The Fortifications

fense of 180 paces, because the said parts R S are equal all around their circumference, and the distance that must be from the flank of one bastion to the point of the other H V, which is the length of the said defense, must be measured and proportioned with the proposed scale to the members and the entire body of the fortress. We will begin with the bastion, as the head of that body, which is formed upon the angles in this way, that is: Take from the scale the length of thirty paces, or ninety braccia, and set the point of the compass upon the angle L, and with the other point, note the points G H on each side, which will be the width of the throat of the bastion, or its interior angle L H G. And the same will be done upon all the other angles of the bastions. Then, taking a small square, one will draw the line H I, at least thirty paces long, so that it falls upon the said point H and makes a right angle

The interior angle of the bastion, how it is made.

upon the line, or curtain H N, and the same will be done at the other flank G M, and upon all the other interior angles of the bastions, always drawing these first lines with a lead pencil so that they can be corrected when an error is made in drawing them, especially to remove those that should not remain described with ink once the drawing is completed, as will be seen by the dotted lines. And to form the said bastions, one must always take the defense of its fronts furthest

Defense of the bastion, where it should be taken.

from the flank that one can, that is, in the length of the curtain, and this will be done to increase said defense, because by being taken at the middle of the curtain (as one can still do in the proposed octagon, and even more so in the others that follow), such a part of the curtain (that is, its interior plaza) will come to perform the office that the flank performs, especially with its cavalier in discovering and defending the moat with the front of the bastion. Nevertheless, to show how much difference there is in taking said defense from the third or the middle of the said curtain, we will now form its bastions taken from the third; that is, each curtain will be divided into three parts, as is seen by the N H into P O. Where, placing the ruler upon the point O, and at the end of the flank line I, one will draw another that goes to infinity, and similarly from the other side, drawing the Z M, and where it intersects above the first Q, there will be the inferior angle, or the point of the bastion M Q I. And to form the shoulders, or orecchioni ears/revetments, that come to cover that part of the flank where the artillery must stay, one will divide the line M G (which we said to be thirty paces) into three parts; two of which will be given for the thickness of the shoulder, which will be M Y, and one to the width of the flank Y G, and finally, one will form (to close the bastion) the half-circle X &.

Shoulder and front of the bastion, how it should be formed.

But by taking the defense from the middle of the curtain, as is seen by V T, the angle K is formed; although somewhat more acute than the first one, it could for that reason be tolerated, the counterscarp being cleared by the flank, which in the defense taken from the third cannot be, as is seen by the symbol ♒ ♂. This moat must be formed in this way: that is, let it be made wide,

Defense of the counterscarp, and its considerations.

facing the angle Q of the bastion, thirty paces, which will be the symbol ♌, and being able to make the counterscarp ♒ ♂ be swept by the flank, one will draw it to such straightness; but not being able to, one will at least make it parallel to the front Q &, so that the part M ♊ is not narrower than Q ♌, which would be a much greater imperfection than not having such a part discovered, being guarded by the other plazas and cavaliers above.

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