AXLE (in Mid. Eng. axel-tre, from O. Norweg. oxull-tre, cognate with the O. Eng. exe or eaxe, and connected with Sansk. dksha, Gr. a wv, and Lat. axis), the pin or spindle on which a wheel turns. In carriages the axle-tree is the bar on which the wheels are mounted, the axles being strictly its thinner rounded prolongations on which they actually turn. The pins which pass through the ends of the axles and keep the wheels from slipping off are known as axle-pins or " linch-pins," " liuch " being a corruption, due to confusion with " link," of the Old English word for " axle," lynis, cf. Ger. Lunse. AX - LES - THERMES, a watering place of south-western France, in the department of Ariege, at the confluence of the Ariege with three tributaries, 26 m. S.S.E. of Foix by rail. Pop. (1906) 1179. Ax (Aquae), situated at a height of 2300 ft., is well known for its warm sulphur springs (77°-172° F.), of which there are about sixty. The waters, which were used by the Romans, are efficacious in the treatment of rheumatism, 'skin diseases and other maladies.