2^8 SERVICE OP ARTILLERY

for the principal galleries, either by finking- shafts or makingslopes in the glacis ; and the instant they have discoveredone, they make an opening to turn the water of the canalinto it.

73. If the countermines cannot be inundated, the readiestand least dangerous way is to attack them at the entrance,which is known to be in the faliant and re-entering anglesof the covered way, and destroy them > the besieged willbe then prevented from penetrating into those under theglacis. To this end, the sappers must effect a lodgmentBetween the faliant angles of the covered way and the placesof arms : when these lodgments are effected, the squads ofminers must as expeditiousty as possible sink shafts a littlelower than the countermines, from 40 to 60 feet distantfrom'each other, and carry ,crl two branches parallel to thecounterscarp and a return at the extremity of each to formthe chambers ; which must be well loaded, that the adjoin-ing galleries and branches may be entirely overset by the ex-plosion. If, in the course of this work, they meet with agallery, they must immediately break into it, and throw inquantities of fetid Compositions to make it impossible for thebesieged to re-enter, that that they may finish their mineswithout molestation ; they should be sprung as soon ascompleted.

When the besieged destroy any of the shafts by springingA Countermine, others should be immediately funk at such adistance from the former, as not to pass through any of theearth shaken by the explosion ; since the labour of the minersin working among loose earth is endless, for the sides crum-ble down as fast as the excavation is made. »

Supposing these shafts to be completed and the chamberscharged, other shafts may be funk in the lodgments on thecrest of the glacis, particularly on the capitals of the works,for the purpose os more easily exploring the enemy’s galleriesunder the glacis and entering them, when the communica-tion between them and the body of the place is cut off byspringing the mines under the covered way; and whenby means of these straffs a gallery is discovered, a party ofarmed miners should examine'whether there be a possibilityof the besieged returning into it. If it be possible, theyshould penetrate beyond the points corresponding to theattack, and throw in some fetid combustibles, taking care toretire time enough to save themselves from suffocation; and

then