ons appear,--Mourrous (9760 ft.), on the border
of Hautes-Pyrenees, and the southern peak of Ossau (9465 ft.). The frontier
between France and Spain, for the most part, [v.03 p.0493] follows the
crest-line of the main range. Forts guard the upper valleys of the Nive and
the Aspe, along which run important passes into Spain. The general
direction of the rivers of the department is towards the north-west. The
streams almost all meet in the Adour through the Gave de Pau, the Bidouze,
and the Nive. In the north-east the two Luys flow directly to the Adour,
which they join in Landes. In the south-west the Nivelle and the Bidassoa
flow directly into the sea. The lower course of the Adour forms the
boundary between Basses-Pyrenees and Landes; it enters the sea a short
distance below Bayonne over a shifting bar, which has often altered the
position of its mouth. The Gave de Pau, a larger stream than the Adour,
passes Pau and Orthez, but its current is so swift that it is only
navigable for a few miles above its junction with the Adour. On the left it
receives the Gave d'Oloron, formed by the Gave d'Ossau, descending from the
Pic du Midi, and the Gave d'Aspe, which rises in Spain. An important
affluent of the Gave d'Oloron, the Saison or Gave de Mauleon, descends from
the Pic d'Orhy. From the Pic des Escaliers, which rises above the forest of
Iraty, the Bidouze descends northwards; while the forest, though situated
on the southern slope of the chain, forms a part of French territory. The
Nive, a beautiful river of the Basque country, takes its rise in Spain;
after flowing past St Jean-Pied-de-Port, formerly capital of French Navarre
and fortified by Vauban to guard the pass of Roncevaux, it joins the Adour
at Bayonne. The Nivelle also belongs only partly to France and ends its
course at St Jean-de-Luz. The Bidassoa, which is only important as forming
part of the frontier, contains the Ile des Faisans, where the treaty of the
Pyrenees was concluded (1659), and debouches between Hendaye (France) and
Fuenterrabia (Spain).

The climate of the department is mild and it has an abundant rainfall,
partly due to the west wind which drives the clouds from the gulf of
Gascony. The spring is rainy; the best seasons are summer and autumn, the
heat of summer being moderated by the sea. The winters are mild. The air of
Pau agrees with invalids and delicate constitutions, and St Jean-de-Luz and
Biarritz are much frequented by winter visitors.