Instruction on the Fortification of Cities

Inside the city, the bastion rises 20 feetoriginal: "schuch" (shoes), a unit of measurement roughly equal to a modern foot. above the ground. Beneath this, the vaults should be strongly sealed, and the powerful arches should be constructed. However, toward point A, a corner remains for two half-vaults, providing a secret storage space. The vault arches should rise as semicircles from the foundation, 16 feet high above the ground on the inside. But the center point of the circle should be set into the ground, so that the base forms a square cross-shape; these shall be 8 feet wide, as mentioned before.

And the vaults should all remain freely underpinned [open underneath]. Each should also have round light and air holes in the keystonesoriginal: "schloffen", 5 feet wide, which can be covered on top of the bastion if necessary, so that artilleryoriginal: "geschos" can be moved over them. All such open holes should be provided for in such a way that heavy rain cannot flood into the vaults. Sufficient windows and light may be made in the side walls of these vaults. Also, two doors should be placed through the transverse wallsoriginal: "zwerch mauern" to provide entrance into the vaults.

Such a building is useful for keeping everything that belongs on the bastion inside it. But on top of these vaults, the bastion is walled flat and the entire bastion paved in such a way that all rain runs off easily. It should be arranged so that one can access the city wall from both sides of the bastion, and everything should be made so that nothing is in the way. The bastion should also be protected on all sides within the city with a flat, level ledgeoriginal: "abßatz", set 18 feet back into the bastion. Shots have little effect on this ledge, and on the inside, it should not be more than 4 feet high in front of the men, so that one can fire artillery over it in all directions.

And if it is deemed good, trenches with steps could be made in the arches of the vaults, in which one would stand more securely; this may also be used further on. Thus the rear part is prepared. But for the front part of the bastion, a barrel vaultoriginal: "küffen gewelb", literally a "tub" or "vat" vault. should be closed between the two round walls, all around from one side of the city wall to the other; internally 37 feet high above the ground and 7 feet thick, semicircular. And at the ends, where the embrasures for the heavy artillery are placed, the round wall should be hollowed out to a width of 15 feet, and as high as necessary. Above this, it should be vaulted as strongly as possible with two pointed archesoriginal: "geprochnen cirkelrissen", literally "broken circle-drawings," Dürer's term for the Gothic pointed arch., so that it may easily support a heavy load.

But further forward, where the embrasureoriginal: "schies loch" opens out, the wall does not need to be very thick, for it cannot be easily fired upon. Also, if the wall remained thick, one could not easily maneuver the large artillery forward. And so that the smoke may pass away, first, right under the vault, a round air and skylight hole should be made, three feet wide, through the thin walls.

But inside the thick wall, where it has been hollowed out, one should go upward with a semicircular hole through the vault and the ledge, and the semicircle should be strongly closed into the barrel vault at the peak. And if smoke still remains in the heights of the vault, one may lead a round hole three feet wide out through the middle of the vault behind every battlementoriginal: "schießzinnen". These should all be sloped upwards where they cannot be seen by the enemy; they require no covering, for they cannot be fired upon from the ditch. However, all these holes should be fitted with iron grates.

Each battlement should be prepared just like the others. Also, behind the small battlements, round holes should be led up through the vault as far as is necessary. But the ledge on the front part of the bastion should be led from the lower round wall up to the inner high round walls, perfectly level, all around from one side of the city walls to the other. And between this ledge and the barrel vault, everything should be solidly walled up. And this is particularly to be noted: when one wishes to fire in the flanking defenseoriginal: "streich wer", no shot should occur unless the muzzle of the gun is extended out through the embrasure window, for the powerful...