Instruction on the Fortification of Cities

Furthermore, if one wishes to build upward from the previously established foundation and ensure the construction stands correctly, one must also lay out the upper plate The "upper plate" or "upper plan" refers to the horizontal dimensions of the fortification at its highest level. as it will be enclosed, and indicate therein all the masonry as it is to be tapered veriungtthe architectural process of narrowing a wall or structure as it rises to increase stability and provide a defensive slope. This is done as follows: first, draw the line d-e and through it the cross-line creuclinia primary horizontal or transverse reference line in a geometric drawing f-g. Set points f and h as before, and move point i on line g-h fifteen feet original: "schůch"; a historical unit of measurement approximately equal to a modern foot. backward toward h.

Then, using a compass, draw a circle from point f through the moved point i on both sides until it touches two straight lines. From there, proceed on both sides backward with two straight lines at right angles, forty-five feet long. There, place the two letters l and m as before, and join them together with a line. In this way, the upper plan or ground layout is enclosed according to its intended length and breadth. The building will be thirty feet narrower at the top than at the bottom of the foundation along the cross-line f-g; it will also be approximately thirty-five feet shorter along the line d-e than at the bottom of the foundation.

How the straight and curved walls should be proportionally tapered into the upper plan, matching the lower foundation, is determined by the following artful method. Take all the points of the curved wall thicknesses and the widths of the fields In this context, "fields" refers to the open spaces or bays between the supporting walls. between them from the lower foundation along the cross-line f-h-g, with their respective letters, and transfer them all onto a transverse line zwerchlinia horizontal baseline used for transferring measurements between different parts of a technical drawing. Just as the front beginning of this line is an i, let its rear end be l-m.

Next, draw a straight vertical line at right angles upward from point h as far as necessary. From the narrower upper plan, take the length of the cross-line with the points and letters i-h and the length behind it to the end of the point between l-m. Place these on a line, setting point h upon the vertical line that was drawn up from the lower point h of the foundation plan, so that it is parallel to (or equidistant from) the lower line i-h and l-m.

Afterward, draw straight through i-i upward to the vertical h-h; there, place an o. Then, place a straightedge richtscheydta precision wooden or metal tool used for drawing straight lines or checking the flatness of a surface with one end at point o and let it remain fixed there. Move the other end to all the points of the transverse line i-h of the lower plan. From all of these, draw straight lines toward point o until they reach the upper parallel line i-h. By this method, the upper line i-h is divided proportionally to the lower line i-h. Through this, all upper walls and the fields between them are made narrower than they are at the bottom in the foundation, according to the proper order.

Following this, place the straightedge at the two ends l-m and l-m and draw a line through them until it meets the line o-h; there, set a point p. Then, place the straightedge with one end at point p and let it remain fixed; with the other end, move it from point to point on the lower foundation line between h and l-m, and draw straight lines from all of them toward point p until they reach the upper transverse line h and l-m. Thus, it will also be divided exactly like the lower one, yet every part will be smaller by the correct measure than the parts of the lower line.

Now, take the upper lines i-h and l-m with all their points and transfer them into the upper plan onto the cross-line; place h upon h and i upon i and set the points l-m. From these, draw all the circular walls, the center of which is point f. Thus the widths of the fields between them are found. Also, draw the straight walls from their respective points. In this manner, the upper plan is tapered and correctly divided. To understand this all the better, I have drawn the figure following this.