72 PASSES OF CAUCASUS. 
of subordinate out-works were visible. The face of the moun¬ 
tain behind the tower had been hewn, with manifest great 
labour, into a kind of aqueduct, to convey water to the garrison. 
And, when we consider that there would be ground within its 
lines to supply themselves and cattle with food, we could not 
suppose a place better adapted for the purposes of such a station. 
A subterraneous passage runs down from* the castle to the bank 
of the river, communicating, probably, with other works which 
might be below, to bar more immediately, the ingress of the 
valley. The pass, at this place, is not more than thirty yards 
across ; which facility of nature, agreeing with the vestiges along 
its borders, leaves no doubt in my mind that this, from earliest 
times, has been one of the main doors of communication with 
the nations of the north, direct from Iberia. Pliny thus describes 
these defiles of the Caucasus, and the mode of maintaining 
them : — “ Each pass was closed by large beams of wood, 
pointed with iron. In the midst of the narrow valley flowed a 
a river. The southern extremity was protected by a castle built 
on a high rock. This defence was to prevent incursions from 
the people of the north.” * 
According to Ptolemy, there were three of these great passes. 
The Pyle Sarmatce , the Pyle Albanie , and the Via Caspia. It is 
likely that the first, the Pyle Sarmatce , is the same with the 
Porta Ibericce, or Porta Caucausia, mentioned by Strabo, and the 
present pass, or valley of the Terek. The two latter, the Pyle 
Albanie and the Via Caspia , merely bestow two names on one 
place, which is the pass now called Derbent. But there was 
another, Porta Cwnana, and that lay farther westward. Pliny 
* Lib. vi. c. 11. 
