The tracing of batteries is executed by the students of both arms, the other tasks by the artillery students alone.
I. DRAWING ORDNANCE (12 DAYS.)
The survey of ordnance consists in constructing accurate sketches of a gun, howitzer, and mortar, in measuring their dimensions, and in giving a description of each of the pieces drawn. It is on this occasion that the students are practiced in the management of instruments to insure precision, such as theétoile mobile, and the sliding compass, &c. One day is devoted to this work.
The tracing of ordnance consists in the execution of a drawing upon colombier paper, containing an exact and detailed representation of a gun, a howitzer, and a mortar, with their projectiles.
This work is performed with the help of the tables for the construction of ordnance. Eleven days are devoted to it.
Detailed Programme of the Drawing.
1. For each gun, howitzer, or mortar, a longitudinal in the direction of the axis, and at right angles to the axis of the trunnions, and a plan parallel to the axis of the bore and of the trunnions.
Besides this, for those cannon and howitzers which have dolphins, a transverse taken across the middle of the dolphins and the axis of the trunnions. For mortars, a transverse made by a plane passing in front of the dolphins, the whole on a scale of one-fifth.
2. Detail of the button (comprising the cascable and breeching loop for naval ordnance) on a scale of two-fifths.
3. Detail of the tracing of a dolphin, on the scale of two-fifths.
4. Tracing of the bush of a gun, on a scale of two-fifths, and tracing of a priming-pan at the real size.
5. For garrison ordnance, in cast-iron, detail of the widening of the base ring on a scale of two-fifths.
6. Tracing of a cannon-ball, of a howitzer-shell, and of a shell, on a scale of one-fifth.
Tracing of the lugs of a shell, ring and lug at the real size.
All the parts of the drawing must be colored in uniform tints in conformity to the table of conventional colors; the annexation of the figures of measurement is not required.
This work is preceded by three or four lectures intended to make the students familiar with the tracings which they have to execute, and the solution of the problems in geometry and descriptive geometry, to which the representation on paper of pieces of ordnance and their projectiles give rise.
II. DESIGN FOR ORDNANCE (24 DAYS.)
The design for ordnance has for its object the complete determination of the nature of a projectile, and of a piece of ordnance in accordance with certain special conditions, inquiring into the laws of the motion of the projectile, and into its principal destructive effects, and the settlement of practice-tables for thegun. The general case for treatment is that of a howitzer, which comprehends the gun and the mortar as particular cases.
The data usually adopted are,—
1. For the projectile, its weight and the quantity of powder which it is capable of containing.2. For the piece, the initial velocity of its projectile. This operation comprises calculations, a drawing, and a memoir.
1. For the projectile, its weight and the quantity of powder which it is capable of containing.
2. For the piece, the initial velocity of its projectile. This operation comprises calculations, a drawing, and a memoir.
The drawing, on colombier paper, which must be figured in all its parts, contains,—
1. The tracing of the profile of the piece, as it is determined by calculation, so as to satisfy the different conditions of resistance, on a scale of one-fifth.2. The complete tracing of the piece executed in conformity with the rules laid down for the tracing of ordnance on a scale of one-fifth.3. Tracing of the projectile on a scale of one-fifth.4. Tracing of the wooden bottom and of the fuse of the projectile, executed in the case of each of these objects in two figures—the one on a large scale (two-thirds, or even the size of nature,) representing the inquiry into their forms and dimensions, the other giving on a scale of one-fifth the results of this inquiry. To this is added, for the mountain howitzer, or any other howitzer for which it is admissible, a tracing of the mounted howitzer carriage.5. The representation in drawing of the laws of the motion of the projectile, the trajectory, inclinations, remaining velocities, durations of the passage.In addition, the scale of the elevations and that of the angles of fire, for an object of aim placed at different distances.6. An inscription showing all the essential elements by which the projectile and the piece are distinguished.
1. The tracing of the profile of the piece, as it is determined by calculation, so as to satisfy the different conditions of resistance, on a scale of one-fifth.
2. The complete tracing of the piece executed in conformity with the rules laid down for the tracing of ordnance on a scale of one-fifth.
3. Tracing of the projectile on a scale of one-fifth.
4. Tracing of the wooden bottom and of the fuse of the projectile, executed in the case of each of these objects in two figures—the one on a large scale (two-thirds, or even the size of nature,) representing the inquiry into their forms and dimensions, the other giving on a scale of one-fifth the results of this inquiry. To this is added, for the mountain howitzer, or any other howitzer for which it is admissible, a tracing of the mounted howitzer carriage.
5. The representation in drawing of the laws of the motion of the projectile, the trajectory, inclinations, remaining velocities, durations of the passage.
In addition, the scale of the elevations and that of the angles of fire, for an object of aim placed at different distances.
6. An inscription showing all the essential elements by which the projectile and the piece are distinguished.
The final tracings of the gun, the projectile, the bottom, and the fuse, must be colored in uniform tints conformably to the table of conventional colors.
As to the tracing of the profile founded upon the calculation, it should receive merely an edging of the color which represents the metal used.
INTRODUCTION.
Object of the work. Data of the Question.
A.PROJECTILE.
First Section.—Substance, Forms, and Dimensions.
1. Choice of the metal employed in the manufacture of this projectile.
2. Forms of the projectile.
3. Internal diameter.
4. External diameter.
5. Dimensions of the vent.
6. Diameters of the high and low gauges.
7. Densities of the projectile empty and filled with powder.
8. Weight of the cast-iron ball of the same calibre as the howitzer shell.
Second Section.—Minimum Bursting Charge.
9. Theoretical bursting charge for the hollow sphere.
10. Effect of the shock of the gases, and of their loss through the vent.
11. Résumé of the results arrived at in this chapter.
B.ORDNANCE.
First Section.—Metal, Calibre, and Length of Bore.
12. Choice of the metal of which the piece is to be formed.
13. Windage of the projectile and diameter of the bore.
14. Effect of the windage on the velocity of the projectile.
15. Length of the bore and charge of powder which satisfy the data of the programme.
16. Résumé of the results arrived at in this .
Second Section.—Thickness of Metal necessary in order that the Piece may resist the Expansion of the Gases.
17. Explanation of the method employed to resolve the question of the thicknesses of metal.
18. First propulsion of the projectile, mean density of the gases after this propulsion.
19. Second propulsion of the projectile, mean density of the gases after this propulsion.
20. Third, fourth, &c., propulsions of the projectile, mean density of the gases after each of them.
21. Density and position of the strata (of gas) at the moment of the maximum of mean density.
22. Density of the last stratum for the positions which come after that of the maximum of mean density.
23. Tensions which result from the densities found.
24. Corresponding thicknesses of metal.
25. Résumé of the results obtained.
Third Section.—Profile of the Piece.
26. Inclosing curve, resulting from the calculations of the second .
27. Modification rendered necessary by the form of the posterior part of the projectile.
28. Utility of the chamber and its dimensions.
29. Tracing of the chamber and of its junction with the bore.
30. Thickness of metal around the chamber.
31. Chase and reinforce.
32. Determination of the angle of sight.
33. Vent and base ring.
34. Minimum weight of the piece for the resistance of the carriage.
35. Approximate calculation of the weight given by the profile previously obtained. Modification of this profile, if there is any.
Fourth Section.—Trunnions, Breech, and Handles.
36. Dimensions of the trunnions and of the shoulders.
37. Tracing of the breech.
38. Base rings and other moldings.
39. Object and fixing of the preponderance of the breech.
40. Exact settlement of the position of the trunnions, definitive length of the reinforce.
41. Center of gravity of the piece; dimensions and position of the handles.
42. Means of executing the calculations indicated in the two preceding articles.
43. Table of the dimensions of the piece.
C.FIRE OF THE HOWITZER. EFFECTS OF THE PROJECTILE.
First Section.—Elements of the Charging of a Howitzer.
44. Tracing of the shot bottom.
45. Tracing of the fuse.
46. Diameter of the cartridge (or of the bag.)
47. Charge of powder for firing with ball.
Second Section.—Laws of the Motion of the Projectile. Establishment of Practice Tables.
48. Preliminary calculations.
49. Trajectory.
50. Curve of the inclinations.
51. Curve of the remaining velocities.
52. Curve of the durations of the passage.
53. Determination of the elevations for the fire at different distances.
54. Angle of fire, corresponding to the different distances of the object aimed at.
55. Angles of descent.
56. Résumé of the laws of the motion and of the practice tables.
Third Section.—Effects of the Projectile.
57. Depth of penetration in the media indicated by the programme.
58. Effects of explosion in earth.
59. Résumé of the results relating to the effects of the projectile.
Note.—The formulas cited in the memoir need not be accompanied by their demonstration, except in the case of the latter not having been already developed in the lessons of the artillery course. It will be sufficient to insert in this notice only the final result of the calculation relating to each formula, without entering into the details of such calculations.
The study of the design for ordnance is preceded by four lessons intended to make the students acquainted with all the details of its execution, and the substance of which is indicated in the programme of thememoir.
III. APPLICATION OF THE THEORIES OF THE ARTILLERY COURSE (6 DAYS.)
This study is intended to apply to the students those theories of the course which have not found their application in the design for ordnance. It comprises the solution by arithmetical calculations of certain questions on the effects of powder, the balistic pendulum, the effects of recoil, the science of projectiles, the draught of carriages, &c. The number of the questions may vary according to their nature and the time which their solution requires. The stating of the questions and the results of the calculations are inscribed on separate papers. This study is preceded by a lesson in which the students have recalled to them the formulas which they have to employ.
IV. DRAWING OF ARTILLERY MATERIAL (26 DAYS.)
The drawing of artillery material has for its object the representation by figured sketches of a gun-carriage, carriage, or other furniture of artillery material. The sketches, on paper put together in the form of a book, and headed by a special programme for the object to be drawn, consist of plans, s, or elevations of the object, executed on certain scales, and of detailed projections of the principal iron-work and joints. The whole fixed by the special programme in question.
All the simultaneous projections of any one part of the object drawn (fore part or hind part for carriages) must be completely figured; they are accompanied by explanatory inscriptions, with letters of reference to show the names of the pieces in wood or metal which they comprise.
Each collection of sketches must contain as well a notice in confirmation of the drawing, giving the complete description and the properties of the object to which it refers.
The students make two surveys of the same kind; eight days are allowed for each of these surveys, including the composition of the confirmatory notice.
The first survey is followed by the execution of an unfigured drawing, containing a complete representation of the object surveyed (elevation and plan,) obtained by the combination of the partial projections contained in the sketch. The drawing should be colored in the conventional uniform tints, and accompanied by an explanatory inscription, with letters of reference. Ten days are devoted to this work of composition.
V. TRACING OF BATTERIES (4 DAYS.)
This work consists in executing sketches showing, each in accordance with a separate programme, the complete plan of a battery and the essential data having reference to its construction and to its armament. The sketches, made by scale and completely figured, must comprise in the case of each battery to be represented—
1. The general plan of the battery, on the scale of 1/200.2. The s or elevations necessary for the understanding of this plan, including the detail of the powder magazines, lines of communication, &c., on the scale of 1/100.3. An inscription giving the object of the battery, its armament, its general arrangement (terre-plein, embrasures, revetment, communications,magazines, &c.,) the workmen, materials, and tools necessary for its construction, and finally the duration of the labor and its distribution by day and night.Four days are devoted to this work, which must be executed on a half sheet of colombier paper. The separate programmes relating to each of these batteries are shown on the study orders of the rooms.
1. The general plan of the battery, on the scale of 1/200.
2. The s or elevations necessary for the understanding of this plan, including the detail of the powder magazines, lines of communication, &c., on the scale of 1/100.
3. An inscription giving the object of the battery, its armament, its general arrangement (terre-plein, embrasures, revetment, communications,magazines, &c.,) the workmen, materials, and tools necessary for its construction, and finally the duration of the labor and its distribution by day and night.
Four days are devoted to this work, which must be executed on a half sheet of colombier paper. The separate programmes relating to each of these batteries are shown on the study orders of the rooms.
RECAPITULATIVE TABLE.—ARTILLERY STUDENTS.
NL Number of the Lectures.+A With application at 1h 50m.-A Without application at 3h.TC Total Credits.Q Number of the Questions.
NL Number of the Lectures.
+A With application at 1h 50m.
-A Without application at 3h.
TC Total Credits.
Q Number of the Questions.
S SketchesD Drawings.M Memoirs.Inv Inventories.ID In-door Attendance. 1½ hours.OD Out-door Attendance. 1½ hours.C Credits in round Numbers.
S Sketches
D Drawings.
M Memoirs.
Inv Inventories.
ID In-door Attendance. 1½ hours.
OD Out-door Attendance. 1½ hours.
C Credits in round Numbers.
* The time is doubled for the memoirs.† Ditto.
* The time is doubled for the memoirs.
† Ditto.
RECAPITULATION.
Lectures, 150Studies, 380530
RECAPITULATIVE TABLE.—ENGINEER STUDENTS.
NL Number of the Lectures.+A With application at 1h 50m.-A Without application at 3h.TC Total Credits.Q Number of the Questions.
NL Number of the Lectures.
+A With application at 1h 50m.
-A Without application at 3h.
TC Total Credits.
Q Number of the Questions.
RECAPITULATION
Lectures, 162Studies, 20182. Round number, 180.
The course is divided into six parts, and is made up of lectures and works of Application in the Halls of Study and on the ground.
The 1st part contains sundry historical notices on the Organization of Armies,
FIRST PART.—HISTORICAL NOTICES ON THE ORGANIZATION OF ARMIES.
The first lecture commences with explanations relating to the Greek and Roman armies; their order of battle, mode of marching; comparison of theRoman Legion with the Greek Phalanx, and of the Roman Legion under Marius and under the Emperors.
2. Military organization of the Franks under the Kings of the first race. Consequences of the feudal system, acting on the military organization. Feudal armies. Chivalry. Crusades, and war against England. Establishment of the first standing armies. Results dependent on the introduction of fire-arms. Progress made in the Art of War and in the organization of armies, from the sixteenth century to the present time.
3. Necessity for standing armies. Their proper character. Recruiting. Promotion. Degrees of rank. Station of the officers. Various positions of military men. On the composition of armies, Infantry, Cavalry, Artillery, Engineers.Corps d’Etat-Major.Composition of the army during the Revolution and during the Empire. Actual formation of a French army.
General Staff. Commissariat. (Intendance.)—Different services dependent on it.
Relations between the strength of each of the arms that make up an army. On other corps which are not classed among the principal arms.
4, 5, 6. Summary relating to the military organization of the principal Powers of Europe.
SECOND PART—ON TACTICS.
1. Definitions. Formations. Manœuvers; character of a good manœuver. Order of battle: first, of the Infantry; second, of Cavalry; third, of the Artillery; relating to Sharpshooters (tirailleurs.)
2. Brief summary of the principal movements in battalion drill to pass from line to the order in columns and reciprocally. Movements in column. Movements in battle. Dispositions to be made against Cavalry.
3. Of the principal movements in line. Order of battle. Line of battle. Formation of Infantry to advance against the enemy. Action of Cavalry. Principal formations. Charges of Artillery. Use of the Three Arms.
THIRD PART.—CASTRAMETATION.
1. General principles of castrametation. Situation. Construction and disposition of barracks. Camp of a Regiment of Infantry, of Cavalry, and of a Battery of Artillery.
2. Manner of tracing a camp on the ground. Huts; details relating to their construction. Tents. Bivouacs. Screens. Kitchens and camp ovens. Choice of the site of a camp; precautions to be taken for its security. Main guards. Advanced posts. Patrols and sentinels.
FOURTH PART.—FIELD FORTIFICATION.
1. Definition of fortification in general. Object and character of field fortification; its utility demonstrated by historical examples. Napoleon’s opinion. Essential principle of field fortification. Discussion on the ordinary profile of earthen entrenchments; on the dimensions to be given to the ditch in level ground.
2. Definitions relating to the trace; general principles. Redoubts.
3. On the elements of lines. Relation that should exist between the crest and the internal size of a closed work. Maximum and minimum of the sides of a square redoubt. Defects inherent to the trace of this kind of redoubt. Circular redoubts. Redoubtsen crémaillères. Star forts. Lines with bastions.
4. Revetments of various kinds; case in which the slope of the ditch should be reveted; choice to be made of the different kinds of revetments.
5. Exterior dispositions; accessories to the defense; abattis;trous de loups; palisades;chevaux de frise, &c. Precautions to be adopted with reference to such accessories.
6. Interior dispositions; armament of musketry, artillery, barbettes, and embrasures; their advantages and disadvantages; construction of.
7. Powder magazines of different kinds. Small earthen entrenchments; palisades, carpentry, or blockhouses; advantages and disadvantages of blockhouses. African blockhouse. Closing of field-works.
8. Artificial inundations; under what circumstances they can be considered as obstacles. Positions and dimensions of dikes. Details of their execution; what advantage can be drawn from an inundation having less than five feet depth of water.
9. What is understood by the defilading of a work. The defilading of fieldworks should, above all things, be made to depend on their trace and situation. Definitions: dangerous ground; dangerous points. Defilement of an isolated and closed work; in what case it is practicable. Use of traverses. A partial defilement may sometimes be sufficient.
10. Continuous lines. Broken lines. Traces of redan, tenailles, cromailleres. Bastioned lines. Comparison between continuous and broken lines. Principal objections to their use. Utility of each demonstrated under certain circumstances.
11. Lines in broken ground: their form should depend on the nature of the ground. On the manner of fortifying a table-land. Expedients for defilading portions of lines. On the manner of making use of the natural obstacles of the ground; forests, scarps, marshes, water-courses, &c. Method of fortifying a house, village, an open town. Defense of a bridge or road.
12.Têtes de pont. Utility of small earthen entrenchments in these cases to facilitate the passage of a retreating army. Traces of a largetête de pont. Principal circumstances relating to the use of lines in war. Lines of circumvallation and countervallation. Frontier lines. Retrenchments against a descent. Lines that an army should make in an enemy’s country, far from its base of operations. Entrenchment on the field of battle. Lines, mixed, proposed by General Rogniat.
13. Attack and defense of entrenchments, of a continuous line; of a line at intervals; of an isolated work, &c. Examples of the attack and defense of lines.
14. Instruction relating to the operations for profiling and defilading on the ground.
15. Instruction on the project of field fortification. Calculation of the dimensions of a ditch corresponding to the face of a work of a variable relief, and to be constructed in level or other ground. Details relating to traverses, small entrenchments; defensive caponnieres, and accessories to defense, &c.
16. On the construction of entrenchments. Practical operations and organization of workshops to obtain durable and solid work. Necessity, in most cases, for accelerating the construction of entrenchments. Vauban’s precepts. In what manner the work must proceed to obtain a useful result; and, in the event of plenty of hands, how to finish it promptly.
FIFTH PART.—ON MILITARY COMMUNICATIONS.
1. On roads. 1 and 2, Classification of roads. Section and trace of roads in level and mountain country. Details connected with the study of a project for a road. Particular conditions relating to military roads. Execution of paved and macadamized roads. Roads for passing difficult places by the use of fascines, logs, &c. Maintenance and destruction of roads.
2. On military bridges.
3. Observations on the currents and change of form in the bed of rivers. Fords. Transverse s, &c. Reconnaissances of rivers. Properties essential to military bridges. Relation between the buoyancy and the load in the case of floating supports. Anchorage. Construction of the abutments. Means of rendering bridges stable.
4. Construction of a bridge of boats in different ways. Bridges made of ordinary boats. Method of withdrawing a bridge of boats.
5. Raft bridge. Relation between the weight and the extrinsic load of a raft. Number of trunks of trees required for a raft bridge on a river of given dimensions. Weight of the trunk of a tree. Number and space between rafts. Construction of a raft and a bridge of rafts. Bridges of casks and trestles.
6. Rope bridges; their use. Calculations respecting the tension and diameters of ropes. Construction of a suspension bridge, and calculations relating to it.
7. Bridges on piles, carriages, gabions, &c.
8. Measures to be taken for the preservation of military bridges. Destruction of military bridges; also of masonry bridges. Reëstablishment of bridges.
9. Flying bridges. Ferry-boats, tubs, passage by fords, on the ice, by swimming.
10. Execution of the passage of rivers. Advancing and in retreating. Examples.
SIXTH PART.—STRATEGY.
1. Definition. Fundamental principles of all operations in war. In all cases there are—first, the base of operations; second, the point to be arrived at; third, the line of operations. Strategetical points and lines.
2. On marching. Preparatory and manœuvering marches. Advanced and rear guard. On provisions. System of magazines. Requisitions. Invasions. Battle. Examples.
3. On positions. War in a mountainous district. Retreats. Pursuit. Convoys. Partizans.
4. Winter quarters. Cantonments. War against irregular bands. Military reconnaissances.
5. Precis of the campaigns of the French armies.
6. Analysis of the principal campaigns of great captains.
These works consist of four Plates of Drawings, two Memoirs, and a Project, of Field Fortification. Of the four Plates of Drawings, two relate to Field Fortification, and two, accompanied by Memoirs, relate to Military Communications.
Plate 1—Elements of lines. Tracing, on the scale of 1/1000 of the interior crest (only) of a redan, lunette, redoubt, star fort, bastioned fort, according to particular data given to each Sous-Lieutenant. Construction on the scale of 1/200 of a complete profile for each of these works, supposed to be established on level ground. Complete calculation of the deblais and remblais for one of the preceding works, according to the instructions of the Professor.
Plate 2.—Details of a field-work. Trace on the scale of 1/200 of a portion of the work of which the deblais and remblais has been calculated. Graphic construction of a barbette and of a direct or oblique embrasure. Details of revetments in fascines, hurdles, turf. Pisé. Drawing of a blockhouse.
Plate 3.—Accompanied by a Memoir. Project of a portion of road on ground represented by certain lines, according to certain data.
Plate 4.—Accompanied by a Memoir. Military bridges.
1. Drawing of a portion of a bridge of boats, three openings being shown; the two first relating to the successive construction of the bridge, and the third, of the construction by portions.2. Project for establishing a raft bridge; the width of the river; the kind of troops to pass over the bridge; the length; mean diameter of the available trunks of trees and the length and scantling of the joints being given. The drawing to exhibit a plan of two openings of the bridge, and a transverse .3. Tressel bridge. To draw a longitudinal elevation and a transverse of a tressel bridge, being given the length of the top and of the feet of the tressels up and down the stream.4. Project for the repair of a broken arch; being given the opening of the head, the elevation of the roadway of the bridge above the level of the water; the depth of the water, the rapidity of the current, the kind of troops to pass over the bridge, and the available time and the resources as regards men and materials which can be had recourse to.
1. Drawing of a portion of a bridge of boats, three openings being shown; the two first relating to the successive construction of the bridge, and the third, of the construction by portions.
2. Project for establishing a raft bridge; the width of the river; the kind of troops to pass over the bridge; the length; mean diameter of the available trunks of trees and the length and scantling of the joints being given. The drawing to exhibit a plan of two openings of the bridge, and a transverse .
3. Tressel bridge. To draw a longitudinal elevation and a transverse of a tressel bridge, being given the length of the top and of the feet of the tressels up and down the stream.
4. Project for the repair of a broken arch; being given the opening of the head, the elevation of the roadway of the bridge above the level of the water; the depth of the water, the rapidity of the current, the kind of troops to pass over the bridge, and the available time and the resources as regards men and materials which can be had recourse to.
Programme of the Project of Field Fortification.
This project is made by the Sub-Lieutenants, according to certain data given to each of them. It has for its object to cause them to study:—1st. The trace. 2d. The complete organization necessary for its defense. 3d. The details of construction of a field-work. In consequence, the work comprises three Plates of Drawings and a Memoir divided into three parts.
Programme of the Drawings.
Plate 1.—Plan of the whole. This plate has for its object the research of a trace and of a combination of suitable works for the fortification of a certain portion of ground under certain circumstances of war defined by particular data. Each Sub-Lieutenant receives a lithographed sheet representing the ground to be fortified, and he has to exhibit on this sheet the works he proposes, in tracing in plain lines the horizontal projections of the interior crests and superior limits of the ditch, and in dotted lines the stockades or palisades; to show in black figures at the angles of the works the relief of the interior crests; the sites of barbettes, embrasures, traverses, barriers, &c., being indicated by reference letters and explanatory notes, the lines in red showing the directions and objects of the line of fire.
Plate 2.—Organization of a work.
This plate has for its object the study of the details of the interior and exterior organization of a work of a certain form, in order to render it susceptible of making a good defense.
Each Sub-Lieutenant will draw a complete plan of such one of the works shown on Plate 1, as may be pointed out by the Professor. He will represent the ditches, parapets, embrasures, accessory defenses, small entrenchments, descents into the ditch, &c., according to the particular data furnished to him; the figures of the relief of the crests of all kinds, the deblais and remblais being marked at all the angles. The figures of the natural ground will be underlined. The same plate will contain figured profiles which have served for the determination of the complete projection of the work. Scale 1/250.
Plate 3.—Details of construction.
The object of this plate is to show the composition of workshops and the manner that should be adopted in the construction of field-works, according to circumstances, for the execution of the deblais and remblais.
Each Sub-Lieutenant will indicate the manner in which the work drawn on Plate 2 should be constructed:—1st. To render it durable and solid. 2d. To arrive rapidly at a useful result, even with limited resources of workmen and tools. 3d. To finish the work in the shortest possible time, by making use of all the necessary means. A plan will show the composition of the workshops under each of these hypotheses, and the successive advancement of the work will be represented by certain profiles supposed to be made at certain periods of the construction through the center of one of the faces of the work. In these profiles a firm trace, figured with altitudes, will show the limits of the deblais and remblais at the period represented by the profiles; and in addition by dotted lines, the final results proposed to be obtained. All these projects must be accompanied by a figured plan, showing the principal altitudes in meters. The remblais will be colored with gamboge, the undisturbed earth in bistre, and the deblais will be left white.
Programme of the Memoir.
Each Sub-Lieutenant will write at the head of his Memoir the text of the particular programme, to which he is obliged to conform in the preparation of his project, and he should add to the text of the Memoir all the sketches properly figured, which are necessary for the proper appreciation of the dispositions which are not sufficiently detailed on the Drawings.
The Memoir is divided into three parts, corresponding to the three Plates of Drawings.
FIRST PART.—CONSIDERATIONS RESPECTING THE WHOLE PROJECT.
1st. General principles, according to which it would be proper to trace the works indicated in the particular programme, such as lines at intervals, continuous lines, têtes de pont, &c.
2d. Description of the tracing in Plate 1. Reasons deduced from the form of the ground or the nature of the military operations that led to the adoption of the trace. Object of the works, and their connection with each other.
3d. Number, description, and position of the pieces of artillery composing the armament.
4th. Maximum and minimum of troops that could be employed in the defense of these works.
5th. Dispositions which should be adopted (relatively to the necessary preparations in materials and to the separation and movement of troops) for the attack and for the defense.
SECOND PART.—COMPLETE ORGANIZATION OF A WORK.
1st. Particular object of the work shown in Plate 2. Trace of the complete projections of the parapets, barbettes, ramps, embrasures, traverses, &c.
2d. Conditions that should be fulfilled by the ditch. Approximate calculation of dimensions which should be given to it, taking into account the increased means of providing for an excess or defect of the deblais.
3d. Discussion on the site and the part which might be expected from small entrenchments, accessory defenses, shutters, descents of ditches, &c.
4th. Site of powder magazines; capacity that should be given to them, suitable to the state of the munitions necessary for the armament of the work.
THIRD PART.—DETAILS OF CONSTRUCTIONS.
1st. Means of ascertaining the nature of the earth; considerations respecting relays for the transport of earth with the shovel.
2d. Description, number and disposition of the workmen in a shed for deblai and remblai, according to the nature of the ground and number of relays.
3d. Explanation of Plate 3. Organization of the sheds and conduct of the work where the duration and solidity of the work are the greatest essentials; where, on the other hand, rapidity of execution is the principal thing to be fulfilled.
4th. Which of the modes of construction exhibited in Plate 3 it would be desirable to employ for the proposed works, according to the circumstance specified in the particular programme. Calculation for this mode of construction, of the time and of the numbers of men and tools necessary for the execution of the deblais and remblais of the work given in the plate.
5th. Details of construction of the revetments, magazines, shutters, accessory defenses, artillery platforms, &c.
These works consist of an exercise in tracing out a camp, and an exercise on the profiling and defilement of field-works.
The exercise on tracing camps has no particular programme, but is preceded by a lecture given by the Professor.
Programme of Practical Exercises on the Defilement and Profiling of Field Works.
This exercise comprehends: 1st, work on the ground; 2d, a Memoir.
The work on the ground has for its object: 1st, the trace of the projections of the interior crest of a work, whose position and form are known; 2d, the determination of the relief of the interior crest; 3d, the profiling of the different parts, so that the relief of the different parts of the parapet, barbettes, traverses, &c., may all be fixed.
The Sub-Lieutenants for this kind of work are divided into groups of six or eight, employed together on the same work, each group being divided into two squads. The work may be a lunette or a redan of given dimensions, having aparapet of three meters thick, and a natural slope of one to one.
1st. The direction of the capital will be marked out in front by two numbered pickets.
2d. The tracing will be executed by means of poles or pickets placed at all the angles, and at the extremities of the gorge; the relief will be determined by the practical methods of defilement adverted to in the lecture which preceded the work.
3d. The relief obtained by the defilement will be marked on all the poles or pickets placed at the angles, and at the extremities of the sides of the work.
4th. On each face two vertical profiles will be executed, perpendicular to the horizontal projections of its interior crest. In order that these profiles shall not interfere with those placed at the angles, they must be established at several meters distant from the extremity of each face.
5th. The profiles of the angles will be deducted by simple prolongations, and the same for the profiles of the gorge. If the homologous crests of two contiguous faces do not meet each other, they should be reconciled by joining two points taken on each of them at half a meter from the inter of their projections.
6th. On the traverse, designed to secure the defenders from a reverse fire, two profiles are constructed, near to its extremities if its crest is a right line, but if it is bent, another profile must be set up at the junction.
7th. The data of all these profiles are, the relief of the interior crest at the point where it is encountered by the profile, the thickness of the parapet, the constant parts of every profile, and the natural slope of the ground; the portion of the slope of the traverses exposed to the view of the dominant heights should not be reveted, the others should be.
8th. At the points of inter of the profiles with the projections of the ridges of the works, as well as at the points used for adjusting, poles or pickets are placed, on which the points belonging to the ridges are marked. These points will be joined together in each profile by twine, indicating the different planes of the work.
9th. The form and dimensions of the batteries, either of barbettes or embrasures, will be equally determined by poles or pickets placed at all their angles, and united together by twine in the manner that will be subsequently explained.
10th. For the barbette batteries, the first thing to be done is to establish and to construct the front coupé of the salient of the interior crest, and substitute an interior horizontal crest throughout the extent of the barbette for that situated in the plane of defilement. The necessary adjustments are then made between the slope of the parapet of the barbette and that of the rest of the face, and indicate by means of twine the inters of the terre-plein of the barbette and of its slope with the different planes of the work.
11th. For the embrasures, after having determined their direction, the inters of the cheeks and bottom, with the interior and exterior slope of the parapet, and with its slope; also the slope which terminates the interruption of the banquette throughout the extent of the battery. In the case where the platform is formed more than 0m4 elevated above the soil, a ramp is constructed with its slope, and the inters with the slope from the platform are shown.
12th. After the batteries, the slope of the ends of the traverses and of the passages for entry and exit are constructed.
13th. The traverse will be finished by adjusting its different planes withthose of the parapet. In the particular case, where it was interfered with to make a passage over the banquette, it is finished by reveting the slope passing by the crest of the banquette of the work.
14th. At the passages of entry and exit from the work, the parapets will be finished by the slope of the revetment, whose inters with the different planes of the parapets must be determined.
15th. For each squad of workmen, the distance of the salient of the work to the point on which it will be defiladed must be determined.
MEMOIR.
1st. Object of defilement—which is considered to be dangerous ground, dangerous point, plane of defilement.
2d. Position of the dangerous point relatively to the work which is to be defiladed. Practical method on the ground. Results to which it leads.
3d. On the field this method is not always applicable to an isolated work, and never is so to entrenchments of a great development, such as lines, large têtes-de-pont, &c. By what proceeding is it generally expedient to attempt to fulfill in war the indisputable condition of defilement.
RECAPITULATION FOR THE SUB-LIEUTENANTS OF ARTILLERY AND ENGINEERS.