Instruction on the Fortification of Cities

Now I return again to the ground plan. First, the doors that lead from the city into the bastion must be placed at the back, next to and outside of the two thinner walls that stand beside the thick cross-wall marked k. h. i. One of these doors should be made eight feet original: "schuch," a historical unit of measurement roughly equal to a foot high and five feet wide. In front of these doors, two ditches with two drawbridges should be constructed.

There are two ways the stairs may be led up onto the bastion: from the deep foundation or from the level of the pavement. However, from these two stairs, on each side, an entrance five feet wide and eight feet high should be made into the corners of the walls. After that, build the side stairs leading down on both sides to the round wall. There, make the passage to the flanking defenses original: "streychwern," structures designed to allow defenders to fire along the face of the wall wide enough so that those who are to defend have room. In those places where it is possible, light should be brought into the passages. Alternatively, one may build the stairs according to another design: namely, on both sides next to the stairs where the passages go into the corners of the side walls, lead the stairs thirteen feet deep down into both corners. There, leave a square landing original: "fletz" five feet wide, as also mentioned before in the elevation plan. After that, on each side wall that turns forward, let two more stairs be made, so that a square landing always remains between two sets of stairs. The steps should be five feet long, and the passage in front of the stairs should be five feet wide, until one reaches the space between the round walls on both sides. This bastion should also have strong, vaulted secret entrances and exits under the earth leading out from the city. These same entrances should be covered by houses so that they are hidden. One may also have many secret storage rooms in this bastion for treasures and other necessities required by great Lords. These passages to the secret vaults should not be wider than three feet, but the vaults themselves should be made as wide as the space between the walls allows. Do not build any vaults directly under the main walls, except where the narrow passages go through them, as there is enough other space available for that purpose. I will indicate these passages in the following ground plan with dotted lines, and where the vaults are to be made, I will place small crosses in the ground plan.

Regarding the flanking defenses, however, one should build eight vaults between the cross-brace walls in the front round wall. Leave the entire width between the brace-walls as open space, and carve out the upright inner walls on both sides with a flat circular arc, like a broken vaulted arch, so that the point or sharp edge faces toward the ditch. Yet, ensure that the wall remains two feet thick at that same spot. Then, the gun ports original: "schieß löcher" are made through it, as necessity requires for large or small firearms original: "püchsen," referring to early cannons or heavy guns. The outer corners should be rounded off with a circle so that one can fire toward both sides, as there will be enough room inside to move the guns back and forth. Secure the stones inside on both walls like vaulted arches, and a circular band should be closed around the gun port so the wall stands with strong reinforcement. If the gun ports must be wide for heavy artillery, one may make shutters of thick wood reinforced with iron to place in front, with iron bolts behind them, and make narrow gun ports through them for small firearms to defend from. These shutters will stop hand-gun fire, but for the large artillery, the shutters must be open. In the following flat ground plan, a vaulted arch is shown in the thick round walls, indicating how it should be built over each defensive position. It also shows where the vent original: "schlot," a chimney or flue to allow gunpowder smoke to escape should rise, so that the previous elevation plan and this one agree in all things. The walls of the small ditch shall be made thus: first, draw the outermost line of the sloping walls of the bastion, which in the elevation plan hangs down from point i....