The waters of the northwestern slope of the southern Cevennes drain into the Tarn either directly or by way of the Aveyron, which rises in the outlying chain of the Levezou, and, in the extreme south, the Agout.
It is unusual in having a tarn adjacent to the trig pillar.
After holding a subordinate office (1876) in the department of public works, he became successively prefect of the Tarn (1882) and the Haute-Garonne (1885), and then returned to Paris to enter the ministry of the interior.
Jaures was again elected for the Tarn.
Its chief rivers are the Lot in the north, the Aveyron in the centre and the Tarn in the south, all tributaries of the Garonne.