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This is a hand-edited transcription produced from Scans by Bayerische Staatsbibliothek using OCRmyPDF and translated with GPT4 via ChatGPT

CHAPTER FIVE

WHEREIN THE GEOMETRIC DEFINITIONS ARE INCLUDED Applied to the Skill of the regimen of the Sword

In the clarification of the proper and necessary terms for understanding the regimen of this Art and its teaching, we have defined that the science of the Sword, commonly referred to as the Skill of Arms, teaches how to deliver a blow and defend against one from the opponent, whether with the Sword alone or with the other Weapons that usually accompany it.

The means by which this is sought are movements, both of the body and of the arm and Sword. All these movements together comprise what they call a tactic; thus, we define or describe the treta in the following manner.

A tactic is a combination of movements from either of the two combatants, directed at one’s own defense and the offense of the opponent.

The tactic that is formed from knowledgeable and suitable movements to achieve the intended goal will be perfect or true; and the tactic that lacks the necessary requirements for its perfect formation will be called false.

The way we must judge the perfection or imperfection of the treta is to examine all its components, which are the aforementioned movements.

We also defined that movement, according to Aristotle in the third book of Physics, is an action of the mover upon the moved thing.

To grasp the understanding of this action in Weapons, we need to first know the agent or mover, which is the Swordsman or his opponent, and the moved thing, which is the Sword, and in how many ways he can move it, along with the other parts of the body, in order to form some treta. Then, immediately, we must see the harmony and discord that may exist between these movements, both of the body and its parts.

Aristotle in the third book of Physics, speaking of movement, says that it seems to belong to the category of the continuous; and the continuous properly pertains to continuous quantity, whose species are Lines, Surfaces, and Bodies. Thus, it seems that Aristotle with these words wanted to suggest that the speculation of movement pertains to Geometry, the key to the mathematical sciences, whose role is to discuss continuous quantity and speculate its properties. This is clearly implied, since movement and quantity are so intertwined that we find nothing that belongs to quantity that can be moved without its movement causing a physical or imaginary quantity; for if it is a point that moves, its movement will cause a straight, circular, or mixed line, depending on the nature of its movement.

If it’s a line that moves laterally, with its movement, it will cause a flat, spherical, or mixed surface, depending on the nature of the line and its movement.

If it’s a surface that moves, it will produce a body, containing flat, spherical, or mixed surfaces, or parts of some and parts of others.

If it’s a body that moves from place to place, it will create a body of a different shape than it had.

The first three considerations, of the point, the line, and the surface, are very necessary in Fencing, as shown in its place; the last, which pertains to the body, is not used in this science because although the bodies of the two combatants must necessarily move to form their tactics, we do not consider the bodies that cause the movements, but that they move along certain straight or curved lines, according to the form of the movement. In this, they imitate the astronomers, who, although they consider those celestial bodies moving within their orbits, to regulate their movements they rely on lines, not on bodies. The same is done by those who deal with navigation; to regulate the movement of the ship on the surface of the waters, they rely solely on lines, which they call bearings (rumbos).

And given that all who have dealt with movements, both violent and natural, have done so under the speculation of continuous quantity, it will be good for us to imitate them in this. For if, through these imaginations, they have been able to regulate the movements of the stars in the heavens and the movement of ships in the water, it won’t be much to hope that, using the same means, we can regulate the movement of the sword in the air and the movement of the body on the ground.

This being so clear that it does not admit controversy, we will put all our effort into finding the way to facilitate the Art of Fencing through Mathematics, showing the use of some lines, surfaces, and bodies, which will serve us as a guide and north star for its perfect understanding. But before we can do so, we define some definitions related to Geometry, even though in the proper terms we have already specified a great part of them; but without figures, because of the complications that ensued. And in these definitions we now declare, it’s necessary to include them, so that later we can show the fencer their application in the Art of Fencing.

1. A Point (according to Euclid, Defin. 1. Book 1. of his Elements) is that which has no part.

Definition of the Point.

 

Among mathematicians, two types of Points are recognized: one is Mathematical or imaginary, an essence without quantity, abstracted from matter, and solely objectified by the understanding; the other is Physical, Real, or material, which, however small, can always be divided into divisible parts. This is marked with the letter A in figure number 1.

In the Art of Fencing, we also consider two types of Points: Physical ones, which are considered at the tips of Swords; and imaginary or Mathematical ones, considered at the intersection of certain imaginary lines, both on the ground plane (understood as the Floor) and on the bodies of the two combatants, or in the Air, with the lines we consider passing through the arms and Swords of the two combatants.

2. A Line (according to Euclid) is a length without breadth. Just as the Point is considered in two ways, one Physical and the other Mathematical, the Line will also be either Physical or Mathematical. For if the Line, according to Plato, is the flow or movement of the Point, if the Point is Physical, the resulting Line will be Physical; and if the Point is Mathematical, abstract from matter, the Line will also be Mathematical.

Definition of the Line.

 

A straight Line is the shortest extension from one Point to another, the smallest of all lines that have the same endpoints, or that which lies evenly between its Points. For example, the Line B.C., which resulted from the straight movement from Point B to Point C. The limits or ends of the Line are Points, like B and C, and are seen in figure number 2.

Of the Straight Line.

 

In the Art of Fencing, we consider the Sword, Dagger, and Montante, or their edges, as a Physical line. Whenever the tip of the Sword moves to a place where it can leave a mark or trace of its movement, such as on the ground, or against a wall, or on the body of its opponent, the line it causes with its movement will be Physical. And whenever it moves in the Air, even though strictly speaking it seems to be Physical, we will call it imaginary because it falls not under the sense of sight but under imagination; and such a line will be straight, circular, or mixed, according to the nature of the movement.

3. A curved Line is one that forms an Arch, and is not straight, as demonstrated by the letters D. and E. in figure number 3.

Of the Curved Line.

 

In the Art of Fencing, we consider it when the arm bends without making an Angle at the cut, and when the body is positioned in an arch-like manner, leaning forward or to the sides, making the Arch in depth; it is also considered on the ground plane, and particularly in the compasses, which derive their name from it.

4. A mixed Line is one that is neither straight nor circular. For example, the line F.N. is straight, and N.G. is curved, as seen in figure number 4.

Of the Mixed Line

 

In the Art of Fencing, it is formed with the Sword and arm when the arm bends without making an Angle at the cut; it is also seen on the ground for mixed compasses and for the concluding movement, representing it by the mixed compass of transversal and curved.

5. A wavy, tortuous, or Eliac Line is one that snakes like a River or serpent. It is divided into two types: one almost straight, and another that is winding; the almost straight one is H.I. and the winding one is K.L. in figure number 5.

Of the Wavy Line.

 

In the Art of Fencing, H.I. is considered when the tip of the Sword, with an accidental or strange movement mixed with slackening movements, describes portions of curved lines underneath the other Sword, to one side and the other; and K.L. is considered when also with an accidental or strange movement mixed with others, it forms curved lines without interruption in its course, or even when using the Sword to encompass the opponent’s Sword to restrict its freedom.

6. A spiral or volute Line is one that, in the manner of a snail, wraps around some columnar body without returning to where it began, similar to the turns the Sun makes between the Equator and the two Tropics. It is marked with the letter M in figure number 6.

Of the Spiral Line

 

En la Deſtreza ſe conſidera en muchas partes, y propoſiciones, como quando ſe forman las dos generales, flaqueza encima, y debaxo de la fuerza; y quando la Eſpada del Dieſtro figue à la de ſu contrario por la parte de adentro vnitivamente, haſta haer movimiento de concluſion, quedando hiriendo, formando el Angulo mixto: y tambien quando eſtando pueſto el atajo por de fuera en el extremo propinquo en la Eſpada del contrario, ſi eſte levantare el brazo, y guarnicion, incluirà, y rodearà el Dieſtro las Eſpadas por aquella parte, haſta dexar la contraria debaxo de ſu brazo derecho, y la fuya hiriendo por encima de la juriſdiccion del brazo, haziendo al miſmo tiempo movimiento de concluſion; y aſsi eſta linea eſpiral ſe puede formar tomando la Eſpada por la parte de adentro, y la de afuera.

7. Parallel straight lines are those that, extended infinitely and on the same plane, never converge. They are represented by the letters N.O. and P.Q. number 7.

Of the straight lines

 

In fencing, they are formed when choosing the middle proportion, according to the Art, to immediately set a block on the inside; they are also considered in many other propositions and cases, both on the lower plane and on the upper one. In the bodies of the combatants, the Vertical, Collateral, and Diametrical lines are parallel.

8. Converging lines are those that, drawn through a plane, converge, making a section, segment, or cut, as represented by the letters R.S. and T.V. that converge at X. number 8.

Of converging lines

 

In fencing, they are considered when two lines or swords join or one is subjected to the other; also in other propositions. These two lines are said to be non-parallel.

9. Elliptical line is similar to an oval figure, divided into two parts, with a Diametrical line, as shown by the letter Y. number 9.

Of the ellipse

 

In fencing, we consider it in the human body, in the Arch made with the bulk of the body and chest, because the back is almost flat.

10. The hyperbolic or parabolic line is the one that resembles or is similar to a mountain, or more precisely to a pile of wheat. It is represented by the letter Z. number 10.

Of the hyperbolic line

 

In fencing, it is used to describe the steps and is considered in the journey, both of the curved step mixed with trepidation and strange, and of the transversal one, mixed with trepidation and strange; and also in some revolutions made by the sword in the air.

11. A circular line is one that results from the movement of a point when it always moves at an equal distance from another point that is immobile: for example, if point A is fixed and point B moves always at an equal distance from point A, the line that results from its movement will be called circular, number 11.

Of the circular line

 

In fencing, these circular lines are formed with the arm and sword, and we also consider them in the upper and lower planes, as will be explained in the application we will make of them later.

12. Angles are the inclination of two lines that meet at a point and are not straight.

Definition of Angle

 

13. A Planar rectilinear angle is one that is contained by two straight lines, converging as marked by the two Swords C.E. at point D. number 12.

Definition of Angle

 

In fencing, we use the most generalized kind of Angle, as will be explained in each species: and we consider the rectilinear one anywhere the two Swords intersect or touch the Horizon plane; and also in the lower one it is caused, both in the lines we consider in it that serve us as directions, and when the transversal steps are given, mixed with trepidation, and strange; and in the imagined lines from one shoulder to the other of the fighters. A planar rectilinear angle is also formed for some propositions.

14. Planar curvilinear angles are those composed of curved lines, as marked by the letters D. in one, E. in the other, and F. in the third, in the figure number 13.

Curvilinear

 

In fencing, we consider them when fighting with double weapons, and also in the lines that in the lower plane describe the feet for different steps.

15. A mixtilinear angle is one that results from the touch of a straight line and a curve, as marked by the letters L. and N. that converge in M. number 14.

Mixtilinear

 

In fencing, when the arm is curved, and with the straight line, which is considered in the chest (whom we call of contingency) they constitute an Angle on the right side, or with the arm, and sword, constituting it in the grips: we also consider it in the lower plane for mixed steps.

16. A right angle occurs when a straight line, falling upon another straight line, makes the angles on either side equal to each other: each of the angles is called right, and the line is said to be perpendicular to the other: for example, the line C.D. is said to be perpendicular to the base A.B. and makes the right angles, number 15.

Right

 

In fencing, it is considered when the right arm is not affirmed, as it arises in the body, without participating in any of the extremes from top to bottom, to one side or the other, the body being the line A.B. and the arm, and sword C.D. and these right angles are also considered and formed, both in the lower plane and in the touching of the swords.

17. An obtuse angle is greater than a right angle, as the sword rises from the letter C, which was considered a right angle, to the letter B, num. 16.

Obtuse

 

In Fencing, it is considered when the arm raises to the high straightness directly, or leaning together to either side; in a way, that the arm and body are not parallel to the Horizon plane, as C.D. indicates, but are found as demonstrated with D.B.

18. An acute angle is less than a right angle, as the line of the arm and sword drops from the letter C.D. where it was considered to be right, to the letter B, where it is acute, num. 17.

Acute

 

In Fencing, low postures are made with it; so, the arm is not fully united to the body, nor the hand and Sword to the thigh, as indicated by the letter B.

19. Surface is that which has only length and breadth, and in the same way that we consider the line caused by the movement of the point; we also consider the Surface caused by the movement of the line: and as the line is divided into three differences, straight, circular, and mixed, according to the nature of the movement of the point; the Surface will also be divided into three, according to the difference in the movement of the line, which is called flat, spherical, or mixed, and the ends of the Surface are lines.

Definition of the Surface

 

20. A flat surface is one that is equally between its lines and is caused by the lateral movement of the straight line when it moves equally: for example, let’s suppose that the line A.B. moved entirely from where it is, to D.C. equally, and directly by the shortest path, it will have caused a flat surface, bounded by four straight lines A.B.-A.C.-C.D. and D.B. and we call this type of Surfaces flat, for brevity.

Of the Flat Surface

 

In Fencing, this Surface is demonstrated in the lower plane, and also in the upper one, imagining a contact line from one combatant’s shoulders to another’s, for when they face each other, the bodies are squared, and the Swords in parallel lines, pointing the tips to the left shoulders, and considering in them a point of contact, will have formed a flat Surface.

Also, the surfaces, if composed of curved lines, like the arches of Buildings, we will call them concave on the lower part, which is indicated by the letter A, and convex on the upper part, where the letter B is, as shown in figure number 19.

In Fencing, this surface is considered when the body leans extremely forward, or backward, or to the sides, and also in the description of curved compasses, which if the foot left a trail, this surface would be perfectly formed.

Also, the straight line would cause a flat surface, if, with one end fixed, the other moved around it; as in the following figure, which is called a circle, and is defined by Euclid in this way.

21. A circle is a figure contained by a single line, which is called circumference, indicated by the letters A.D. to which, from a point within it, all the lines that go to the circumference, being straight, are equal to each other; and this point is called the center, as indicated by the letter B. in number 20.

Definition of the Circle

 

In Fencing, we consider different circles: such as the upper, the lower, common, particular, and others, according to the positions of the combatants, and the proportions that are made, as we will explain later.

22. The diameter of the circle is a line, passing through the center, terminates on both sides in the circumference, and divides the circle into two equal parts, as indicated by the letters A. and D. and half of the Diameter is called the Radius, number 21.

Of Diameter

 

In Fencing, we consider the line of the Diameter, both in the lower plane and in the upper one, and in the body of the combatant.

23. A semicircle is the same as half a circle, being a figure contained by the Diameter, and half of the circumference, indicated by L.Y. number 22.

Of the Semicircle

 

In Fencing, we consider it, both in the formation of many tricks and in the execution of some blows.

24. A portion of a circle is a figure contained by a straight line and part of the circumference, greater or smaller than half of it: it is called a larger portion or segment, indicated with A.B. and a smaller portion or segment, indicated with C.D. number 23.

Portion of Circle

 

In Fencing, we also consider these portions for the formation of strategies and execution of strikes, depending on the path that the Sword follows, as everything is manifested in the Treatise of strategies, and in many other propositions, where its application will be seen.

25. A quarter of a circle is one of the four parts into which the entire circumference is divided, indicated by the letters A.B.C. in number 24.

Quarter Circle

 

In Fencing, it is useful when, by taking the opponent’s Sword from the inside, one strikes with a thrust in the right vertical: and when taking it from the outside, one strikes above the Sword in the Diametral of the chest: this quarter of a circle is also considered in the formation of other strikes and in the lower plane, as the common circle is divided into four, as is the one considered in the man’s chest.

26. Concentric circles are those described with only one center, like A. and B. that are described with the center M. num 25.

Concentric Circles

 

In Fencing, these circles are evident, as the maximums include those that are caused by the revolution, which is caused by the divisions of the arms, and Swords, and all are concentric; which serve as a guide or compass, both to regulate the measures of the means of proportion, as proportioned, giving them a fixed quantity to the compasses, as will be explained in its place.

27. Eccentric circles are those that have different centers, and the larger one includes the smaller one in this figure, because the larger one has the point A. as its center and the smaller one has the point B. which interval is included by the larger one, num. 26.

Eccentric Circles

 

In Fencing, they are considered when the Swords, and bodies are unequal, as the circle described by the larger one, and with the larger one, will include the one described by the smaller one: and it is also considered in the lower plane, as the circle, to whom we give the name of Maximum, will include the common one, which is imagined between the right feet of the combatants, and they have different centers.

28. Tangent circles are those that, touching at one point, do not intersect, like the circles A. B. of number 27.

Tangent Circles

 

En la Deſtreza ſe manifieſtan eſtos circulos en los Orbes, que de las diviſiones de los brazos, y Eſpadas de los combatientes, conſideramos en el plano inferior; pues el Orbe, ò ciruclo que deſcribe el Dieſtro con ſu punta de Eſpada, es contingente al que deſcribe el brazo del contrario; y à eſte reſpecto en las demàs diviſiones de la Eſpada, como ſe verà en ſu proprio lugar.

These circles are also seen with perfection in the formation of the vertical cut and reverse cut, which in their execution touch in the vertical middle of the Zenith E., going through the forehead to the chest, and to the ground F., as shown in said number 27.

Also, the straight line touching the convexity of these circles is called the line of contingency, or tangent, marked by the letters C.D. of the same number 27.

Any straight line drawn within the circle, which is not a diameter, is called a Chord, like the A.B. of figure 28, and the portion of the circumference it subtends is called an Arc, like the C.D., and the Line that bisects the Arc and the straight line is called the Sagitta, marked by the E.

Before entering the declaration of the other Surfaces, we will discuss some necessary figures for their understanding, which are caused by the flat Surface; and since we talk about figures every step, we will put here the definition given by Euclid book 1. Defin. 14. for them.

A figure is the surface contained beneath one or many boundaries; one with a single boundary is a Circle; one with two boundaries is a Semicircle, or a larger or smaller segment; one with three boundaries is a Triangle; one with four, a Quadrilateral, etc.

Definition of Figure

 

Rectilinear Figures are those contained by straight lines. Trilateral Figures are those contained by three straight lines.

Rectilinear and Trilateral Figures

 

Multilateral, or Polygonal Figures, are those contained by many straight lines.

Multilateral

 

27. A Triangle is a closed surface with three lines and three angles, it takes its name according to the lines and angles; thus, when it consists of straight lines, it is called a Rectilinear Triangle, if of curved lines, Curvilinear, and if of two straight and one curved line, Mixed, as was said of the angles.

Definition of Triangle

 

There are three kinds of Rectilinear Triangles, which are named by the length of their sides, or by the opening of their angles, in this way.

Rectilinear

 

Among the Trilateral Figures, the Equilateral Triangle is the one contained by three equal straight lines, as demonstrated by the letters A.B.D. in figure num. 29.

In Fencing, we use it for many things, both for self-defense and for offending the opponent; particularly for the perfect attack on the inside, considering one of its sides as the arm, another one as the line of contingency of the chest, and the other imagined from the hilt of the Sword, to converge on the left shoulder.

28. An Isosceles Triangle is contained beneath two equal sides and a base that is unequal, as appears in the figure, because C.X. is equal to X.R. and unequal to both sides C.R. as shown in number 30.

Isosceles Triangle

 

In Fencing, it is important in many cases, applying it more or less, as in the previous figure: and in the lower Plane, its consideration is crucial for the true understanding of the steps, for if one is to strike, one must walk by one of its sides, or Perpendicular, that is considered in it, as will be seen in our universal demonstration of the Circle.

29. A Scalene Triangle is contained beneath all three unequal sides, like P.T. which is greater than T.R. and this is less than R.P. and is manifested in number 31.

Scalene Triangle

 

In Fencing, we use it, both in the lower Plane and in the upper one, for when we make the rigorous assault from inside, through a block, we consider the longest line to be the one we imagine coming from the tip of the right foot, converging with the opponent’s tangent; and the shorter one, the one that comes from the right heel, converging on the shortest path with the same tangent, and this tangent is the third side.

In the upper Plane, we consider in this assault the longest line to be the one imagined from the tip of the Sword, to the shoulder to the received line, or hilt; and the other line, which closes the triangle, is the Sword.

30. A Right Triangle is the one that has a right angle, as manifested in number 32. with the letter B. and the line that is opposite C.D. where its extremes converge, causing acute angles: is called Hypotenuse, being opposed to the right angle B. for whose discovery Pythagoras offered the sacrifice of a hundred cows to the Goddess Minerva.

Right Triangle

 

En la Deſtreza ſe forma eſte Triuangulo en muchos propoſiciones de la Eſpada, y Daga, quando ſe combate deſde el extremo propinquo, y con la Eſpada ſola ſe vè quando el contrario encoge, y baxa el brazo al Angulo agudo, y la punta de la Eſpada ſube al obtuſo, y el Dieſtro aplicando ſu eſpada con la graduiacion neceſſaria, ſea por de dentro, ò por de fuera, encamina herida de eſtocada, ſirviendo ſu eſpada de linea Ipotenuſa.

31. An oblique triangle, or obtuse-angled triangle, is one that has an obtuse angle; this is shown by the letter A. in number 33. Its application in Fencing is detailed in the preceding sections.

Oblique Triangle

 

32. An acute triangle, or acute-angled triangle, is one that has all three angles acute, as is shown by the letters M.C.P. in number 34.

Acute Triangle

 

Its application in Fencing is also covered in the preceding triangles, through the knowledge of the lines that compose them.

33. Among the quadrilateral figures, the square is the one that has all four sides and all four angles equal, as is demonstrated with the letters P.B.C.D.

Definition of a Square

 

If a straight line is drawn from one of its angles to the opposite angle, it is called a Diagonal, and this line will divide the square into two right triangles of equal surfaces, as shown by the line drawn from C. to B., all in number 35.

In Fencing, we consider the Square in the chest of each of the combatants; and also the Diagonal line that divides it from one angle to another; as well as the Quadrangle, or Parallelogram, which we consider on the face, where all the Diagonal wounds of the upper plane are executed.

34. A parallelogram is a flat figure, contained by four lines, of which the opposite ones are parallel, its species are the Square (already mentioned), the Rectangle, the Rhombus, and the Rhomboid.

Of the Parallelogram

 

A rectangular parallelogram is one that has all four angles equal, and only the two opposite and equal sides, like V.K. and C.D. in number 36.

Of the Rectangular Parallelogram

 

In Fencing, we consider it in the lower plane, and it will be seen in our universal demonstration of the circle, and also in the face of each of the combatants.

35. A Rhombus is an equilateral figure but not a right-angled one, composed of four equal sides, like the square: they differ in that their angles are unequal, and if two Diagonal lines are drawn from one angle to another, they will not be equal, and its sides are equidistant and of opposite contradiction, because the angles A.B. are obtuse, and C.D. are acute, as verified in number 37.

Definition of Rhombus

 

In Fencing, this figure serves for some propositions of the French doctrine, since when they affirm, they bend the knees to balance the body equally; and in this manner, it is seen perfectly if both heels are joined, as it is often executed in the progression of the battle.

36. A Rhomboid is a figure that has its sides, and angles, equal to the opposite ones, but it is neither equilateral nor rectangular; it is similar to the Rhombus, except that the opposite sides are longer, like A.B. is longer than C.D. and to the line designated by the O.O. dividing it from one angle to another, we call it Diagonal; and to the line that divides it into two Rhomboids, as indicated by the letters M. and M. we call it Diametrical, number 38.

Of the Rhomboid

 

And in Fencing, when the two combatants affirm themselves in a part of both postures (square, and profile) and the Swords are directed to the left shoulders, or collaterals of the same side, this figure is observed.

37. The remaining four-sided figures, which are not the aforementioned, are called Trapeziums; of this species, some are more irregular than others, the most regular one has two equal sides, like S.V. and the other two opposite sides parallel, like P. and N. in the figure of number 39.

Definition of Trapezium

 

In Fencing, when the combatants affirm themselves in square, and the tips of the Swords are pointing, one to the Diametrical of the chest, and the other to the left Collateral.

38. An Irregular Trapezium is the figure demonstrated by the letter Q. in the figure of number 40.

Irregular Trapezium

 

And in Fencing, it is useful in the doctrine of Beautiful Spanish; for when we affirm ourselves in it, the body slightly collapses, bending the knee in such a way that the thigh forms one side, and the leg forms another; the third side will be the distance that should exist from the left foot, which sustains the body, to the right one; and the fourth side will be the right leg and thigh, which will be without forming an Angle: this figure is also considered in other cases, which will be referred to when we discuss this doctrine in the third Book, which deals with all the strategies.

39. There are other figures with many sides, each having its particular names: like the one with five sides, which is called a Pentagon, the one with six sides Hexagon, the one with seven sides Heptagon, the one with eight sides Octagon, and so forth, infinitely.

Figures with Many Sides

 

Of these figures, some are called regular, and others irregular; the regular ones are those that have equal sides and angles; and the irregular ones are those that have unequal sides and angles.

The lines that contain these figures are called sides, those that divide them in the middle are called Diametric; and those that pass through the opposite Angles are called Diagonals.

Of these figures with many sides, we only use the Pentagon in Fencing, both the regular and the irregular, in this manner.

For the regular Pentagon, when affirming ourselves with the body in the French posture, equally on both feet, one heel will be distant from the other the same amount as the length of the thigh or leg; because from the birth that the thigh makes in the fork to the knee or bend, we consider one side; it is indicated by the letter A. the second side, equal to this, we consider from the knee, down to the ground; it is indicated by the B. the third is the other thigh, indicated by C. and the fourth the other leg D. the fifth, and last side, is the imagined one from one heel to the other; it is indicated by the E. figure, number 41. And for the irregular Pentagon, when the interval from one heel to another, is of greater, or lesser length, than the sizes referred to.

40. When dealing with any angle in a triangle, the lines that comprehend it are called sides, as demonstrated by the two C’s. And the line that is opposite to the angle A. is called the base, like the letter D.F. And the line that is drawn from the angle A. perpendicular to the base, is called the Perpendicular; and the parts of the base are segments, the greater D. and the lesser F. num. 42.

Of the Sides in the Triangle

 

Following the understanding of straight, circular, and mixed lines, and of right, obtuse, and acute angles, and of the flat Surface, which we have divided into different figures, both of three, four, five, six, and more sides; we now move on to the understanding of the curved Surface, which is divided into spherical, and mixed.

41. Spherical Surface, according to Euclid Defin. 12. of book 11. of his Elements, is formed by the revolution of half the circumference over its diameter: he does not say it in express words, but it is inferred from the definition he gives of the sphere, in this form.

Of the Spherical Surface

 

A sphere is a solid figure, contained by a single surface, to which, from a point that is inside, all lines drawn to the circumference are equal to each other; and the description, or formation of the sphere, is made with the revolution of a semicircle, over its fixed diameter, until it returns to the place where it began.

He does not specifically declare that the surface is caused by the movement of the circular line; but as said it is inferred, because the line with its movement causes surface; and he says, that the sphere, as a body, is contained by a surface, which cannot be other than the one described by the line of the semicircle C. and C. that moves over its diameter A.B. num. 43.

42. Mixed surface is the one caused by a straight line, moved circularly, or by the circular line, moved straight; as seen in the surfaces of the Cylinder, and the Cone, or conical Pyramid, and it is inferred from definitions 16. and 18. of Book 11 of Euclid, who says.

Mixed

 

The Cone is a solid figure, formed by the revolution of one side of a triangle, around another that remains still, like the triangle A.B.C. where the side A.B. moves around A.C. and causes the conical surface, and the whole triangle, being a surface, causes the body contained in the conical surface, figure number 44.

The same is seen in the following figure, which is called Cylindrical, which is caused by the revolution of the side A.C. in the parallelogram A.B.C.D. around B.D. this side causing the Cylindrical surface, in which the body of the Cylinder is contained; where it is seen, that this surface is called Mixed, as it is composed of two movements, or two different types of lines, one is circular, and the other straight, being formed by the revolution that the straight line makes around the other side.

It is also caused by the movement of the circle A.G.E. if it moved straightly from top to bottom, which can be more easily considered, if some circle moved straightly through some soft mud, in which it would have caused a Cylindrical surface, which they call Mixed, figure num 45.

There are other infinite differences in mixed surfaces, but these two are the most necessary in Fencing, as will be seen in their place.

43. Solid (according to Euclid, definition 1. of Book 11 of his Elements) is what has length, width, and depth, and its limits are surfaces.

Definition of Solid Bodies

 

In the same way that the line is divided into straight, circular, and mixed, and the surface into flat, spherical, and mixed; also, the bodies are divided into three differences: namely, those that are comprised of flat surfaces, such as the five bodies called Regular, and other infinite ones found in nature, those that are understood under mixed surfaces, of which there are many; but among all, in Fencing, we need to consider three of them, which are the Sphere, the Cylinder, and the round Pyramid, which although demonstrated, we will declare again, in this manner.

44. A sphere is a solid figure, contained by a single surface, from which, from a point within it, all the lines drawn will be equal to each other, as shown in figure number 46.

Definition of the Sphere

 

The description, or formation of the sphere, is made by the revolution of the semicircle, keeping its diameter firm and immobile, until it returns to the place where it began, as already explained.

45. A cylinder is a solid figure, formed by the revolution of a parallelogram around one of its sides, which remains still, until it returns to the place where it started: its axis, or axle, will be the side that was immobile, or the base of the parallelograms, as in this figure number 47.

Definition of the Cylinder

 

The parallelogram A.D., moving around B.D., caused the cylinder A.E. Its axis is the line B.D., its bases are C.H.E. and A.G.F., which were caused by the revolutions of the lines A.B.C.D. around the points B.D.

46. The cone is a solid figure, contained by two surfaces, one flat and the other mixed; it is formed by the revolution of triangle A.B.C. around or along the side A.C., which remains immobile, until it returns to the same place where it began. The side that remains immobile is called the axis, and the base is the circle that describes the base of the triangle, number 48.

Definition of the Cylinder

 

Apollonius of Perga provides another description of this Pyramid, saying: If from a point a straight line is drawn to the circumference of a circle, which is not in the same plane as the point, and the point remains fixed, the line moves along the circumference of the circle, until it returns to the same place where it started, or began to move: the surface described by the straight line is called a conical surface; the vertex, the point that does not move; the axis, the line drawn from the vertex to the center of the circle; and the Cone, what we call Pyramid, is what is contained by the conical surface, and the circle, and the circle serves as its base.

Another Description of the same Pyramid

 

For example, let point A. be in a different plane than circle B.C.D., draw a straight line from A. to B., a point on the circumference of the circle, and with point A. fixed, move the line A.B., or the extremity B., along the circumference of the circle B.C.D, it will describe a conical surface, its vertex will be A., its axis A.E., its base the circle B.C.D., and everything contained between the circle and the surface will be the Cone, or conical Pyramid, as shown in figure number 49.

These three bodies are of great consideration in Fencing, as will be mentioned in their place: the first, which is spherical, is not only used to consider the movements made within the jurisdiction of a sphere, which is formed, or considered formed with the movement of the Sword; but it also serves to consider some horizontal, vertical, and oblique planes, along which the Sword must move, for the formation of strategies that resemble the circles considered in the celestial sphere.

El Cilindro nos ſervirà para repreſentarnos vn Caſtillo, en que conſideramos pueſto el Dieſtro, que tambine ſe formarà del movimiento de la Eſpada.

The Pyramid is also very necessary, because its consideration and its formation not only serve to defend the fencer, but also give him knowledge for the offense.

Lamina primero del Libro ſegundo

 

First Plate of the Second Book