Note 001
They were originally nine or ten thousand men (for
Tacitus and Dion are not agreed upon the subject), divided
into as many cohorts. Vitellius increased them to sixteen
thousand, and as far as we can learn from inscriptions, they
never afterwards sunk much below that number. Lipsius de
magnitudine Romana, i. 4.
Note to Chapter 5 of DECLINE & FALL by Gibbon