B A S 



17 



B A S 



The guns mounted on the flanks of a bastion, by firing 

 along the ditch in front of the curtain and of the neigh- 

 bouring bastions, created a serious impediment to the pas- 

 sage of the enemy across the ditch in attempting an assault, 

 and it became necessary for him to silence that fire by a bat- 

 tery placed for the purpose in the direction of the ditch ; but 

 the establishment of this battery necessarily compelled the 

 defenders to augment the number of guns in their bastions. 

 To get room for these guns, engineers were induced to form 

 their bastions with a double and even a triple Hank on each 

 side, the flanks receding from each other, from below up- 

 wards, in the manner of terraces, towards the interior of the 

 bastion ; and, to prevent the enemy from dismounting the 

 guns in the lower flanks by other batteries raised in the 

 prolongations of those Hanks, it became necessary to mask 

 them by extending the rampart of the face beyond them, 

 and giving it a return towards the curtain ; this return was 

 frequently rectilinear, but generally in the form of an arc of 

 a circle, like a portion of a round tower, and the projection 

 with its return received the name of orecchione or orillon. 

 Besides masking the lower Hanks from the effect of any en- 

 filading, or lateral fire, it concealed one or more guns on the 

 upper flank from the fire of an enemy's battery directly op- 

 posed to that flank, while it permitted those guns to defend 

 the main ditch and the breach made by the enemy in face 

 of the collateral bastion. 



The desire of avoiding the exposure of the flanks of the 

 bastions gave rise to the practice of making them form a right, 

 and even an acute, angle with the curtain; but a better judg- 

 ment subsequently rejected this disposition, as the musketry 

 fire from the defenders of the flank was thereby liable to in- 

 jure the men stationed on the curtain. The lower flanks, 

 also, were eventually suppressed, because they contracted too 

 much the interior of the bastion to which they belonged ; and 

 because the enemy's fire, soon destroying the parapets of 

 those above, masses of brickwork fell among the defenders 

 below, and obliged them to quit their guns at the very time 

 that their service was most required. The nrilloru, moreover, 

 are now considered useless, as they contract the length of the 

 flank ; and the guns which they protect from a fire in their 

 front are liable to be dismounted by a fire from their rear. 



In what are called the second and third systems of Vau- 

 ban, the principal bastions are detached from the enceinte 

 by a ditch in their rear, and consequently the capture of 

 those works would not immediately compel the surrender of 

 the fortress. In these systems, a small bastion of brickwork, 

 closed by a parapet wall at its gorge, is constructed at each 

 of the angles formed by the polygonal wall surrounding the 

 place. The fire from the parapets of these tower bastions, as 

 they are called, would have a powerful effect in preventing 

 the enemy, after he has breached and stormed the great 

 baslions, from erecting batteries in them to destroy the in- 

 terior walls ; and, in order to preserve the artillery of their 

 flanks uninjured till the end of the siege, engineers placed 



it in casemates [see CASEMATE], from whence the guns 

 might pour a destructive fire upon the assailants when 

 crossing the ditch of the enceinte. In one of the systems 

 of Coehorn, each principal bastion is attached to the en- 

 ceinte, and contains an interior one for the purpose of pro- 

 longing its defence. At the shoulders of the former are 

 constructed towers of masonry, serving as orillons and con- 

 taining galleries whose front walls are pierced with loop- 

 holes, to allow a fire to _be directed along the interval 

 between the parallel faces o'f the two bastions. 



Bastions are now made either solid or hollow: that is, 

 either the interior is filled with earth up to the level of the 

 platforms of the guns, or it is left coincident with that of the 

 natural ground. Of the two methods, the former is generally 

 preferred, because it affords some facilities for the formation 

 and defence of interior parapets or retrenchments. In almost 

 every system of fortification the ramparts of the faces and 

 flanks of bastions have been made rectilinear on the plan ; 

 a few cases, however, occur in which the flanks have been 

 curved, with their convexity towards the interior of the work. 

 This seems to have been devised to allow room for a few 

 more men to fire over their parapets than a straight wall 

 could afford, and to prevent the distant batteries of the 

 enemy from easily dismounting their artillery by firing along 

 the interior side of the parapet. On some occasions these 

 advantages may be worth obtaining, but as the soldier placed 

 behind a parapet always fires nearly in a direction perpen- 

 dicular to its length, it is evident that the curved flank may 

 cause the lines of fire to tend towards the right or left of 

 the main ditch, and thus endanger 'the safety of the de- 

 fenders stationed in the neighbouring works. 



The desire of lessening the effect of what is called the 

 enfilading fire, or that which an enemy may direct along 

 the interior side of any parapet, has led Bousmard to give a 

 small curvature to the faces of his bastions, the concave part 

 being towards the interior ; but it is evident that, by this 

 construction, the lines of fire directed from the collateral 

 flank for the defence of the face, instead of grazing the latter 

 in its whole length, can only be tangents to the curve, each 

 line of fire meeting it in but one point. It is therefore pro- 

 bable that the injury inflicted on the enemy would be found 

 so much less than that arising from the usual construction, 

 as to neutralize entirely the advantage of the diminished 

 enfilade fire of the enemy. 



This last mode of firing would be most effectually pre- 

 vented by the formation of semi-circular bastions, detached 

 from the enceinte, in the manner lately proposed by Mr. 

 Bordwine ; but the ingenious author of that system is, in 

 consequence, compelled to abandon, in a great measure, the 

 advantage of having the exterior of his walls well defended 

 from those which are in collateral situations. The batteries 

 however which he proposes to raise in the interior of his 

 bastions cannot fail to produce a powerful defence towards 

 the rear, for the rampart of his enceinte. 



Pig. \. 



No. 207. 



[THE PKNNY CYCLOPAEDIA.] 



VOL. 1V.-D 



