A leathern bag, containing about 50 lb. of powder, should be hooked upon the gate, as near the centre as possible (or be laid on the ground, close to the bottom of the gate, and tamped with sods, &c.), and be fired by means of a piece of portfire, or match, passed through a hole in the bottom of the bag.
FORTIFICATION.
Offensive fortification is the art of conducting a siege.
Defensive fortification comprehends military architecture, and is the art of securing, or protecting a place by works, to resist a siege.
Natural fortification consists of obstacles, such as marshes, mountain passes, &c., which are found in some countries, and should be taken advantage of to impede the approaches of an enemy.
Artificial fortification comprises those works which are constructed to defend a place.
Permanent fortification is the art of putting towns, &c., into such a state as at all times to be prepared to resist the attack of an enemy.
Field fortification is the method of fortifying a camp, or position, buildings, &c., and it includes the construction of redoubts, entrenchments, &c. Works of this nature are considered as temporary.
Irregular fortification is the art of fortifying a place of an irregular figure, situated where the country does not admit of giving to the several works their due proportion according to rule.