, in the modern fortification, a large mass of earth at the angles of a work, connecting the curtains to each other; and answers to the bulwark of the ancients. It is formed by two faces, two flanks, and two demigorges. The two faces form the saliant angle, or angle of the bastion; the two flanks form with the faces, the epaules or shoulders; and the union of | the other two ends of the flanks with the curtains forms the two angles of the flanks.

Solid Bastion, are those that are entirely filled up with earth to the height of the rampart, without any void space towards the centre.

Void or Hollow Bastion, has the rampart and parapet ranging only round the flanks and spaces, so that a void space is left within towards the centre, where the ground is so low that if the rampart be taken, no retrenchment can be made in the centre, but what will lie under the fire of the besieged.

Regular Bastion, is that which has its due proportion of faces, flanks, and gorges.

Deformed or Irregular Bastion, is when the irregularity of the lines and angles throws the bastion out of shape: as when it wants one of the demigorges, one side of the interior polygon being too short, &c.

Demi Bastion, or Half bastion, also otherwise called an Epaulment, has but one face and flanlt.

Double Bastion, is when one bastion is raised within, and upon the plane of another baslion.

Flat Bastion, is one built in the middle of the curtain, when it is too long to be defended by the usual bastions at the extremities.

Composed Bastion, is when the two sides of the interior polygon are very unequal, which makes the gorges also unequal.

Cut Bastion, is that which has a re-entering angle at the point, and is sometimes called a Bastion with a Tenaille, whose point is cut off, making an angle inwards, and two points outwards. This is used when the saliant angle would be too sharp, or when water or some other impediment prevents it from being carried out to its full extent.

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Entry taken from A Mathematical and Philosophical Dictionary, by Charles Hutton, 1796.

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