the sea-coast of great fertility. The most
important mountain range is the (so-called) "Mysian" Olympus (7600 ft.),
which towers above Brusa and is clearly visible as far away as
Constantinople (70 m.). Its summits are covered with snow for a great
part of the year. East of this the range now called Ala-Dagh extends far
above 100 m. from the Sangarius to Paphlagonia. Both of these ranges
belong to that border of mountains which bounds the great tableland of
Asia Minor. The country between them and the coast, covered with forests
and traversed by few lines of route, is still imperfectly known. But the
broad tract which projects towards the west as far as the shores of the
Bosporus, though hilly and covered with forests--the Turkish Aghatch
Denizi, or "The Ocean of Trees"--is not traversed by any mountain chain.
The west coast is indented by two deep inlets, (1) the northernmost, the
Gulf of Ismid (anc. Gulf of Astacus), penetrating between 40 and 50 m.
into the interior as far as Ismid (anc. Nicomedia), separated by an
isthmus of only about 25 m. from the Black Sea; (2) the Gulf of Mudania
or Gemlik (Gulf of Cius), about 25 m. long. At its extremity is situated
the small town of Gemlik (anc. Cius) at the mouth of a valley,
communicating with the lake of Isnik, on which was situated Nicaea.

The principal rivers are the Sangarius (mod. Sakaria), which traverses
the province from south to north; the Rhyndacus, which separated it from
Mysia; and the Billaeus (Filiyas), which rises in the Ala-Dagh, about 50
m. from the sea, and after flowing by Boli (anc. Claudiopolis) falls
into the Euxine, close to the ruins of the ancient Tium, about 40 m.
north-east of Heraclea, having a course of more than 100 m. The
Parthenius (mod. Bartan), the boundary of the province towards the east,
is a much less considerable stream.

The natural resources of Bithynia are still imperfectly developed. Its
vast forests would furnish an almost inexhaustible supply of timber, if
rendered accessible by roads. Coal also is known to exist near Eregli
(Heraclea). The valleys towards the Black Sea abound in fruit trees of
all kinds, while the valley of the Sangarius and the plains near Brusa
and Isnik (Nicaea) are fertile and well cultivated. Extensive
plantations of mulberry trees supply the silk for which Brusa has long
been celebrated, and which is manufactured there on a large scale.

According to ancient authors (Herodotus, Xenophon, Strabo, &c.),