The Gelt is a small tributary joining the Irthing shortly before the latter falls into the Eden.
Polybius (vi. 24) tells us that in the Roman army of his day a vexillum or manipulum consisted of 200 men under two centurions, each of whom had his optio. Vegetius (II. 1) confines the word vexillatio to the cavalry, but gives no clue as to its strength.
On this inscription see Huebner, C.I.L. vii. 1. A drawing will be found in Bruce's 'Handbook to the Wall' (ed. 1895), p. 23.
The name Cilurnum may be connected with this wealth of water. In modern Welsh celurn = caldron.