easterly direction through a narrow valley of
the Sub-Apennines of fimbria, it leaves Todi oii its
