36 COUNTERMINING. chap, overwhelming them by an explosion of only . — moderate strength. At length, on the 3d of February — the fourth day after the one when the miner's approach was first heard — Colonel Todleben unleashed a cam- ouflet ( u ) which left undisturbed the whole sur- face of the ground overhead, but tore its way into the gallery where the French had been heard, killing two of their men as it passed, and visibly rinding its issue in the open air through ground behind their third parallel, thus showing him where lay the entrance to their system of mines. The French of course then understood that their project of surprising the enemy by a mine to be sprung from ground under his Flagstaff Bastion had been discovered and baffled ; but it occurred to their chief engineer that they might still draw advantage from the system of under- ground approaches on which they had bestowed so much labour, because it would enable their miners to open up by explosion a line of craters half-way between their foremost trench and the counterscarp of the opposite bastion, and he hoped that the ground, when so broken, and therefore affording some cover, might be made the beginning of a fourth parallel. He therefore by means of explosion threw up, to begin with, one crater of moderate size ; * but it was seized, was crowned, was definitely held by the Eus-
- Evening of the 7th of February. — Niel, p. 146 ; Todleben,
p. 619 et seq.
