122. The chronology of Ammianus is loose and obscure; and
Orosius (1. vii. c. 33, p. 551, edit. Havercamp.) seems to
place the revolt of Firmus after the deaths of Valentinian
and Valens. Tillemont (Hist. des Emp. tom. v. p. 691)
endeavours to pick his way. The patient and sure-footed mule
of the Alps may be trusted in the most slippery paths.