the Place is by so much the stronger and consequently better because gains more Sideâ— VI. The Angle of the Bastion must never be greateâ— than 100 Degrees nor less than 60 for being bigger the Face cannot be defended as it ought to be and being less it is not able to resist the Injury of the Weather or the Efforts of the Mines and Cannon See Chap. 1. Sect. 4. of Book IV. VII The greatest Angles are best to fortify VIII The Angle of the Curtain ought never to be less than 90 Degrees nor greater than 110 because if it be larger 't is too much subject to the view of the Enemy See Chap. 1. Sect. 5. of Book IV. IX The great Demi-Gorges are to be preferred before the small ones as well because there is more space to retrench in as because one may make retiring Flanks which adds very much to the strength of the place X. Great Flanks are best XI The Face ought to be never less than the half of the Curtain if it be not in an Irregular Fortificationâ— XII The Faces of the Bastion ought to be defended by the small Shot of the opposite Flanks XIII The shortest Faces are best because they are not so subject to be attacked as when they come ouâ— a great way in the Country See Chap. â— of Book IV. XIV The Curtain ought never to be shorter than 60 Fathoms which is 360 foot English nor longer than 100 if it be not in an Irregular Fortification XV. The Line of Defence must not be of greater length than 120 or 125 fathoms because a Musquet can carry no farther to do execution Holdman goes contrary to this Axiom when he says that it may be 150 fathoms and likewise George Pascha who believes it may be 136 fathoms long XVI The Taluâ— or Level ought by no means to be forced or streightened but oâ—ght to have sloap enough that the Ground or Earth may settle of itself XVII Large and deep Trenches are to be preferred before those that are narrow and hollow or large and less deep because the Enemy will find more difficulty to get over the first sort See Chap. 10. of Book I. XVIII Dry Trenches are to be esteemed before those that are full of Water especially in great Places where Sallies Retreats and Succors are necessary XIX Trenches full of Water that cannot easily be drained ought to be preferred before those that are dry in small Fortresses where Sallies Retreats and Succors are not so necessary XX. The Outworks ought always to be lower than the Body of the Place and those that are at the greatest distance ought to be the lowest CHAP. II. Of the Situation of Places AS it is very rarely permitted to make choice of that space of Ground which is to be fortified but on the contrary the Place is almost always determined whether we design to repair an old Fortification or surround any Town with Bastions and other kind of Works or whether we are to make ourselves Masters of the Passage of a River of any strait Place or an Eminence that is of advantage to command the flat Country or an Island in a River or of one or more jettings out of Land into the Sea for the making a Port and lastly for several other Uses the recital whereof would be too tedious It is necessary upon these Accounts to understand what kind of Situations are best for the Erecting a strong Hold and to know the Opinions of others concerning this Matter I. What are the Advantages of a Fortress situated upon a Mountain 1. This Fortification is not easily Ruined by Mines 2. The Enemy will be at a great deal of difficulty to bring their Machines to batter down this Fortification 3. Those of the place may discover the Enemy at a great distance and so hinder them from making their Approaches nearer 4. The Horse or Batteries of the Enemy which are planted either on plain or rising Ground can no ways do any damage to this Fortification it being always lower 5. Upon an Eminence the Air is always more healthy than in Vallies or lower Places 6. The Enemy will but very rarely be able to take such a Place by Assault What are the Disadvantages of a Fortress built upon a Rock 1. They commonly want Water in such a place 2. It is difficult to bring thither Materials Provisions â—nd other Ammunition 3. These Fortifications are for the most part not very durable having only a sandy or gravelly Earth for Foundation 4. Places so situated are not to be succoured but with great difficulty 5â— Such a Place cannot well be defended becauâ—e what is done by the Cannon from top to bottom is but of little consequence 6. Sallies are there very dangerous especially if they be at any distance from the Counterscarps 7. These Fortifications are almost always Irregular Advertisement It is to be observed that these kind of Situations are good for Cittadels Castles and other small Forts in order to command the Country thereabouts II. The Advantages of a Marshy or Fenny Situation 1. The Enemy cannot come near it without danger of being lost 2. This Fortification is not easily blown up 3. These Places may be fortified for little Charge 4. They have there no need of a great Garison The Disadvantages of a Marshy Situation 1. It is almost impossible to relieve it 2. It must be strengthened with Piles driven in 3. Sallies thence are commonly unsuccessful 4. The Air is there always unhealthy which is the occasion of frequent Distempers because the Water there is always corrupted 5. These Places may be attacked without any great loss of Men provided they stay till the Frosts III. The Advantages of a Place encompassed round with Water 1. It cannot be undermined 2. There is no occasion for any great Worksâ— 3. The Enemy cannot always discharge their Cannon with any certainty because the Water abates much of their force 4. The Besieged may very easily set fire to the Enemies Shiâ—ping 5. â—he Naval Army is too much exposed to the â—iew of the Artillery of the Place The Disadvantages of a Place surrounded with Water 1. The Enâ—my may â—asily stop their Provision and hinder their Succors 2. Boats alone are sufficient to attack such a place and so there is no occasion for Horse 3. These Places are more subject to Diseases than otheâ—s Advertisement We may affirm that these Places that are encompassed all round with Water which cannot be quite drained or at least with great difficulty are the best notwithstanding because they are as it were fortified by Nature IV. The Advantages of Places situated upon an open Rising Ground 1. There is great Plenty of good Earth 2. They are never there in want of Water 3. Almost all these Places are commonly Regular 4. They have there Earth enough to make Retrenchments in case the Enemy make their Attacks with great fury 5. The Enemy had need to have two or three Armies if they would
to throw into Moats and Breaches to stop the hasty coming on of the Enemy Covert Way is a Walk round about the Moat towards the Country having a Foot-pace and the Glacis for a Parapet The Chemin de Ronde is a Walk between the Rampart and the Wall The Shirt or Chemise is the Soâ—â—dity of the Wall from the Talus to the Stone Row Chevaâ—x or Freisland Horses so call'd because first made use of at Groningen a City of Freisland are great pieces of Wood with six Sides driven through Piles or Stakes of Wood armed with Iron to hinder the Horse and Foot from going forward Circumvallation is a Moat bordered with a Parapet which slanks it self from distance to distance sunk about the Besiegers Camp as well to hinder the Relief of the Besieged as to stop Deserters Clayes are Twigs interwoven together having the Figure of a long Square they are plac'd upon an Allodgment and cover'd with Earth and sometimes they are laid upon marshy Ground to consolidate it Coffâ—r is a hollow'd depth from 6 to 7 foot and broad from 16 to 18 all athwart a dry Moat Upon the upper part of this they place a Parapet and a Cross pieces of Wood cover'd with Clayes loaden with Earth Commandment is a height of 9 foot which one place has above another Complement of the Curtin is the remainder of the Curtin after you have taken away its Flank to the Angle of the Gorge Complement of the Line of Defence is the remainder of the Line of Defence after you have taken away the Angle of the Flank Counter-Approaches are Works which the Besieged make to hinder the Approaches of the Enemy Counterscarp is properly the declining of the Moat on that side next the Country although by this term is understood the Covert-way with its Parapet Counter-Forts are certain Pillars and Parts of the Walls distant from 15 to 20 foot one from another which advance themselves as much as may be in the Ground and joyn themselves to the height of the Cordon by Vaults to sustain the Chemin de Rondes and part of the Rampart to fortifie the Wall and strengthen the Ground Counter-Gards are Triangular Pieces in form of a large Parapet which raise themselves above the Moat before the Faces and the Point of the Bastion to preserve them Countermine is a Subterranâ—al Way which the Besieged makes in search of the Enemies Mine to take away the Powder and frustrate the effect of it though fir'd by the Assailant Countervallation is a Moat guarded with a Parapet which the Besiegers make to secure themselves from the Sallies of the Garison Corbeills are a sort of Gabions fill'd with Earth plac'd upon the Parapet to fire upon the Enemy without being seen by them Cordon is a row of Stones made round which is plac'd where the Wall ends and the Parapet begins and it runs round about the place Coridor is the Covert way above the Counterscarp round about the place between the Moat and the Palisadoes Cornes or Horns are Outworks which advance toward the â—â—eld and carry in the fore part two half Bastions in the form of Horns which they present to the Enemy Crowning is a Work drawn beyond the Horns to keep the Enemy at a distance Curtin is the longest streight Line that runs about the Rampart drawn from one Flank to the other and border'd with a good Parapet 5 foot high behind which the Soldiers place themselves to fire upon the Covert way and into the Moat Cuâ—ette a little Moat about 4 fathom broad which is usually sunk in the middle of a great dry Moat till you meet with Water It is good to prevent the Besiegers Mining D. Defenses are all sorts of Works that flank one another and which the Enemy desires to ruin before he strive to pass the Moat Deâ—ilé is a streight narrow passage through which there is no marching but in file Dehors are all sorts of separate Outworks as Ravelins Half-Moons Hornworks Crownworks Counter-guards Tenailles c. the better to secure the main Place Demi-distance of Polygons is the distance between the Exteriour Polygons and the Flanks Demi-gorge is a Line drawn from the Flank to the Angle of the Polygon Demi-lune is a small flank'd Bastion plac'd before the Point of a Bastion when it is too weak sometimes this Work is plac'd before the Curtin when the Moat is a little wider than it ought to beâ— Dâ—scent into the Moat is a deep digging into the Earth of the Covert way in form of a Trench of which the upper part is cover'd against Artificial Fires to secure the descent into the Moat Distance of Polygons is the Line compos'd from the Flank and its Prolongation to the Exterior Polygon Donjon is a Place of Retreat to Capitulate with more advantage in case of necessity E. Embrasure the Hole through which the Great Guns are discharged Embuscade the Place where the Souldiers hide themselves to surprise the Enemy Enceinte the Circumference of a Place sometimes lin'd and compos'd of Bastions and Curtins sometimes not Esplanade is the place void of Houses between the Cittadel and the Town F. Face is the most advanced part of the Bastion toward the Field and is the first Attack'd Fascins are Bavins of small Wood two Foot broad and four long bound about at the ends and middle thrown into Moats where there is much Water to facilitate the passage over to the Wall Fals Braye is a small Rampart four Fathom wide border'd with a Parapet and a Banquet running round about the Body of the Place It is made use of to Fire upon the Enemy when he is already so far advanc'd that you cannot force him back from off the Parapet of the Body of the Place or else to receive the Ruins which the Cannon make in the Body of the Place Flank is the part which joyns the Curtin to the Face of the Bastion from which the Face of the next Bastion requires its Defence Flank Covert is that the exteriour part of which advances to secure the innermost which advanced part if it be rounded is called an Orillon Flank Fichant that which plays and fixes its Bullets in a direct Line in the Face of the adjoyning Bastion Flank Razant is that from the Conjunction of which with the Curtin the shot razes the Face of the next Bastion which happens when the Face cannot be discovered but from the Flank alone To Flank a Place is to play upon a place in such a manner that there shall be no part of it but what is Defended and from which you may play upon the Enemy both in Front and Rear and so oblige him to retire Forts of the Field or Fortins are all Fortresses whose Flank'd Angles are distant one from another 120 Fathom They are only for a time to guard some Passage or dangerous Place or else they are used in Circumvallation Fougade is a small Mine made under the Ground which the Enemy would blow
intercept the Provision and Ammunition coming to those of the Place from all Parts The Disadvantages of Places erected upon Rising Ground 1. The good Soil that there is about such a Place serves only for the Enemy to make Retrenchmen◠〈◊〉 Batteries Approaches Redoubts and other Works from whence they may do great Damage to the Besieged 2. The Enemy may form their Camp as those of the Place did their Fortification that is to say they may give it a Regular Figure and encompass it with a good Trench and a good Rampart 3. The Ground is very good to make Mines under such a place 4. The Enemy may seize all the Fruits growing about these places Advertisement These Places however are best because those of the place will take double the Advantage that the Enemy can have V. The side of a Mountain is a very ill place to fortify and it must be avoided as much as may be because the top of the Mountain almost always commands the Place within VI. The Valley is is no good place to fortify because the Enemy may discover them from the top of the Mountain VII The Advantages of Places situated on the Sides of any Great River 1. You may bring thither by Water whatsoever is necessary for Building and for the Soldiers 2. You may fortify the Circumference after the Regular manner or at least very near it The side towards the Water is fortified with small Charge 3. It may be easily Relieved 4. Earth is there very plentiful for repairing thâ— Works and for making Retrenchments 5. You may there make Sluces to put all the Country thereabouts under Water 6. They never want there any Water 7. The Enemy must have a great many Troops to â—ay Siege to such a Place by reason of the distance of the Qâ—arters 8. If it be attacked only by Land nothing hinders but that the Besieged may pass the River at pleasure and receive Succors by Boats 9. If it be attacked both by Land and by Water there must be two great Armies which will be very Chargeable The Disadvantages of Places situated on the Sides of a Great River 1. The River serves the Enemy for transporting whatsoever is necessary for a Siege 2. The Enemy may cast up great heaps of Earth to Command the Place 3. The Enemy may easily shelter themselves from the Firing of the Besieged having great plenty of Earth Advertisement 'T is not to be denied but that these Places are to be preferred before any of those that we have now mentioned in case they are Masters of the Pass by which the Provision and Ammunition is to come in CHAP. III. Of the Quality of the Earth WHen you have once made choice of a Place for the erecting a Fortress before you Engage yourself in so expensive an undertaking you must examine the Quality of the Earth and consider whether it be Good or Bad For there are very Advantageous Situations the Earth whereof is good for nothing and on the contrary there are Ill Situations that have a very good Soil but they lie subject to be Commanded after such a rate that it would be great folly to settle there As may be evident by the following Observations Sect. I. MOuntains commonly have a stony Ground which is the worst of all as well because it will not stick together as because the Parapers made thereof are good for nothing But if you are compelled to fortify in such a place you must make choice of the best Veins of Earth to make the Parapet and cause it to be brought from elsewhere 'T is true this sort of Earth is of some advantage in that the Besiegers will find it difficult to cover themselves in their Approaches for want of good Earth Sect. II. THE Gravelly or Sandy Earth is likewise very bad by reason that it wants a binding Quality being always apt to tumble down when you are forced to make use of this you must mix some good Earth therewith or some old Dung and the Ramparts must be well lined with Stonâ—s or Bricks and the Parapets with Turfs Sect. III. THE Marshy Ground is better than the two former sorts although generally 't is not very good because when it comes to dry being raised into Ramparts and Parapets it is subject to fall to pieces besides 't is difficult to find Earth enough about a Marshy place for raising Ramparts Parapets and Glacis of a reasonable height and moreover the Foundation of these Works must be always strengthened with Piles But if there bâ— a necessity of raising Fortifications in these places it must be during the Heats that so the Earth may have the greater Consistence Sect. IV. THE best kind of Earth for Fortifying is that which they call Fat or Fertile Ground because 't is pliable and you are not obliged to strengthen the Foundation with Piles nor to line the Ramparts unless you will CHAP. IV. Of Provision and other Necessaries SEing a Place cannot be able to endure a long Siege if it has not wherewithal to make resistance therefore there must be Provision made of whatsoever is necessary for a Soldier under which Head is to be understood Money to pay the Troops Meal Corn Hay Wine Beer Brandy Butter Salt Wood Powder Lead Match Bullets Cannon or Great Guns Musquets Pikes Sulphur Pitch Brimstone Palisadoes Chevaux de Frise Hand-Mills Horse-Mills and Wind-Mills that so if the Enemy should cut off the Water they might not be without something to Grind their Corn. A good Commander will take care of all this An able Physician Chirurgeon and Apothecary are there likewise very necessary To these there might be added some other Things requisite in order to keep the Soldiers in good heart A NEW TREATISE OF Fortification BOOK III. CHAP. I. Sect. 1. How to inscribe any Polygon within a Circle givâ—nâ— THIS Problem is commonly treated of in Geometry Nevertheless because it is impossible to work on a Regular Fortification on Paper without knowing before-hand how to inscribe Regular Figures in a Circle given or taken at pleasure we shall at present discourse something thereof 1. Divide the Diameter of your Circle given A. B. into as many equal parts as you would give sides to your Figure For example into Five 2. Draw the Diameter A. B. and make with this distance of points A. B. 〈◊〉 Aâ—â—â—es to intersect in C. 3. Draw from the Point C. through the second Part which is mark'd by the Point E. of the said Diameter a Riâ—ht Liâ—â— tâ—ll it toâ—ch the â—ircumfeâ—ence 〈◊〉 beâ—oâ—â— the Diâ—meâ—â—r in â— 4. This distance from the Intersection to the first â—â—int A. of the Diameter will be always one side of the Polygon demanded See the Plate B. Fig. 2. Seâ—t â— How to make a Scale AS every thing is to be done by a Scale you must know likewise the manâ—er how it is made which is as follows 1. Divide a Line into 10 equal parts and one of these to shew the
the Place of an equal bigness to the Line DE that is to say of five Fathoms as KI to the end that you may have the Brisure where you may place the piece of Cannon that points towards the Half Moon cannot be batter'd from the Field because it is as it were covered by the Ravelin Lastly To make the Rounding of the Flank retir'd take the Distance KE between the Points of the Compass and make Sections toward the Moat in L from whence afterwards draw the Arch from K to F. It cannot be said but that these Orillons are very good for these Roundings give less advantage to the Enemies Cannon and enlarge the room as well for placing the Cannon as for the Musketeers If you object That the Distance from that part where the Enemy may pass the Moat is too great I answer That the principal Defence of the Small Shot to hinder the Passage of the Moat consists in the Tenâ—ille where you may set a Body of Musketeers to fire continually Upon this Method Monsieur de Clermont observes That the Orillon of the Square would be too little if you allow it no more than the Third Part of the Flank as to the Polygons and therefore he requires Two Fifth Parts of the same Flank for the Orillon See the Plate P. Fig. XXII at the end of the Third Book CHAP. V. Of the Curtain IN regard that the Curtain ought to cover the greatest part of a Work it is requisite that it should be of a reasonable Length that is to say that it should never be shorter than Sixty Fathoms and never longer than an Hundred Mâ—rshâ—user allows it 72 Fathoms and Freittag as much Goldman would have the Length to be of 96 Fathoms Anthony de Ville 100. Tieu makes it 74 Fathoms in Length Himsel 84. Monsieur de Clermont allows it Three Fifth Parts of a Polygon The Count de Pagan 60 Fathoms Monsieur de Vauban forms it according to the Plurality of the Bastions As you may see Lib. 3 c. 17. As to the Figure of the Curtains there are some Engineers who will have them â—o be as is mark'd at the Letter A of which the Construction is such See the Plate P. Fig. XXII at the end of the third Book 1. Divide the Line AB into â— equal parts as AD DM NC and CB and take â— for the Demi-Gorge as BC AD. 2. Divide the same Line AB into three equal parts and take one for the Capital as BE Aâ— 3. Where these three Parts are marked as at R and G bring down from the Points R G two Perpendiculars of which seâ— each have the third part of the Capital Line for its length as RH and GI and then joyn H and I together by a Right Line 4. Make upon the Points D and C the Angle of the Curtain of 100 degrees and allow to the â—lank the length of the Demi-Gorge â—â— DP and CQ This being done joyn EQ and DP together to have the Faces The defects of the Curtain are 1. That it is too short 2. That the â—ortification takes up too much room 3. That it renders the Bastion too Acute Others there are that form an Angle without side as that which is marked with the Letter B. The Construction of which is after this manner 1. Divide the Line AB into five equal parts as AC CD DE EF and FB 2. Divide the first Line AB into three equal parts and allow one for the Capital as AI and BK then join HI and BK together to gain the Faces 3. Divide the Curtain CF into two equal parts and upâ—n the middle marked with the Letter L erect a Perpendicular which has the half of the Face GK as LM 4. Draw from CF two streight Lines to the Point M and your Curtain will be made See the Plate P. Fig. XXIV â—â—hers make the Curtain of a Câ—rcular Figure withinâ—sâ—de like that which is marked C The Construction of which is as follows See the same Plate Fig. XXV Having observed what has been said touching the three first Points of the Preceding Curtain take the Extremities of the Curtain BC and make two Arches to cross or cuâ— one another underneath and from this Point of the Intersection draw an Arch from one end of the Curtain to the other Lastly There are others that form the Curtain of a Circular Figure without side like that which is mark'd D. The Construction of which is like to that which we have already describ'd only that here you make the Intersection above the Curtain in E From which Point you afterwards draw the Arch from one end of the Curtain to the other The Breast Curtains are those which are drawn streight out-right from one Flank to another See the same â—lank Pâ— at the end of the third Book Fig. XXVI CHAP. VI. Of the Parapet IN regard that this Work is raised to cover the Cannon and the Soldiers which defend the Place it must be allowed a reaâ—onable heighth and breadth Cellarius allows it six Feet in heighth with a Foot of sloping within sideâ— to the end the Soldiers may be able to stand the better when the Parapet is reared after that manner The heighth without side from the Cordâ—n ought not to be above four Feet because the â—loping which is made by those different Heights inward and outward gives the Soldier an easier view of the Covert-ways and the Moats that are before him As for the Thickness of the Parapet Monsieur Clermont allows it for the Basis the third part of the Basis of the Rampart The Count de Pagan makes it three Fathoms broad Of which opinion are several others as Goldman Frâ—ittag and Monsieur Vauban himself So that we may boldly say That the Thickness of the Parapet is good when it is not less than 18 Feet nor broader than 24. For being weaker the Parapet cannot long resist the force of the great Shot which would soon level it with the Earthâ— and being thicker it would hinder the Soldiers from the sight of the Moat and the Covert way If you would line the Parapet it must be allowed a little â—loaping that the Soldiers may have the better footing The best Lining of Parapets is with Turf As for the Earth or Mould which you are to make use of in erecting a Parapet it is very requisite to mix it with Withy Twigs or Brambles and to sow it with any Weeds that take a deep root to bind the Earth together so that the Cannon may not easily crumble it down Hay of Burgundy is also very good for this purpose in regard that there is no Plant that puts forth more or deeper Roots CHAP. VII Of the Banquets AT the foot of the Parapet upon the Plat-form are usually made two little Steps or small Banks of which the first is about two Feet broad Goldman makes it four Feet Frâ—ittag 3. the Count of Pagan 2. Monsieur Clermont the same and one Foot and
the short statuâ—â— Soldiers CHAP. XIII Of False Brayes HEre it is that some will ask me why the French admit no False Brayes in their Fortifications as being a second Defence and an admirable Work to dispute the Counterscarp with the Enemy and to hinder him from crossing the Moaâ— Moreover it is certain that small Shot does more Execution from a low than a high Place Besides that the small Shot placed in the False Bray doubles the Defence of it as that Work doubles the Defence of the Place But if you talk of the Defence Why do you then put the Counterscarp before the Faces knowing that those Parts defend nothing You will answer that this is to dispute the Passage of the Moat But consider that the Enemy having broken the Parapet of the Point may afterwards pierce with his great Gâ—ns the Walk that runs all along the Face Besides that the ruining of that Work is very advantageous to the 〈◊〉 who would willingly have wherewithal to fill the 〈◊〉 As for the part of the False Bray that is before the Curtain it is no longer good because it does not flank the Faces of the Bastions nor hinder the Passage of the Moat which is objected always for the principal Reason Nevertheless the remainder of that Work which is before the Flank will be good But know that this part is easily rendered unserviceable by the Ruine of the Rampart and the Parapet of the Flank which falling within side fills up its Platform And if the Rampart be lin'd the Splinters of it maim the Soldiers that guard that Flank of the False Braye To remedy which Defects the French now adays erect Tenailles in the Moat before the Curtain and before the Flanks separated from the Body of the Place by a little Moat to the end the fall of the Rampart of the Body of the Place may not kill or wound those that are in it being lined with Walls There is nothing of all that you talk of False Brays that can be attributed to these Tenailles besides that they cast not the half of what those other Works do CHAP. XIV Of Cavaleers CAvaleers are one of the best Defences of a Place because they most notably scowre the Field which obliges the Enemy to open his Treâ—ches at a great distance in regard these are as so many second Bastions which are opposed to the Enemy And moreover that they defend the Passage of the Moat command the Covertâ—way and above the Glacis 't is certain that being well disposed they may defend the Head of the Breach which the Enemy shall make in the Face of the Bastion wherein those Cavaleers are erected Now A Figure shewing all the angles in a Square A Draught Square of Vaubane For § 3 Book III Chap V. Fig VI. For § 2. Book III Chap V. Fig V. For § 4 Book III Chap V. Fig VII in regard that Opinions are different as well in respect of the place where â—hey are to be set as in regard of their Figure Let us see the Reasons both of the one and the other 1. There are some that would have the Cavalcers plac'd upon that part of the Curtainâ— which discovers the Face of the opposite Baâ—tion that is to say upon the Lines of the second Flank as Aâ— the Construction of which is such See the Plate Q Figure XXVII 1. Bring down a streight Line perpendicularly under the Flank and upon this Line put two third parts of the Demi-gorge as A B. 2. Divide the Line AB into two equal parts as AC CB and prolong perpendicularly the Point C till this Prolongation be equal to the Demi-gorge as C D. 3. Bring down also a Perpendicular from the Point D of the Length CB as DE and at length join BE togetheâ— by a streight Line 4. Having rais'd the Cavaleer to a just Height they give it a Parapet of thâ—ee Fathoms and two Banquets as is usual 1 But it may be objected against this Situation thâ—t the Cavaleer does not flank but very obliquelyâ— and by consequence that the Effects of it are of little consequence 2. That the Ruines which the Enemy's Cannon will make as being oppos'd to it in Front falling between the Curtain and the Cavaleer will hinder the Execution of the Small Shot of thâ— Second Flank II. 1 Others loâ—ge the Cavaleer in the middle of the Curtâ—in and give it a Triangular Figure alledging That in that partâ— one and the same Cavaleer may flank two Faces of the Bâ—stions To which it is answered That a Cavaleer cannot be erected after that manner but in Places which have more than half the Curtain for the secâ—nd Flank which would be very difficult unless it were in Ciâ—ies where the Angles of the Polygon are of a very large Oveâ—ture For to say we oâ—ght to make these second Flanks veâ—y large as well to aâ—gment the Firing from the Curtain as to gâ—in room foâ— placing of thâ— Cavaleer this is to make Bastions in a Place that serve for nothing because that by this means the Flanks are made so small that they seem to be only for Ornament 2. That the Enemy stands in no fear of the Firing from a Cavaleer dispos'd after that manner when once he is lodg'd upon the Counterscarps because it is too high and the Cannon cannot plunge low enough The Construction of this Cavaleer is such See the Plate Q. Fig. XXVII B. 1. From the Curtain bring down a perpendicular Lineâ— and put there above 14 Fathoms as AB 2. Take that Distance and draw from the Point B a Circle 3. Divide this Circle into Three equal parts beginning from the Point A as AC AD and CD which joyn together by right Lines and this shall be the Base of the Cavaleer 4. Draw on the Sides AC and AD the Base of the Parapet of 3 Fathoms But it is to be observ'd That these Cavaleers are not to be erected but from 9 to 10 Feet above the Platform of the Rampart unless there be very strong Reasons to raise it higher In the mean time 't is very true that this Cavaleer is not better than the preceding because the Angles of it are very acute for when the Angle A is carried away all the rest is worth nothing since neither Cannon nor Soldiers can subsist upâ—n the side AC and AD by reason of the Enemy's continual playing upon them III. Some raise the Cavaleers upon the Platform of the Bastion and dispose it in such a manner that the Faces and Flanks of the Cavaleer are parallel to the Faces and Flaâ—ks of the Bastion as C. The Advantages that proâ—â—â—d from this Disposition are that the Enemy being got uâ—â—n the opposite Counterscarp will be troubled to lodge his Cannon there by reason of the Cannon upon the Flank and upon the Câ—valeer which playing without ceasing will dismount the Enemy's Artillery hinders him from raising Shoulderings to secure himself Besides that the Breach of