2?2 SERVICE OF ARTILLERY

80. The countermines under the outworks or ditch, mustbe attacked before the third batteries can be erected.

If the profile of the attacked work be narrow, as that of acounter-guard, for example; two or three holes, distant fromeach other about 50 or 60 feet, should be made near the foot ofthe revetement by the battering guns ; sloping even for thatpurpose, if necessary, the embrasures and the top of thecounterscarp : the wall being thus pierced and the descentand passage across the ditch completed by the sappers, theminers should be introduced into each hole, to drive a shaftinto the terreplein, equal in length to the height of the wall;and having made branches to the right and left, they shouldmake a chamber at the extremity of each, to destroy the sur-rounding countermines. If they meet with a branch orgallery, they should endeavour to chase the besieged from itby throwing in fetid combustibles; and in the mean time pre-pare and charge a chamber or two to destroy these counter-mines and shake down the casemates: while one party ofminers is thus employed, another should explore the commu-nications leading to the countermines under the glacis fromthe attacked outworks, in order to drive the besieged fromthence by force or other means.

These operations are carried on under cover of an incessantfire of mufquetry from all the lodgements that bear uponthe ditch, to check the besieged in any attempt to destroy theepaulment, or disturb the miners.

8t. If the attacked work be very spacious and the be-sieger under the necessity of erecting batteries at the gorge ;after having destroyed the countermines under the breach(8o), he must effect a lodgment in the gorge by assault;and then by sinking shafts endeavour to cut off the commu-nications between the countermines and the body of theplace: for this purpose the direction given (73) for the attackof the countermines under the glacis may be successfullyapplied. While this is going forward, he should endeavourby means of the shafts funk upon the capital, or of the coun-termines he has got possession of, to penetrate into the gal-leries under the gorge of the work, and totally expel thebesieged, ascertaining by these means the security of his bat-teries.

82. From these premises it may be inferred;

t. That to attack a place with two stages of coun-termines, there must be a large corps of miners and

great