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REESE LIBRARY ; 
 
 OF THE . ;^ 
 
 UNIVERSITY OF CALIFORNIA. [ 
 Received • ^4<ly>x. ^ . ]8oS^ 
 
 zAccesswns No.SS'S^l^ . Class No. 
 
 
 ^^'•:^ 
 
MANUAL 
 
 Military Field Engineering 
 
 FOR TIIK USE OF 
 
 OFFICERS AND TROOPS OF THE LINE. 
 
 PREPARED AT THE 
 
 
 UNITED STATES INFANTRY AND CAVALRY SCHOOL 
 
 BY THE 
 
 Department of Engineering, 
 
 Capt. Wm. D. Beach, 3RD Cavalry, Instructor. 
 
 Fort Leavenworth, Kansas, 
 July, 1894. 
 
■q - ^ o 
 
 Entered according to Act of Congress in the year 1894, by VVm. D. Beach, 
 IN THE Office of the Librarian of Congress, at Washington. 
 
 Press of Lawton & Burnap, Kansas City, Mo. 
 
PREFACE. 
 
 The necessity existing at the Infantry and Cavalry School for a 
 text book on Field Engineering, including the various military 
 expedients recognized in our service, is deemed sufficient reason 
 for the following pages. 
 
 Most of the subjects treated of in this volume may be found in 
 various military works published in our country during the past 
 twenty-five years, but the fact remains that no one book has cov- 
 ered the required ground, nor has their revision been of very re- 
 cent date; while, at the same time, the new field gun and small 
 calibre rifle have necessarilir modified previously existing profiles 
 of Field Works and Shelter Trenches. 
 
 Access has been had to corresponding publications of the Ger- 
 mans, French, English and Austrians, as well as to our own Offi- 
 cial Rebellion Records and many other available sources, native 
 and foreign. 
 
 It has been the endeavor to limit the scope of this work to sub- 
 jects considered indispensable as a part of a line officer's edu- 
 cation. 
 
 The following Assistant Instructors in the Department of En- 
 gineering, viz : — 1st Lieut. E. A. Root, 19th Infantry; 1st Lieut. 
 W. C. Wren, 17th Infantry and 1st Lieut. T. H. Slavens, 6th Cav- 
 alry have been associated with the undersigned in the prepara- 
 tion of this volume. 
 
 Wm. D. Beach, 
 
 Captain, 3rd Cavalry. 
 U. S. Infantry and Cavalry School, 
 
 Fort Leavenworth, Kansas, July, 1894. 
 
List of Books Consulted in the Preparation of this Work 
 
 Aide Memoire, R. E Vols. 1-2. 
 
 A Move for Better Roads L. A. Haupf. 
 
 Appleton's Cyclopaedia of Applied Mechanics Fo/s. / V. 
 
 Civil Engineering WJieeler. 
 
 Cours de Fortification Passagere De Guise. 
 
 Ecole de Fortification de Campagne French. 
 
 Elements of Field Fortification Wheeler. 
 
 Engineering News Magazine. 
 
 Engineer's Pocket-Book Trautwine. 
 
 Field Fortification Tamer. 
 
 Field Fortification .Hutchinson.. 
 
 Field Works Brackenhia-fj. 
 
 Field Works used in War. (Translation 
 
 from the German) Wilson. 
 
 Good Roads Magazine. 
 
 Gunpowder and high Explosives Walke. 
 
 International Cyclopaedia Dodd, Mead <i- ( v>. 
 
 Journal of the Military Service Institvition 
 
 of the U. S. 
 Journal of the U. S. Cavalry Association. 
 
 Manual for Engineer Troops Duane. 
 
 Manual of Military Engineering Ernst. 
 
 Manual for Railway Engineers G. L. Vose. 
 
 Manuel de Fortification de Campagne. . . . BriaJuiont. 
 Manuel des Travaux de Fortification de 
 
 Campagne par un Capitaine d' Infanterie. 
 
 Manuel de Fortification Plessix and Legrand. 
 
 Manual of Heavy Artillery Tidball. 
 
 Military Bridges Haupt. 
 
 Military Bridges Chester. 
 
 Military Engineering. Instruction in Chatham Course. 
 
 Military Transport Furse. 
 
 Modern High Explosives Eissler. 
 
 Notes on Military Hygiene A. A. Woodhull. 
 
 Official Records of the Rebellion. U. S War Department. 
 
 Organization and Tactics Wagner. 
 
 Pionier Taschenbuch, Berlin, 1893. Official. 
 
 Report of Chief Signal Officer. U. S. 1893. TFar De/xtrf nienf. 
 
 Roads and Railroads Chester, 
 
 Roads and Railroads Gillespie. 
 
 Roads, Streets, and Pavements Gilhnore. 
 
 Temporary Fortification Chester. 
 
 The American Railway ' Scrihncf. 
 
 U. S. Bridge Equipage and Drill Wat- Dcinirl inent. 
 
"rAB^/K OK CONTE^NO^S. 
 
 Chapter. 
 
 
 Page. 
 
 Plate. 
 
 I 
 
 General Principles . . . 
 
 7 
 
 11 
 14 
 
 23 
 31 
 37 
 
 
 II 
 
 Fire, Projectiles, and Penetra- 
 tion 
 
 
 III 
 
 Field Geometry 
 
 ,V- 
 
 IV 
 
 Hasty Intrenchments, Gun Pits 
 and Epaulements 
 
 3, 4 
 
 V 
 
 Clearing the Ground 
 
 5, 6 
 
 VI 
 
 Obstacles 
 
 7, 8 
 
 
 
 
 VII 
 
 VIII 
 
 IX 
 
 X 
 
 XI 
 
 XII 
 
 XIII 
 
 XIV 
 
 XV 
 
 XVI 
 
 XVII 
 
 XVIII 
 
 XIX 
 
 XX 
 
 XXI 
 
 Field Works 
 
 Working Parties 
 
 Revetting Materials and Revet- 
 ments 
 
 Field Casemates and Magazines 
 
 Field Works in Combination. . 
 
 Siege Works 
 
 Defense of Localities 
 
 Use of Cordage and Spars 
 
 Spar Bridges 
 
 Floating Bridges 
 
 Roads 
 
 Railroads 
 
 Telegraph and Telephone Lines 
 
 Demolitions •. . . 
 
 Camping Expedients 
 
 45 
 71 
 
 74 
 89 
 95 
 103 
 109 
 131 
 149 
 176 
 212 
 221 
 235 
 240 
 257 
 
 9-15 
 16 
 
 17,18 
 19, 20 
 
 21 
 22,23 
 24-29 
 30-33 
 34-40 a 
 41-49 
 50 
 51-53 
 
 54 
 55-57 
 58 60 
 
CNIVEBSITY 
 
 NIANTJAL 
 
 MILITARY FIELD ENGINEERING. 
 
 CTTAPTF.Tl T.- Goiioral Priiicii)les. 
 
 1. — Military Field Engineering may be defined to be the 
 art of utilizing the materials at hand for the attainment of the 
 security, effectiveness, health and comfort of an army in the field. 
 
 The modern rifle has vastly increased 'the value of cover both 
 in attack and defense, and rendered necessary the application of 
 the principles of fortification to an army in the field. The result 
 to be obtained in all fortification is to so strengthen a position, by 
 artificial means, that a force may successfully resist or subdue 
 another. 
 
 2. — Fortification is divided into two general classes, viz.; 
 
 (a) — Permanent. 
 
 {h) — Temporary or Field Fortifications. 
 
 With the former this manual has nothing to do. 
 
 3. — The latter division includes three quite distinct classes. 
 
 The first comprises all works devised for the temporary protec- 
 tion of important points such as cities, arsenals, bridges, fords, 
 positions, etc., and are technically known as Field WorJcs. 
 
8 General Principles. 
 
 The second comprises the various devices of the engineer for 
 reducing a fortified place by means of parallels and approaches, 
 called Siege Works. 
 
 The third division relates particularly to the quickly made de- 
 fenses by which an army in the presence of an enemy protects 
 itself ; these are known as Battle Intrenchments or Hasty In- 
 trenehments, 
 
 4. — A Defensive Position is one affording protection from 
 the shot and observation of an enemy and, at the same time, com- 
 manding the ground in front, within range. 
 
 A position of perfect defense is not possible, but the following 
 general principles are to be fulfilled as nearly as circumstances 
 will permit. 
 
 (1) The defenders' position should conform to the special tacti- 
 cal requirements of the occasion* and should be such as to favor 
 the use of their relatively strongest arm. 
 
 (2) It should be made impossible for the enemy to obtain nat- 
 ural cover during his advance. In other words, the position 
 should have a free field of fire. 
 
 (3) The defenders should be protected from the fire and view of 
 the enemy by cover so arranged as not to interfere with counter 
 attacks. 
 
 (4) The advance of the enemy should be hindered by obstacles 
 so arranged that he may be checked while- under the fire of the 
 defenders. 
 
 (5) Communications should be such that the defenders may 
 freely move from one part of the position to another, while the 
 contrary should obtain with respect to the enemy's ground in 
 front. 
 
 The chief requisite of a defensive position is a free field of fire, 
 especially at short and mid ranges. If the position is judiciously 
 selected the field of fire will generally be obtained without much 
 difficulty, but the advantages of the position and the effect of the 
 fire may be enhanced by temporary fortifications. The cutting 
 down of slight ridges which might afford cover for the enemy 
 within effective range or the removal of hedges, fences, etc., may 
 
 *A purely defensive position, for instance, might have its flanks resting on impassable 
 obstacles, and thus be secure from a turning movement, but this same position might be 
 found to be a faulty one were a quick ottensive movement, by the defenders, contem- 
 plated. 
 
General Principles. 9 
 
 sometimes be of more benefit than the actual preparation of de- 
 fenses. 
 
 In the present advanced state of efficiency of fire-arms, artificial 
 cover is, however, of greater importance than ever before. Con- 
 structed in the right place, at the proper time, field fortifications 
 may render indispensable service, while their neglect may insure 
 defeat. 
 
 5. — While formerly it was the special province of the Engineer 
 to lay out and supervise the construction of defensive works, it 
 has now, under the changed condition of warfare, become the 
 work of the Line as well, and it may be laid down as an accepted 
 rule that the defensive arrangements for a given position are to 
 be made by the troops which are to occupy it. 
 
 These changes have affected the art in many ways. The field 
 works now constructed are simpler, ruder, less regular, and less 
 angular than before. An army in presence of an enemy always 
 fortifies, whether in camp, in bivouac, or in line. 
 
 6. — Rapidity of execution renders necessary the adoption of 
 fixed types of works in the exercises in time of peace ; but these 
 types will sometimes be susceptible of modification in their real 
 application. However, even in war, the endeavor should be to 
 approximate to the regulation forms, for they are deduced from 
 experience and observation, and realize, as well as possible, for 
 each particular case, the best conditions of resistance compatible 
 with rapidity of execution. 
 
 The advantage of regulation types is understood at once when 
 it is borne in mind that, upon the battle-field, there should be no 
 hesitation ; everyone should stick to his individual role in order 
 to unite efficiently in combined action. 
 
 Thorough study and frequent practical exercises, conducted 
 methodically, are indispensable in order to escape feeling one's 
 way, with the loss of time that an insufficient instruction renders 
 inevitable. Upon the battle-field a few minutes may decide the 
 fate of armies in each other's sight. 
 
 T. — Fortification, which at first glance may appear to dominate, 
 as representing the "security" and "effectiveness" of an army, 
 the other and apparently less important subjects relating to 
 health and comfort, is, however, so intimately connected with 
 them that neglect of one may render all the others useless. 
 Thus, "bridges," "roads," and "railroads" may, under certain 
 
10 General Principles. 
 
 conditions, relate particularly to the effectiveness and security of 
 an army, in connection with Fortification, while under other cir- 
 cumstances they may be as important as various "camping expe- 
 dients" in the attainment of "health" and "comfort." 
 
CHAPTKK II. Fire, Projectiles and Penetration. 
 
 8. — Fire as regards its direction is classified as follows: 
 
 (1) Frontal, when it is delivered at right angles to the front 
 of the enemy's line, and sometimes so termed when delivered 
 straight to its own front. 
 
 (2) Oblique, when the direction of the fire is at an oblique 
 angle to the front of the enemy's line. 
 
 (3) Enfilade, which is delivered from positions on the prolon- 
 gation of the enemy's line. In this case, the line of fire sweeps 
 the enemy's front. When fire is used to sweep along the front 
 of a defensive line and thus enfilade the assailants as they ap- 
 proach the position, it is known as flanking fire. 
 
 (4) Reverse, when delivered so as to strike troops or lines of 
 defense from the rear. 
 
 (5) Cross, when the lines of fire from different positions cross 
 on or in front of the enemy's line. 
 
 As regards its trajectory it is classified as 
 
 (1) Direct, when delivered at seen objects at moderate angles 
 of elevation — in the case of artillery when delivered at seen ob- 
 jects, with service charges at elevations not exceeding 15° 
 
 (2) Indirect or Curved, when delivered with small arms 
 against an unseen object protected by a seen covering obstacle — 
 in the case of artillery, as above, or, with guns, howitzers or mor- 
 tars with reduced charges at angles not exceeding 15°. Thus 
 firing over an intervening hill at troops sheltered behind it would 
 be an example of indirect fire. 
 
 (3) Iligli Angle, when used at angles exceeding 15°. 
 
 (4) Grazing, when the projectile travels approximately paral- 
 lel to the ground. 
 
 9. — Tlie Artillery Projectiles used in the U. S. Army are 
 shell, shrapnel and canister. 
 
12 FiKE, Projectiles and Penetration. 
 
 81iell. Shell may be classified as common shell and torpedo 
 shell. The common shell is "a hollow cast-iron or steel cylinder 
 with an ogival head closed at one end and filled with powder." 
 The torpedo shell is filled with gun-cotton, or other high explo- 
 sive. Either shell may be characterized as a flying mine, the 
 chief object of which is to destroy material objects at a distance, 
 though the common shell may also be effectively used against 
 troops. 
 
 lO. — 81irax)iiel differs from common shell in being filled with 
 bullets, and having only a sufficient bursting charge to rupture 
 the envelope and release the bullets, which then move with a 
 velocity which the projectile had at the moment of bursting. The 
 bullets are assembled in circular layers and held in position by 
 "separators," which are short cast-iron cylinders with hemispher- 
 ical cavities into which the bullets fit. The shrapnel for the 3.2 
 inch gun contain 162 bullets }^ in. in diameter, and weighing 11 
 to the lb. The total number of bullets and individual pieces in 
 the shrapnel is 201. 
 
 11. — Canister, which is practically obsolete, is made of sheet- 
 iron or tin in the shape of an ordinary can, and is filled with bul- 
 lets held in place by filling the interstices between the bullets 
 with saw-dust, sulphur or rosin; the can is ruptured and its con- 
 tents dispersed by the discharge of the piece. 
 
 12. — The charges in the shell and shrapnel are exploded by 
 means of a combination fuse; by combination fuze is meant one 
 that may be arranged to explode the charge either on impact, by 
 percussion, or at a given time by certain arrangement of the parts 
 of the fuse. 
 
 13.— Field Guns range up to 6000 yds. but will be seldom 
 used at a range greater than 2500 yds. 
 
 14. — Tlie 17. 8. Magazine Rifle, when used as a single 
 loader, has fired 21 aimed shots in one minute, and when used as 
 a magazine rifle, 23 shots in one minute; its range is over 3000 
 yds. and it is sighted to 1900 yds. 
 
 The average heights over which fire may be delivered, are as 
 follows: Man standing i ft. 1 in.; kneeling 3 ft; lying down 1 ft.; 
 field guns 3 ft. 
 
 15.— The following thickness of material may be considered as 
 proof against small arm projectiles at all ranges: 
 
Fire, Projectiles and Penetration. 13 
 
 Sand 30 in. 
 
 Boggy or turfy ground 60 in. 
 
 Gabion filled with earth r 1 
 
 Sand bag well packed, header 1 
 
 " " " " stretcher 2 
 
 Packed snow 6 ft. 
 
 Soft wood 40 in. 
 
 Oak or other hard wood 24 in. 
 
 Grain sheaves piled 16 ft. 
 
 Iron plate /e i^i- 
 
 Steel plate f in. 
 
 Masonry 20 in. 
 
 Against field artillery. 
 
 Earth 10 to 13 ft. 
 
 Snow well packed 27 ft. 
 
 Masonry (for a short time) 40 in. 
 
ClIAPTKH IlI.-^Fielcl GeoinetiT. 
 
 16. — Before proceeding to that portion of field engineering which 
 involves geometry some of its simplest applications will be 
 explained. 
 
 17. — Slopes. The usual description of a slope is by a fraction, 
 the numerator being the height and the denominator the base. 
 Thus, in PI. 1, Fig. 1, the vertical height is l-6th part of the base, 
 and the slope is read as 1 on 6. In Pig. 2., the slope is 6 on 1. 
 
 18. -To lay out a Riglit Angle:— First Metliod. Let 
 A be a point in the line BC, Fig. 3. Lay off from A the equal 
 distances AD and AE. With a radius greater than AD, and with 
 D and E as centers, describe arcs cutting each other at X. Join 
 X with A. Then is XA perpendicular to BC. 
 
 Second Metliod. Find a point such that the distances are 
 in the proportions of 3, 4 and 5: then will the angle included be- 
 tween the two shorter sides be a right angle. Thus (Fig. 4.) with 
 chain or tape measure the distance AD equal to 4 yds. Place one 
 end of tape at D, the other at A, pulling it out and making 
 XD equal to 5 yards, XA equal to 3 yards. 
 
 Tliird Metliod. At extremity of line, as A (Fig. 4.), assume 
 any point as C. Measure distance CA, set a stake on line BA at 
 a distance from C equal to CA, as D. Set a third stake on line 
 CD at X making CX equal to CD. Then will XA be perpendicu- 
 lar to BA. 
 
 19.— To erect a i)eri>endiciilar to a line Croni a i)oiiit 
 Avitlioiit. Let X (Fig. 5) be the point without, then, with X as 
 a center, and a distance greater than XA as radius, describe an 
 arc cutting BC at D and E. With D and E as centers, and with 
 a radius greater than DA, describe arcs cutting each other at Y. 
 Join X and Y. Then will XY be perpendicular to BC. 
 
 20. To bisect a given angle. Let ABC (Fi-. (S.j Ix the 
 
PLATE 1. 
 
 Figure 1. 
 
 Figure 2. 
 
 --x^^RNIA. . Figure 8 
 
 Figure 3. 
 
 B '.D 
 Figure 4 
 
 E c 
 
 X 
 
 Fig^ure 9. 
 
 A C ' 
 
 ' D ' B 
 
 Figure 5 
 
 ^^^-^-.---''A Figure 10 
 
 B D" 
 
 E C 
 
 B D C 
 
 Figure 11 
 
 Y 
 
 
Field Geometry. 17 
 
 angle. With A as a center, and with any convenient radius, as 
 AD, describe an arc cutting AB and AC at E and D. With D and 
 E as centers, describe arcs cutting each other at X. Join X with 
 A. The line XA bisects the angle ABC. 
 
 21. — To lay out an equilateral triangle constructing 
 adjacent angles of GO° and 120°. Let AB (Fig. 7) be a 
 given line. Lay off from B any convenient distance, as BE. Then, 
 with B and E as centers, and a radius equal to BE, describe arcs 
 cutting each other at D. Join D with E and B. The angles DEB, 
 DBE and EDB, are each equal to 60°. The angle AED is equal 
 to 120°. Combining this method with that of slopes an angle of 
 almost any number of degrees can be laid out. 
 
 22. — To lay out an angle equal to a given angle. Let 
 X (Fig. 8) be a point in the line AB, from which it is required to 
 lay out an angle equal to OEC. Fix the points O and C at con- 
 venient distances from E. From X lay off XG equal to OE. 
 Then, with X and G as centers, and EC and OC as radii respec- 
 tively, strike arcs intersecting at F. Join X and F. The angle 
 FXG is equal to the angle CEO. 
 
 23. — To draAv a line parallel to a given line and at a 
 given distance from it. Let AB (Fig. 9) be the given line. 
 From any two points, as C and D, erect perpendiculars. On these 
 lay off the required distance CE and DF. Join E and F. 
 
 24. — To And tlie distance between any two points 
 
 Av lien it cannot be measured directly. First Metliod. 
 
 To hnd AO, take a point B in line with AO and from this point 
 
 (Fig. 10) lay off any convenient angle, as ABC. At D make EDC 
 
 equal to ABC. Measure BC, DC and DE, putting E in the line 
 
 CO. From similar triangles 
 
 BO : BC :: DE : DC .-. BO =: ?^J<^E 
 
 DC 
 
 From the result thus found, substract the distance AB. The 
 remainder is the distance AO. 
 
 Second Metliod. (Fig. 11.) Mark B in prolongation of the 
 line AO. Assume any point as C. Lay off AF, making AC 
 equal to CF: also BE, making BC equal to CE. Prolong EF 
 until a point K is found in line with CO. Measure FK. This is 
 the required distance. 
 
 25. —Areas. To lind tlie area of a rectangle. Multiply 
 the base by the height. 
 
18 Field Geometry. 
 
 To find tlie area of a trai>ezoid. Multiply the sum of 
 the two parallel sides by the perpendicular distance between them 
 and take half the product. 
 
 To find tlie area of a triaii<>le. Multiply the base by the 
 altitude and take half the product. Or, 
 
 Area = \) s (s-a) (s-b) (s-c) 
 in which s is the half sum of the three sides a, b, and c. Or, 
 
 Area = J a b sin C 
 in which a and b are two sides and c the included angle. 
 
 26.— Tlie Field T^evel (PI. 2, Fig. 1) consists of three 
 strips of w^ood A, B and O, each Y^ in. thick and 2 in. w4de. A 
 being 62 in. long, B and C each 44.42 in. The distance between 
 centres on A is 60 in. on B and C 42.42 in. This makes a right 
 angle between B and C. There is a thumb nut at E clamping 
 the arm B to the arm A when the level is used. The screw at 
 F projects, holding the arm B, when folded, up. There is a stud 
 at H, affording an attachment for a plumb bob. There are per- 
 manent joints between B and C, and A and C. 
 
 Fig. 1 shows the level and its joints, plumb bob for reading 
 slopes, and spirit level. Fig. 2 shows side for protracting angles. 
 
 27. — Uses of Tjevel. The level may be used as follows: 
 
 (1) As a spirit-level, the level being on the edge C 
 
 (2) As a square for setting out a right rngle. 
 
 (3) As a protractor. 
 
 (4) For setting off slopes. 
 
 (5) As a mason's level with a plumb bob. 
 
."PLATE 2. 
 
 ^-^^■^■■cM 
 
PLATE 3. 
 
^CNIVEEfelTY 
 
 CHAPTER IT.— Hasty Iiitieiiclimeiits, Gun Pits and 
 Epaiilements. 
 
 28. — The intensity of fire made possible by the fire-arms of to- 
 day renders some form of shelter on the field of battle imperative. 
 Circumstances may occur when advancing lines of skirmishers 
 will find natural shelter, but in most cases artificial cover must 
 be constructed on the spot. The fortifications used on the field 
 of battle depend, as to their position, extent, and use, on the 
 ground and on the tactical advantages to be gained, and, in 
 conformity to this idea, they are constructed at the time of the 
 battle and not before. They are called "Battle'* or "Hasty" in- 
 trenchments and consist of cover for 
 
 (1) Skirmishers lying, kneeling, or sitting. 
 
 (2) Firing line. Supports and Reserves kneeling, sitting, or 
 standing. 
 
 (3) Gun pits and Epaulements. 
 
 29. — PI. 3, Fig. 1, shows the section of shelter trench for skir- 
 mishers — lying down. It gives earth protection to the depth of 
 30 inches, which will stop small arms projectiles, except when 
 'struck in the most favorable spot for penetration. The time with 
 one large spade and one pick — one man — about 15 minutes ; with, 
 small spade, about 20 to 25 minutes. 
 
 30. — ^For men kneeling or sitting in two ranks, cover is gained 
 by deepening the trench already dug to 20 ins. and making it 
 5 ft. wide, thus obtaining a trench having a defense of 1 ft. 4 in. 
 high and about 58 in. thick. Time about 30 minutes — small 
 spade. ^ If single rank is used the trench need only be 2 ft. 6 in. 
 wide. (Fig. 2.) 
 
 31. — Cover standing is obtained by deepening the kneeling 
 trench to 48 in., leaving a step 20 in. high and 3 ft. wide next the 
 front wall of trench so as to facilitate the leaving of the trenches 
 
 3 
 
24: Hasty Intrenchments, Gun Pits and Epaulements. 
 
 to the front and also to serve as a banquette for men firing over 
 defense. The earth defense should thus be 60 in. thick and 2 ft. 
 high; time — infantry spade — 1% to 3 hours. Whenever it is pos- 
 sible the interior slope should be as near vertical as possible. 
 (Fig. 3.) 
 
 32. — When isolated trenches or rifle pits are desired for the use 
 of riflemen they should be made with the same section as the , 
 trenches for cover standing, 2 paces being taken as the length of 
 trench for each man. Should a more thorough shelter be desired 
 than is given by the cover standing the earth defense may be in- 
 creased by digging a ditch in front, care being taken that it is so 
 far to the • front that sufficient distance is given to develop the 
 existing works into the normal field works — i. e., 15 to 18 feet. 
 
 33. — The trenches here illustrated are all made on level ground 
 and are simply types showing the best form and giving general 
 ideas as to the time required to construct cover. They must be 
 varied according to the kind of earth in which they are to be 
 made and such modifications introduced as will strengthen the 
 cover without increasing the time used. The location of trenches 
 depends primarily on tactical considerations, secondarily on the 
 nature of the ground. Sand or stony ground should, if possible, 
 be avoided in selecting the position of trenches. The eye should 
 be placed a distance above the ground equal to the height of the 
 completed parapet in order to locate the trench so as to obtain a 
 clear field of fire to the front. Shelter trenches should always 
 occupy a position giving the greatest development of fire to the 
 front and are generally constructed at the crest of the most 
 abrupt slope. 
 
 34.— In all trenches, except those for skirmishers lying down, 
 intervals in the line should be left for the passage to the front of 
 Artillery and Cavalry — this is especially necessary when the 
 cover standing is used. These intervals will vary in width accord- 
 ing to circumstances but should never be so wide as to preclude 
 their defense by the trenches adjoining the opening. When 
 stones are encountered in digging they should be imbedded in 
 the parapet and well covered with earth, as they splinter badly 
 when struck by bullets or shrapnel fragments. 
 
 35._Wrhen men are required to remain in the trenches for any 
 considerable period they should be provided with splinter proofs 
 or shelters of some kind. Planks, old lumber, doors, etc., may be 
 
Hasty Intrenchments, Gun Pits and Epaulements. 25 
 
 used, in absence of which small poles are available ; they should 
 be laid with one end on the parapet and the other resting on the 
 earth in rear of the trench and then covered with 2 to 3 inches of 
 earth. This defense, while not proof against bursting shells, will 
 protect the men from dropping bullets and shrapnel fragments. 
 (Fig. 4.) 
 
 36. — Ijooi^ Holes may be provided by placing head logs half 
 imbedded in the parapet or resting on sandbags on the crest and 
 leaving spaces beneath for the rifle, or with sandbags, two being 
 laid lengthways to form the sides and two resting on top, as 
 shown in Figs. 6, 7, 8, 9, 10. Brushwood may be used by laying 
 it on top of the excavated loop hole and covering it over with 
 earth ; all loop holes for musketry splay inwards. 
 
 The best practice is not to use head logs or construct loop holes 
 (unless the force is acting solely on the defensive), as their use 
 impels men to hesitate to leave their cover when the advance is 
 ordered. 
 
 37. — When necessary to intrench supports or reserves, the cover 
 kneeling or standing should be used in parallel rows and close to 
 one another. Fig. 5. 
 
 38.— The advantages of the shelters for men lying and kneel- 
 ing are, 
 
 (1) That they present but small difficulties to the advance of 
 Cavalry or A;*tillery over and through them. 
 
 (2) They offer but a small- target to artillery fire. 
 
 (3) They are not often penetrated by rifle bullets. 
 
 (4) They are easily surmounted by their defenders when tak- 
 ing the offensive. 
 
 Their disadvantages are, ^ 
 
 (1) That, being of low mliej^ they often have their field of fire 
 limited by small folds of the ground, although this may be elim- 
 inated to a large extent by care in selecting the site. 
 
 (2) In wet weather they become muddy and uncomfortable. 
 In all intrenchments it is well to loosen the earth in front, to les- 
 sen the effect of shells striking them. It is also necessary to dis- 
 guise the intrenchment by branches, sods, etc., so as to deceive 
 the enemy in regard to their location. 
 
 39.^ — Cover for guns and caissons is obtained in either of two 
 ways :— 
 
26 Hasty Intrenchments, Gun Pits and Epaulements. 
 
 (1) By sinking the guns below the surface of the ground and 
 building a parapet with the excavated earth. Called Gun Pits. 
 
 (2) By building an epaulement in front of and around the gun, 
 the gun in this case resting on the natural surface of the ground. 
 Called Gun Epaulements. 
 
 The Gun Epaulements shown (PI. 4, Fig. 5) may be constructed 
 while the gun is in action, which cannot be done with any form 
 of pit, as pits must be completed before the gun can be put into 
 action. Gun pits of various kinds are shown in Figs. 1, 2, 3 and 
 4.* When the ground is soft, or in plowed fields, the pit is the 
 better construction for use. 
 
 40. — In constructing any earthworks plows may be used to ad- 
 vantage to loosen up the earth. The furrows should begin at the 
 back line of the trench and then return along the front line until 
 the earth is loosened in all the trenches ; two or three plows fol- 
 lowing each other at intervals can be used with advantage. 
 
 * Figrs. 1, 2 and 4, VI. 4, are from U. S. Artillery Drill Regulations. 
 
PIATE 4. 
 
 FIGURE 5. 
 
 j »3 6 Ij (N +3' n-t-s'e" f 
 
 *3'6"' 
 
 ««wa _ 5' Jjiw\»y/<«»«W/'/W!{ 
 
PLATE 5.. 
 

 CHAPTER v.— Clearing: tlie Ground. 
 
 41. — The tools more especially used in the field may be divided 
 into two classes. 
 
 (1) Iiitrencliiiig tools, such as the pick, the shovel (long 
 and short handled), the spade, the picket shovel, and the hunting 
 knife (Infantry equipment.) 
 
 (2) Cutting tools, such as the ax, the hand ax, the log saw, 
 the hand saw, the linked felling saw, the gabion knife (pruning 
 knife), the hunting knife, the bush hook and the wire cutter. 
 (PL 5 and 6.) 
 
 42. — The choice of a defensive position in which the foreground 
 is free from obstructions and favorable to the defenders' fire is of 
 the utmost importance: more or less clearing, however, will 
 usually be necessary. Clearing must be systematically done and, 
 as in all other work, should be undertaken by complete organiza- 
 tions or parts of organizations, under their own officers. 
 
 43. — The extent (theoretical) to which the foreground should be 
 cleared is equal to the effective range of the defenders' weapons. 
 Practically, as wide a space within this limit, is to be cleared, as 
 is consistent with the time and labor available. Brushwood and 
 standing timber most often screen the enemy's advance and steps 
 should be taken to remove them. 
 
 44. — Tlie tools usually employed in felling heavy timber are the 
 ax and the log saw, the former being the most common, although 
 inexperienced men acquire familiarity with the latter more 
 quickly. When using the ax the cut should be commenced on 
 the side toward which it is desired the tree should fall, ropes 
 being used to incline it in that direction, if necessary; if immater- 
 ial which way the tree falls, then attack it on the side toward 
 which it leans; after cutting it a little more than half through 
 change over to the other side and commencing about six inches 
 
32 Clearing the Ground. 
 
 higher up, cut until it falls. In using the saw it may be necessary 
 to wedge the cut or use other means in order to keep the saw 
 free: the teeth should be set wide. 
 
 Both saw and ax may be used, in which case the ax should be 
 used on the side toward which the tree is to fall and the saw on 
 the other side. (PL 6.) 
 
 45. — Trees would ordinarily be cut within a foot of the ground 
 because a greater height would afford cover. A man should cut 
 down a hard wood tree 1 ft. in diameter in 10 minutes and one of 
 soft wood of the same size in one third the time. The hand ax, 
 hand saw, and hunting knife are useful in felling small trees, 
 ropes being attached to bend them, and the cut being made on 
 the convex side. 
 
 Felled timber must be removed, if of such a size as to afford 
 shelter to the enemy. It is utilized in making field casemates, 
 magazines, etc. 
 
 46. — Briisliwood can be cleared at the rate of about 12 sq. 
 yards per man per hour. The men should be extended at about 
 4 paces interval, using the bush hook, hatchet, or hand ax, to- 
 gether with the gabion or hunting knife. 
 
 47. — Grain, grass, or \^eeds must be trampled by men in 
 line, mowed, or burnt. 
 
 48. — Hedges, fences, and walls, if not perpendicular to the 
 front, must be removed. Live hedges should be pulled to one 
 side in order to give the axmen greater freedom. (PI. 6.) Fences 
 can ordinarilly be demolished with axes, walls by battering them 
 down or blowing them down with explosives. (Chapter XX.) 
 
 Buildings may be battered down, burned, or demolished by 
 explosives according to circumstances. In the case of buildings 
 and walls it will usually be necessary to remove the debris, which 
 can be used for filling hollows. 
 
PLATE 6. 
 
 Cutter. 
 
 \:-)f — ' — \,rv4vvvvvvvVvvvwvvvvvTA> VW ^s^' 
 
 J^tnkGcl /^olltnnr S'cLU/ 
 
 Ig. 
 
 .AuQ-Lir. 
 
 o 
 
 "^ Infantry Sncxcte. 
 
 EUROPEAN. 
 
 .M^ 
 

 % 
 
 ""'^^^ 
 
PLATE 7. 
 
 Figure 1. 
 
 Figure 2, 
 
 Figure l^f '^' """ 
 
CHAPTER TI.— Obstacles. 
 
 49. — Obstacles have for their object the holding of the enemy 
 under fire while checking his advance and breaking up his for- 
 mation. 
 
 (1) They must be within the effective zone of the defenders' 
 fire and must be so arranged as to offer the least obstacle possible 
 to an advance from the side of the defense. 
 
 (2) They must be concealed as far as possible from the view of 
 the assaulting party, so that they may come upon them as a sur- 
 prise. 
 
 (3) They must be difficult of removal under fire, and, if possi- 
 ble, should be of such construction as will necessitate the use of 
 tools not usually carried by troops. 
 
 (4) They should, if possible, be so placed as to be secure from 
 the fire of the enemy's artillery, and so constructed that, if struck 
 by his projectiles, they will suffer small damage. 
 
 (5) They must offer no shelter to the enemy. 
 
 50. — Abatis, on account of the ease with which it can be con- 
 structed, is the obstacle most used. 
 
 It consists of branches of trees about 15 feet long, laid on the 
 ground, butts pointing to the rear, all small twigs being cut off, 
 and all large branches pointed and interlaced. The abatis should 
 be 5 feet high. 
 
 The branches are secured to the ground by forks, wire, or by 
 logs laid over the butts of the branches. The use of wire to hold 
 down the branches is recommended, and when used should be 
 also passed from branch to branch so as to form an extra form of 
 entanglement. When more than one row of abatis is used the 
 branches of one row overlap the butts of the next one in front. 
 (PI. 7, Figs. 1 and 2.) 
 
 The abatis most easy of construction is that made by felling 
 
'38 Obstacles. 
 
 trees towards the enemy in such manner as to leave the fallen 
 part still attached to the stump, the branches are then pointed as 
 described before. (Fig. 5.) 
 
 51.— Abatis is often placed in the front of works when the 
 ditch is so shallow as to present little or no obstacle to an assault. 
 When so used they are placed upright and well tamped in. In 
 all cases, especially when small branches are used, it is better to 
 sink the butts in triangular pits, and, when the branches are in 
 place, fill in with earth and tamp well. (Figs. 3 and 4.) 
 
 In all cases where exposed to artillery fire a glacis should be 
 constructed in front of an abatis, so as to protect it from injury. 
 
 52. — Ijow Wire entanglements are formed by driving into the 
 ground stakes about 18 in. long. The stakes should be driven in 
 rows about 6 feet apart, the stakes in each row being opposite in- 
 tervals in adjacent rows. The heads of the stakes are connected 
 by stout wire wound around them. To make this more effective, 
 do not clear the ground, but allow bushes, brush, etc., to remain 
 in place. (Fig. 6.) Use 1 ft. of wire to 1 sq. foot of ground covered. 
 
 5.3. — Ilio-li Wire entanglements are constructed in the same 
 manner, except that the stakes should be at least 4 ft. high, and 
 placed 6 to 8 feet apart. The head of each stake is connected 
 with the foot of the stake diagonally opposite, the line of posts in 
 front and rear being finished off as fence panels with barbed 
 wire. The use of barbed wire is not advised for the interior 
 crossed work on account of the danger and difficulty in working 
 with it. 
 
 Roughly, one yard of wire is necessary for each square foot of 
 entanglement. Ten men can make about 9 square yards of this 
 entanglement in one hour. This work does not require trained 
 men. Wire entanglement, either high or low, is useful on the 
 glacis of field works, as it holds the attacker under fire at the 
 most favorable point. (Fig. 7.) 
 
 54. — Palisades consist of rows of trunks of trees or of squared 
 trunks, 8 or 10 feet high, planted close together and pointed on 
 top. When material is at hand, ribband pieces should be spiked 
 on the inside along their tops about a foot or two below the 
 points to hold them steady. They are used to advantage in the 
 bottoms of ditches or to close the gorge of field works. (PI. 8, 
 Fig. 1.) 
 
PLATE 8. 
 
 1! 
 
 Fioure 1 
 
 Figure 2 
 

Obstacles. 41 
 
 55. — Fraises are palisades arranged horizontally or much in- 
 clined and are much used at the foot of the exterior slope and at 
 the top of the counterscarp; in the first position they point down 
 and in the second upward. In each case, the ribband or strip is 
 spiked on and laid against the ground near the edge of scarp or 
 counterscarp, as the case may be, another one being spiked to the 
 inner end of the fraise, thus the outer ones give good bearing sur- 
 faces and do not break up the crest, and the inner one gives a 
 bearing for staking and tying down. The slopes described above 
 are given so that unexploded shell will always roll away from the 
 parapet. (PI. 7, Figs. 9, 10, 12 and 13.) 
 
 Fraises may with advantage be made of barbed wire in the 
 form shown, care being taken that all wire when finished is on 
 top of the wooden supports. The advantage of this variety of 
 fraise is that it is little damaged by artillery fire and is very diffi- 
 cult of removal. 
 
 When time is pressing fraises may be made of branches of trees 
 with the butts well sunken and staked down. 
 
 5G. — Crow ^^ feet ^ Chevaux-de-frise, and planks full of spiken 
 have been used in the past as obstacles to an advance, but the 
 two former are not now issued for use in our service, and the lat- 
 ter is one not easily made in the field. Such obstacles require 
 much time and material in their construction and are not treated 
 of here, as they do not fall properly in the domain of Field En- 
 gineering ; their value in any event is not commensurate with 
 the difficulty of their preparation. (PI. 8, Figs. 2 and 6.) 
 
 57.— Small Pits are square on the top, 3 feet on a side, and 
 are pyramidal in shape ; they are 2 ft. 6 in. deep, and have a 
 pointed picket driven in the center of each. 
 
 In digging these pits a glacis should be formed in front of the 
 row nearest the enemy and, to avoid filling the pits with earth 
 thrown from the others, the row farthest from the glacis should 
 be commenced first. One man can make 10 pits per day in easy 
 soil. (PI. 7, Figs. 8 and 11.) 
 
 Small pits may be surmounted by a low wire entanglement, 
 making a very serious obstacle. 
 
 58.— Fords may be made impassable by strewing them with 
 harrows, points up. 
 
 59. — A Foiig-ass is a mine so arranged that upon explosion a 
 large mass of stones or shells are projected towards the enemy. 
 (PL 8, Fig. 3.) 
 
42 ()i;sT.\('i.i:s. 
 
 To make a fougass, dig a hole in the shape of a frustum of a 
 cone, inclining the axis in the direction of the enemy, so as to 
 muke an angle with the horizon of about 45 degrees. The sides 
 should splay outwards at an inclination of 12 degrees from the 
 axis. The powder charge is placed in the bottom of the hole — 
 preferably in a box — and in front of this a platform of wood about 
 three inches in thickness : on this are piled stones, brick, etc. 
 The mine is exploded by means of electricity or common fuse. 
 Care must be taken in digging the hole for the fougass that the 
 line of least resistance is in all cases in the axis of the hole, to he 
 sure of tJn'ii, throic the excavated earth upon the crest towards 
 the defenders' side and ram well, allowing earth tj enclose the 
 sides of the excavation in the manner shown in cut. 
 
 Fougasses are useful in defending boat-landings, roads, etc. 
 
 The following empirical formula may be taken for determining 
 the charge of powder for fougasses : P = jS^,, in which P and s 
 represent the weight in pounds of the powder and stone. 
 
 When broken up, a cubic foot of limestone weighs 96 lbs. 
 
 GO. — Ijaiid Mines are small mines placed in the line of ad- 
 vance of the enemy and exploded either by electricity or fuse 
 from the defense. The small mines are made by digging holes 
 from 2 ta 3 yards deep, placing the charge in a box in a recess 
 excavated in one side of the hole, and refilling with the excavated 
 earth, tamping well. The wires are carried back in a small trench 
 to the work. In common earth, the charge for 2 yards deep is 
 about 25 lbs., and for 3 yards deep about 80 lbs.; the diameter of 
 the crater formed will be about twice the depth of charge. 
 
 (Fig. 4.) 
 
 01. — Barricades are used to prevent the passage of the 
 enemy through roads, streets, and defiles generally. 
 
 They may be made of any material at hand, paving stones, over- 
 turned carts, barrels filled with earth, stones, and articles of like 
 nature. They should be built so that a passage is always left for 
 the defenders, but means should be at hand tj close the opening 
 quickly — a wagon may bo used for this purpose, being drawn 
 away from the openinn- w lien a passtinc is desired. 
 
 The houses on either side should be looi^-holed and uschI to 
 flank the defense. Overturned wagons, broken furniture aiul 
 debris from the adjacent houses make a very good <)J><itavh' ami 
 should be placed in front of the Ijanicadc 1 > wai.l oil" caxalry 
 charges. (Fig. 5. ) 
 
PL ATE. 9. 
 
CHAPTER Til. Field Works. 
 
 02. — When a position is to be held for a considerable period and 
 when time is available, more deliberate defenses than the Hasty 
 or Battle Intrenchments (Chapter IV) are constructed. These are 
 known as Field Works and usually require a minimum of 6 hours 
 for construction. The conditions to be fulfilled, besides those 
 necessary for a defensive position (Chapter I), are 
 
 (1) That they must afford protection against both rifle and ar- 
 tillery fire. 
 
 (2) That they must be of suitable size for the garrison that is 
 to occupy them. 
 
 (8) That they should have suitably constructed casemates to 
 shelter the garrison at night. 
 
 Field works may be constructed for the defense of a single ob- 
 ject, as a bridge, a ford, etc., or they may occupy the key points in 
 a long line of defense, in which case they should be located so as 
 to afford mutual protection, the intervening space either being 
 left open or occupied by shelter trenches. 
 
 Before proceeding to the study of Field Works, a brief synopsis 
 of the technical terms used in connection with them will be 
 necessary. 
 
 63. — A Parapet is a bank of earth thrown up to cover the 
 defenders while firing. 
 
 64.— Tlie Trace of a work is its outline in plan: the term is 
 often applied to the horizontal projection of its interior crest. 
 (PL 9, Fig. 1.) 
 
 65. — Tlie Profile is a cross-section of the work made by a 
 plane perpendicular to the interior crest. (Fig. 2.) 
 
 In the profile, the various parts are named as follows: 
 
in FiKLi) Works. 
 
 a. Banquette slope, e. Exterior slope, d. Ditch. 
 
 b. Banquette tread, f. Berm. i. Interior t^loiH" of glacis. 
 
 c. Interior slope. g. Escarp. k. Glacis. 
 
 d. Superior slope. h. Counterscarp. t. Trench. 
 
 (>(). Tlie Intorior CiH'st is the intersection of the Interior 
 and Superior elopes: somc'iincs cjilled the mjigistral line, ('^a'' 
 Fig. 1.) 
 
 07. V\\r Kxterior Crest — that of the Superior and Exterior 
 sloix's. c'l)" Fig. 1.) The thickness of parapet is the horizontal 
 distance between interior and exterior crests. 
 
 08. — A Traverse is a bank of earth inside a work to protect 
 some poition of it from direct fire. When the protection afforded 
 is from revet: c tire, the traverse is sometimes called a Parados. 
 (Figs. 3 and 1.) 
 
 09. All Kinhrasiire is a revetted opening in the parapet, 
 through wliich tield guns may tire. It is said to be Direct or 
 ()i)li(iu(^ aocoi-ding to whctlKM- its axis is perpendicular or inclined 
 to the JiiK^ of ])arapet. 
 
 70. A (inn Bank nv ( im TG|iaii1r mi »ii is a raided 
 mound, by means of which held guns may hre over the i)ara|:et. 
 Guns thus placed are said to be "en barbette." 
 
 The relative advantages of Embrasures and Gun Banks are as 
 follows: — 
 
 Embrasures afford greater protection to the gunners, but 
 
 (a) They afford a very limited field of lire. 
 
 (b) They weaken the parapet and require frequent repairs. 
 
 (c) The place of the gun when not in action cannot well be 
 used by Infantry. 
 
 The conditions as to Gun Banks are the converse in each case. 
 
 71. — Tlie Coniniaiid of a work is the height of its interior 
 crest above the ground on which it is constructed, ("m" Fig. 2.) 
 
 72. — Its Relief is the height above the bottom of the ditch, 
 ("o" Fig. 2.) 
 
 73. — Tlie l*lane of Site is a plane tangent to the ground 
 on which the work is constructed. 
 
 14, — Tlie Terre])leiii is the surface of the ground inside the 
 work and does not, of necessity, coincide with the plane of site, 
 since the whole interior of the work — /. c, the terreplein may l)e 
 lowered for the purpose of securing more cover. 
 
Field Works. 47 
 
 When the banquette tread is more than two feet above the ter- 
 replein, its slope may be stepped with fascines or planks: this has 
 the advantage of giving more interior space but tends to produce 
 confusion on the part of the defenders, especially in a night 
 assault. 
 
 75. — Tlie interior slope is usually made as steep, up to four 
 on one, as the revetment will stand. 
 
 70. — Tlie superior slope is necessary in order to secure the 
 best lire effect on the ground immediately in front of the work. 
 It weakens the parapet near the interior crest, however, and this 
 defect increases as the slope is made steeper, hence, it should be 
 as slight as is consistent with good tire effect. 
 
 The degree of this slope is regulated by the principle that fire 
 from rifles resting on its surface should not pass more than three 
 feet above the glacis, or, when there is no glacis, above the outer 
 edge of the ditch. It will thus depend on 
 
 (1) The command of the work. 
 
 (2) The inclination of the plane of site. 
 
 (3) The distance from the interior crest to outer edge of ditch. 
 The slope should not exceed one on four; one on six (normal) is 
 
 better, and then, if necessary, make a glacis of the requisite 
 height. 
 
 77. — Tlie exterior slope should be as gentle as two on three, 
 if possible, owing to the fact that steeper slopes are soon destroyed 
 by artillery fire. ^ ' 
 
 78. — Tlie Berni may be as great as 6 ft. in width; ordinarily it 
 would not be greater than 2 ft., while in favorable soil none may 
 be left at all. 
 
 Advantages of berm. 
 
 (1) It relieves the edge of the ditch from the weight of the par- 
 apet and thus prevents caving, in loose soil. ^cf^i- 
 
 (2) It enables the parapet to be thickened. ffrx ^' /> '^/^ 
 
 Disadvantages: vC^ o^ -^TV 
 
 (1) It affords a footing in an assault. (This, however^lHl^.3^oy^NIA. 
 
 partially remedied by use of obstacles.) ~ 
 
 79. — The slope of the escarp and counterscarp should be equal 
 
 to or greater than the exterior slope, the latter being as steep as 
 
 the earth will stand. 
 
18 Field Works. 
 
 80. Tlie CMcicis should be parallel to the superior slope, in 
 order to get the best fire effect from the crest. 
 
 81. — If the parapet does not require much earth, and the ditch 
 is required as an obstacle, it may be made triangular in cross sec- 
 tion. This form gives the greatest depth and prevents the assail- 
 ants from forming in the ditch, but it is difficult of construction. 
 Eight feet may be taken as the cxticnic depth of ditch and twelve 
 feet as the extreme height of ])araiJot. The width of the ditch 
 varies with the amount of earth required — 1'2 ft. at tlie top being 
 a minim u in. 
 
 A parajrt with trench and ditch affords cover in the shortest 
 time possible: each foot of depth in the trench means 2 ft. of 
 cover, plus the additional protection afforded by the earth from 
 the ditch. 
 
 A parapet with ditch alone affords greater cover to the ground 
 in rear and better command of ground in front, but its height 
 makes it more conspicuous. 
 
 82.-"Ref erring to traces of various works (PI. 9, Fig. 5.)— 
 
 a, is a salient angle, 
 a' is a shoulder angle. 
 
 b, is a re-entrant angle. 
 
 c, c, c, are faces. e, e, is the gorge. 
 
 d, d, d, are flanks. f, is the capitnl. 
 
 83.— Field Works are classified wuth reference to their 
 trace, as 
 
 (1) Open, which have thick parapets on exposed sides, the rear 
 or gorge being open. 
 
 (2) Closed, in which the thick parapet is continuous. 
 
 (3) Half -Closed, which only differ from the "open" in that 
 the gorge is closed by obstacles, stockade work, or shelter 
 trenches. 
 
 Advanced works within rifle range of the main defensive line, 
 as well as those in positions where the flanks are secure (as a 
 bridge head), should usually be "open." Works in main line and 
 advanced works beyond rifle range should be " half -closed; *' those 
 in isolated positions or on the flanks of a defensive line— "closed." 
 
 Open works have the advantage over closed, of affording greater 
 freedom of movement to the defenders, and, in the event of cap- 
 ture, of being exposed to fire and assault from the works in rear. 
 
PLATE 10. 
 
Field Works. 51 
 
 Closed works, while affording greater protection from assault, 
 are liable to have their parapets exposed to enfilade or reverse 
 fire, besides which the available interior space is much reduced. 
 
 84. — Forts and Redoubts (Closed Works) are distinguished 
 by the former having re-entering angles, thus affording defense 
 of the ditch from the parapet, both conditions being lacking in 
 redoubts. 
 
 Redoubts, as compared to forts, are of simpler trace, do not re- 
 quire so large a garrison, and afford better frontal fire; but, as 
 they have no ditch defense (unless caponiers and counterscarp 
 galleries are constructed), they should be traced to support one 
 another. 
 
 85. — With respect to caponiers (PI. 20) and counterscarp galler- 
 ies — the former, if sunken, as is usually necessary for protection 
 against artillery fire, may, become untenable in rainy weather; 
 while communication with the latter is difficult and may by the 
 enemy, be rendered impossible. The objections to these forms of 
 ditch defense are so great, and their use so limited, where proper 
 frontal fire and obstacles are possible, that their construction is 
 seldom necessary. 
 
 86. — Tlie Sector of Fire is a term used to designate the an- 
 gular space in front of a work which is swept by its fire (30° on 
 each side of a perpendicular being considered the limit of oblique 
 rifle fire.) Thus, a straight line of parapet has a sector of fire of 60° 
 (PI. 10, Fig. 1), while, in a redan, it varies with the angle at the 
 salient. With a salient of 120°, the sector of fire is evidently 120° 
 (Fig. 2), with a 60° salient, there will be an undefended space of 
 60°. (Fig. 3.) This undefended space may be done away with by 
 blunting the redan. (Fig. 4.) A redan with shoulder angles (Fig. 5) 
 furnishes a ditch defense in front of the shoulders and doers away 
 with part of the dead space in front of the salient but it is diffi- 
 cult of construction and is not usually resorted to. 
 
 87. — For reasons given in Chapter XI, it is often desirable to 
 place the guns outside the work; in which case some plan like 
 Fig. 6, may be adopted, the single line representing a shelter 
 ti-ench. 
 
 88.— Defilade of Field Works. In order that Field Works 
 may fulfill the condition of screening the occupants from the fire 
 aiul \ lew of an enemy, the problem of defilade arises. 
 
VJ Field Wokks. 
 
 This may be defined as the operation of regulating the direction 
 and command of the earth cover so that the interior of the work 
 is protected from the direct tire of an enemy. 
 
 The problem resolves itself into two distinct parts — 
 
 (1) Defilading in plan. 
 
 (2) Defilading in section. 
 
 89.— ^Defilacliiiji' in i)laii. Tliis involves the selection of the 
 trace of the work (its ijosition having been previously chosen.) 
 The trace will vary with the plane of site, the terrain in the im- 
 mediate vicinity, the x^i'oximity of high ground that the enemy 
 may occupy, and the time available for construction. A plane of 
 site sloi)ing to the rear is obviously the easiest to defilade, and 
 one sloi)ing toward the enemy, the most difficult. Salients should 
 occupy commanding ground, the lower portion being taken for 
 the re-entrants or for th« gorge. The longer faces of a work 
 should lie in the direction of lower or inaccessible ground, so that 
 they connot be enfiladed. 
 
 With commanding ground in front, the work is more difficult 
 to defilade in proportion to its depth, therefore, have longer faces 
 opposed to the high ground and make the work as shallow as is 
 consistent with other conditions. 
 
 As a rule, the longer faces of a work must lie so that the de- 
 fenders can bring as direct a fire as possible in the direction of 
 expected attack. 
 
 All the foregoing conditions as to defilading in plan, cannot, in 
 the usual case, be satisfied, but the object to be attained must be 
 kept constantly in view, and, in selecting the trace for a work, an 
 officer's ability will be shown by the skill with which he harmon- 
 izes the various diverse requirements. 
 
 After the careful selection of the trace, as already indicated, 
 and marking it by pickets, the problem is completed by defilading 
 the proposed work in section. 
 
 90. — Deflladiiig in Section. With a horizontal site and 
 only level ground toward the enemy, a constant command of 8 ft. 
 is sufficient to protect the whole interior of the work. 
 
 On an irregular site, or when necessary to place a work in a 
 position commanded by higher accessible ground, the necessary 
 protection of 8 ft. may be attained in one of three ways— 
 
 (1) By raising a parapet. 
 
 (2) By lowering the terreplein. 
 
PL ATE 11 
 
 Figure 1. 
 
 Figure. 2. 
 
 ^^ 
 
 S^l^^^ 
 
 
 c^'f^fc 
 
 tL 
 
 ^-'-T^ 
 
 
 Figure 3. 
 
 '^0^^^^^ -/K 'i 
 
 ^^^; 
 
 ^R 
 
 Figure 4 . 
 
 ^T;^— :: ^l^-^^^^^Zj^^, 
 
 
Field Works. 55 
 
 (3) By use of traverses, parados, bonnets, etc. 
 
 To determine how much protection is needed, suppose, for ex- 
 ample, the proposed work is a lunette. Plant poles at the salients 
 of sufficient length to reach the interior crest of completed work. 
 Place two pickets at the gorge, about 6 ft. apart, one on each side 
 of the capital and a third 8 ft. to the front. Tie a string to the 
 rear pickets, 3.5 ft. from the ground, the string passing round the 
 third stake. (PI. 11, Fig. 2.) Taking position behind the horizontal 
 string, have an assistant move the string on the forward picket 
 until it comes into the plane fixed by the eye, the horizontal 
 string and the highest point of the dangerous ground. This plane, 
 which is now established by the string triangle, is called the tan- 
 gent plane. A plane parallel to this and 4.5 ft. above it is known 
 as the plane of defilade. (Fig 1.) The proper height of parapet at 
 the salient and shoulder angles is now fixed by sawing off the 
 poles 4.5 ft. above the points in which the tangent plane cuts 
 them. This will evidently give 8 ft. cover at the gorge, at which 
 point the height of parapet of the flanks is 8 ft. 
 
 If it is found that the required height of parapet exceeds 12 ft., 
 the plane of defilade may be lowered not to exceed 1.5 ft. This 
 will still give 6.5 ft. protection at the gorge. 
 
 If this proves insufficient, either traverses must be resorted to 
 or the terreplein at the gorge lowered. 
 
 91. — To defilade a Avork from two or more lieiglits, 
 the plane must be tangent to the two heights to which angles of 
 elevation are the greatest. As three points fix a plane, it follows 
 that the tangent plane would usually contain but a single point 
 of the string at the gorge, hence, the problem is solved by revers- 
 ing the string triangle — i. e., fixing the apex at the gorge 3.5 ft. 
 above the ground, and the two extremities of the base within the 
 the proposed work and far enough apart to allow the two heights to 
 be seen between them. An assistant at each of the forward stakes 
 adjusts the string as directed. (Fig. 3.) The problem is then com- 
 pleted as in the previous case. 
 
 92. — It is sometimes advisable, when a single plane of defilade 
 gives too great a command, to use two planes ; the portion of the 
 interior of the work on the side toward H (Fig. 4) being defiladed 
 from it, and that on the other side from the height H'. This 
 method exposes the faces and flanks to reverse fire and renders 
 traverses (parados) necessary. 
 
.'it') |-'l 1,1.1) WolJKS. 
 
 J>:3. — The lieio^lit of a traverse (which should be such that 
 a shot grazing it will pass 2 ft. above the parapet it is to cover) is 
 found as follows : 
 
 Assume that the traverse is to be on the capital of a lunette. 
 
 The problem of direct defilade with two planes having been 
 solved, and the poles at angles of the works having been sawed off 
 to indicate the proper height of interior crest in order to defilade 
 the work as far as the cai)ital, the height of traverse to protect a 
 flank from reverse fire is found thus : Measure down from the 
 tops of the poles at the extremities of the flank any convenient dis- 
 tance, as 3 feet,* mark the points and connect them by a string. 
 This string and the opposite height determine a plane which will 
 cut rods held vertically on the capital, at a distance of 5 feet below 
 the required top of the traverse (2 ft. plus the distance measured 
 down on the poles). Proceed in a similar manner, using the other 
 hill and its opposite flank. The greater of the two results fixes 
 the height of that portion of the traverse. In the same manner, 
 its height to protect the faces from reverse fire may be found. 
 By reference to Fig. 4 this will be readily understood. 
 
 This method, while not absolutely accurate, will give results 
 near enough for all jn-actical purposes, with the error on the side 
 of safety. Traverses or Parados are the usual protection against 
 reverse and enfilade Ww. and. although sometimes used to protect 
 parts of a work from direct lire, this is usually attained either by 
 raising the para,pet, by low^ering the terreplein, or by both these 
 methods combined. 
 
 94. — Profiling. After the trace of the work has been decided 
 upon, the problem of defilade solved, the poles at the angles cut 
 off as indicated, and the cross saction of the parapet decided 
 upon, the next step is to erect profiles which shall correspond to 
 this cross section. Thes3 profiles are, if practicable, to be made 
 of strips or battens, 1 in. x 2 in. and placed at intervals of about 10 
 yds. along each face and flank, as well as at each angle. 
 
 For parapets not over 6 ft. in height, stakes may at once be 
 driven into the ground and strips nailed to them, but for higher 
 parapets it is more convenient to make the profile on the ground, 
 merely driving short pickets in ijlace of the long stakes in the 
 first instance. When completed, the profile is up-ended and 
 
 * The idea being to have the string behind which tlie obstivtr stands, when looking 
 towards the height, at about the level of the eye. 
 
PLATE 12. 
 
PLATE 13 
 
Field Works. 61 
 
 nailed to the pickets. (PI. 12, Fig. 1.) If strips cannot be ob- 
 tained, the entire profile, except the uprights, may be made of 
 twine. The profiles at the angles of the works, known as oblique 
 or angle profiles, will evidently differ from the others in length, 
 while their height, on level ground, remains the same. The posi- 
 tion of any point of the angle profile, as, for example, the exterior 
 crest, is fixed by finding the intersection of the prolonged exterior 
 crest lines of the face profiles. This result is accomplished by 
 standing on the farther side of the sacond profile from the angle 
 and lining in an assistant who holds a rod vertically at the angle, 
 one end of the rod resting on the ground. Aftar the profiles are 
 in place, twine should be stretched between them to indicate the 
 various crest lines. The outer edge of the battsns marks the 
 extent of the fill, except in the case of the intarior slope, which 
 is marked by the inner edge when the slope is to be revetted. 
 
 95. — Calculation of Dinieiisioiis of Eartli works. The 
 command of the propos3d work having been fixed by the require- 
 ments of defilade, and the thicknesH by the character of fire ex- 
 pected, it becomes necessary to calculate the dimensions of the 
 excavations^ so that they ivill furnish enough, and no more, 
 earth than is required. The size of embankments and trench are, 
 by the nature of the problem, fixed, as is the depth of ditch, hence 
 the only variable is width of ditch, which is found as follows: 
 
 Assuming the relief to be constant and the profile, for example, 
 to be as shown in PL 13, make a sectional sketch of the proposed 
 work at any point except an angle. Calculate the sectional area 
 of parapet, glacis, and trench, in sq. ft. and from the sum of the 
 first two subtract the last: the remainder divided by the assumed 
 depth of ditch, in feet, will give the mean width of ditch, 'from 
 which, knowing the slope of escarp and counterscarp, the width 
 at top and bottom can readily be found. 
 
 96. — Eartli in enibaiiliineiit occupies, for a time, about 
 one-twelfth more space than it did originally, but this increase is 
 not usually taken into account in the computations for ascertain- 
 ing the width of ditch. When the relief of a work is not constant, 
 it is evident that, in order to get the proper amount of earth, 
 either the depth or the width of ditch must vary. On account of 
 the labor required in raising earth, the limit of depth is taken at 
 8 ft.; for a similar reason, the maximum height of parapet is 
 taken at 12 ft. Whatever the depth of ditch assumed, it is always 
 
(J2 FlKLJ) \V()IM<s. 
 
 constant. The required width at any point is found by means of 
 a section of the work, as ah-eady explained, a section near the 
 extremities of each face determining the width of ditch for that 
 entire face. 
 
 07. — An excess of earth will occur at the salients ami a defi- 
 ciency at the re-entrants, althouijh this may be partially obviated 
 1)\ niakiiii;' tlic slioNclcrs tliiMw towni'd the re-entrants. 
 
 1)8. I)i-aiiuit»'c <>r tin* trench must be provided for at the 
 time the work is constructed. If the fall is toward the goruc an 
 open drain will suffice, but, if in any other direction, a covered 
 drain (PI. 50) should be left t3 carry the water to the ditch. 
 
 Construction of Fieldworks. The details of construc- 
 tion and dimensipns of earthworks will change with varying re- 
 quirements and soil, but there are certain general principles that 
 should be followed in all. 
 
 99.— As to in'ofile : The Normal (PI. 14, Fig. 2) fulfills the 
 conditions as to simplicity, protection against field artillery (in 
 most s )ils). (• oinmand of the ground in front, and cover standing, 
 ill \]\r trench. The trench is stepped and steps revetted to facili- 
 tate' mounting the banquette, while the berm is omitted to deprive 
 the assailants of a foothold. The command may be increased 
 either with or without constant ijelief, the parapet thickened or 
 reduced, and the trench made into a casemate without changing 
 the type of this prcflle. 
 
 lOO. — As to g;arrison : For ordinary field works, the garri- 
 son is usually computed at 2 men per yard of interior crest ; but 
 for isolated works, this estimate should be increased by one-half. 
 Embrasures and gun-banks each reduce the interior crest line 
 available for troops, by 5 yards. 
 
 lOl .— As to layina* out tasks: Cutting lines must be 
 marked l)y tape or pick, computations made, and the exact size 
 of the task for each relief determined in accordance with the 
 rules given in Chapter VIII. 
 
 As an example of laying out tasks, assume that an earthwork 
 with normal prohle and constant command of 6 ft. is to be made 
 on a level site. 
 
 Before work is commenced, the outer and the cutting lines of 
 ditch and trench must be marked. As fatigue parties cannot be 
 expected to excavate earth and at the same time preserve the 
 proper slopes, the usual method followed is to dig vertically as in- 
 
PLATE'14 
 
 ^B-d/Ui/ . i^\ Figure L 
 
   NORMAL PROF/LE 
 
 SHOW/NG TASKS. 
 
 s. 
 
 itUndd 
 
 ' ^V€^ 
 
 -fOO/^. 
 
 ^^(^•md CdiM'udtjoilj 
 
 
 
   - • 
 
 ' MB^fs/. 
 
 To L-S^ 
 
 ;^^-"^^^^:i 
 
 EARTH f/lOfif 
 
 rHeuEF. 
 
 rHEU£F. \3'/i£uqF. 
 
 Spades 
 
 PCcJ<^ 
 
 Sh<,veU%)^rRel 
 
 2Rec. 
 
 5^^ 
 
 Oitch / 
 Xrehc/i { 
 
 .20 d 
 
 .../ 3 
 
 
 -..20 d 
 
 ,r.ao.,. 
 
 -..2c?... 
 
 :~:7S.': 
 
 /oo. . 
 
 ,S5.^. 
 
 rr^_ 
 
 '.".z'd"' 
 
 -Wxd': 
 
 
 
 
 
 I - 
 
 
 
 
 . ../Q 
 
 .aj'/-^ 
 
 8(k.. 
 
 
 
 J.60... 
 
 ...C5^-.. ...35-^.\--^0... 
 
 -^0-'- 
 
 ...25-.. 
 
 
 ~1 
 
 
 
 PI. 14, Table, 2d relief, Trench, in8ert'^2(kl"an(l"I0s"ancl for total"33^' 
 read "63.'^ 
 
PLATE 15. 
 
 FIG. 1 
 
 FIG. 2. 
 
 ,._ -/300 f.o 3000 yards ^'^ — , /^ 
 
 •A: 
 
Field Works. 67 
 
 dicated by the cvitting lines and afterward form the slopes by 
 cutting off the steps. 
 
 The cutting lines for the task of the 1st Relief would be made 
 on the ground, as indicated in section and plan. (PI. 14, Fig. 1). 
 The 1st Relief having finished, cutting lines for task of 2d Relief 
 would then be marked out, and finally, the 3d Relief would com- 
 plete the slopes of ditch and parapet, and finish any work not 
 completed by the other reliefs. 
 
 When not practicable to revet the banquette and trench steps, 
 the risers may be sloped back at about six on one. 
 
 When necessary to throw earth more than 12 ft. horizontally, 
 extra shovelers should be provided at the rate of 1 to each 2, or 2 
 to each 3 diggers, depending upon the soil and the distance it is to 
 be thrown. 
 
 102. — Gun Banks, when made, are usually placed in the 
 salients, for the reasons that the guns will have a greater field of 
 fire and it is at this point that the earth of which they are made is 
 in excess. PI. 12, Fig. 2 shows a gun-bank on a straight line of par- 
 apet and Fig. 3 one at a salient. The top is horizontal and 3.5 ft. 
 below the interior crest : this distance may vary, however, for dif- 
 ferent pieces. All slopes are one on one, except the ramp, or road- 
 way leading up to the bank ; this may be as steep as one on four, 
 but a gentler slope is better. The width of ramp should be 8 ft. 
 The level surface of the bank extends back 24 ft. from the parapet 
 and a log or fascine is half sunken and picketed near the front, for 
 a hurter. The width of bank for a single gun is 15 ft. At a salient 
 (PI. 12, Figs. 3 and 4) the angle is filled in by a straight revetment 
 from 6 ft. to 15 ft. long and the superior slope reduced to corra- 
 spond to lines joining its extremities with the exterior crest salient. 
 This forms what is known as a "pan coup^.'' 
 
 10.3. — Embrasures for field guns would be used in positions 
 where the fire is required to he in one direction only ; for example, 
 to sweep a road, bridge, or ford; or in the flank of a work to 
 cover ground in front of an adjacent work. 
 
 PI. 15, Fig. 1, shows the horizontal projection and the section of 
 an embrasure. It is made at the same time as the parapet, by 
 making the sole " s " parallel to the superior slope. The cheeks, 
 "c, c," are vertical<l© the throat, "e," and have a slope of one on 
 one at the other extremity ; their height should never exceed 4 ft. 
 
 The usual method of forming an embrasure is to stretch a string 
 
()8 Field Works. 
 
 alon^^ the lino of tiro : at tlio tliroat lay off 1 ft. on oacli sido of it, 
 and at a distanco of 5 ft. from tho throat lay otf 1.") ft. in a similar 
 manner. Ki^iit linos joinini:- tho oorrosijondin^;' points so doter- 
 nnnod will mark tho oiitor linos of tho solo, which will si)lay one 
 on ton. Kaoh throat i^ahion is vertical, the extreme ones hoin<i- in- 
 clined thi-oe on one: tlio slope of the intermediate^ on'/s is secured 
 l)y alij^'nmont to]) and hottom on tho extreme ones. Haoh u-;d)i()n 
 is anchored independently (,f the otliers. so that one may he torn 
 out without serioiislv injnrinu' tlic ond)i'asui-e. 
 
 1 04. "By tho MiM-ioii is meant that portion of the parapet be- 
 tween two end)i'asures and al)o\'e the soles. Knd»rasiires should, as 
 a rule. no\'er be (dosef toii'ethor than ir)ft.. ot lierwise thi' merlon is 
 too much weakened. 
 
PLATE 16. 
 
 Fig. 1 
 
 F-g-/2- 
 
 Fig.3. 
 
 .Q<..Q.. :(J..O...-Q-.i.>a.r.g^ 
 
 '4'^' 
 
 
 
 
 r 4-' 
 
 5' 
 
 5' 
 
 5' 
 
 5' 
 
 ^3!i 
 
 Fig.4 
 
 
 
 9 
 
 ^. 
 
CHAPTER VIII.— Working Parties. 
 
 Occasion may arise, as, for example, at night, in the presence of 
 an enemy or even with a large working party, when a well-estab- 
 lished system of taking and handling tools, distributing and reliev- 
 ing working parties, etc., will be of paramount importance. 
 
 105. Organization of Working Parties. The nature 
 of the required work having been decided upon, the estimate of 
 and the application for the requisite number of men and tools de- 
 volves upon the otRcer charged with its execution. 
 
 A working party of the requisite strength (which should include 
 a reserve of 1-lOth) should be furnished, as far as possible, from a 
 complete organization, a company, a battalion or brigade, and not 
 from detachments of different organizations. 
 
 106. — Ilesponsibility. The party should be divided into re- 
 liefs and the task each is to accomplish made plain before it begins 
 work. The officers and non-commissioned officers of the working 
 Ijarty are responsible for the amount of work done. 
 
 107. — Tali:ing Tools. The first relief, having been formed 
 in single rank with rifles slung across the back, is marched to the 
 park where the tools have previously been laid out, either in rows 
 (PL 16, Fig. 1) or in heaps. (Fig. 2.) The relief in the former case 
 is advanced in line to the row and each takes a pick in the left 
 and a spade in the right hand; in the latter case the party in 
 column of files is marched between the piles, each in turn re- 
 ceiving a pick in the left and a spade in the right hand. The 
 relief is then marched in column of fours or twos to the point 
 where the work is to begin. 
 
 108. — Carrying Tools. In carrying picks and spades the 
 handles are grasped near the iron, which is held vertically, the 
 arms extended and the hands close to the side. In turning, the 
 point of the pick should be lowered and the blade of the shovel 
 
T2 WOKKINCJ PAiniKS. 
 
 raised, and when marching, either in line or in cohuiin, the han- 
 dles should be splayed outward, in order to ])i(>v('nt interference. 
 The necessity under certain circumstances of preserving silence 
 makes the above precautions important at all times as a matter of 
 trainin^^ 
 
 109. Kxtciidiiio; the AVorkiiio- Paity. When the first 
 relief approaches the designated point it is halted, then broken in- 
 to colunm of files and direction changed, if necessary, so that the 
 head of the column approaches in a direction parallel to and about 
 3 yds. in rear of the tape marking the front edge of proposed exca- 
 vation. (Pig. 3.) When the leading file is opposite his place the 
 command is given : 
 
 (1) On right {or left) into line at two fxici's interval. (2) 
 Mareli. (3) Detachment. (4) llall. 
 
 The command "halt" is given when the leading hie is 1 yd. in 
 rear of the tape. While the line is forming, the correct positions 
 are at once taken, as follows : 
 
 Each man on arriving at the line extends his arms horizontally, 
 holding them thus until his own position and that of the man fol- 
 lowing him are established by touching hands. As soon as each 
 man has his position he drives his pick into the ground on the 
 left of his own task and lays his shovel on the ground, parallel to 
 and at a distance in the rear of the tape equal to the width of his 
 task from front to rear. 
 
 Rifles are then unslung. belts and canteens removed, and all 
 having been placed on the ground three paces directly to the rear 
 of task, butts of rifles toward the front, tlie men sit or lie down be- 
 hind their shovels until the order '■('onnncncc trorJ:." 
 
 no. — Extension of 2d and 3d Reliefs. Each man of 
 the 1st relief, after completing his task, scrapes his tools and lays 
 them together in rear of the trench. 
 
 The task being completed, each man secures his accoutrements 
 and rifle, and then, under direction of his officers, closes in to the 
 left (or right), forming column of fours which is then marched 
 back to camp. 
 
 As an incentive to rapid work, each relief should be allowed to 
 return to camp on the completion of its task. 
 
 If the w^orking party be large and the work of a complicated 
 nature, each relief should arrive in successive detachments and 
 
WoRKiNd Parties. > "^-(^/l^.- ^<9^ 
 
 their location on the work should have heen previously desrraftted^ ^<V 
 so that there need be no delay or confusion, even at night. ^^O/^. 
 
 Work should not be commenced until the distribution of th^J^/^- 
 entire relief is complete, since any change after work has begun 
 tends to confusion, loss of tools, and delay. 
 
 111. — Tasks. An untrained workman can excavate in ordi- 
 nary soil one cubic yard of earth' per hour for four consecutive 
 hours. As some men work slower than others, however, it is 
 usual to estimate at 6 hours per man for the lifting of 4 cu. yds. 
 of earth from a trench 3.5 to 5 ft. deep and throwing the same a 
 horizontal distance of 10 ft. 
 
 When it is necessary to throw the earth more than 12 ft. hori- 
 zontally, extra shovelers should be provided for re-handling it, in 
 the proportion of 1 shoveler to every 2 diggers. 
 
 When exposed to the enemy's fire, a skirmish line is kept well 
 to the front and the earth first excavated is thrown close to the 
 edge of the ditch, forming a screen which is gradually thickened ; 
 under other circumstances the earth first excavated is thrown 
 farthest. 
 
 Five feet, or two paces, is the usual distance apart for men to 
 work, but they may be posted as close together as 4 ft., while using 
 the heavy pick and shovel. As a precaution against injury to ad- 
 jacent workers, the men should swing the pick in a direction per- 
 pendicular to the tape. 
 
 112. — Working parties may be extended at less or greater in- 
 tervals by making the corresponding changes in the commands : 
 wlien this is done, it will usually be necessary to verify intervals. 
 
 When necessary to complete a task in the shortest possible time 
 or when the men available greatly exceed the number of tools, 
 working parties should be formed in double rank, two men being 
 assigned to each set of tools, which should be carried by the front 
 rank man. When working in this manner with a double relief, 
 the men, under direction of non-commiesioned officers, should 
 change off every 10 or 15 minutes. 
 
 Officers having general supervision of the work should not be 
 changed at the same time the reliefs are. 
 
 The sizes of tasks based on the 4 yd. rule may be arranged as 
 shown in diagram. (Fig. 4.) For arrangement of tasks in diffi 
 cult soil see PI. 14. 
 
CHAPTER IX.— He vet ting Materials and 
 Revetments. 
 
 1 1.*3, A IJevc'tiiu'iit is a facintr used to hold up an enibank- 
 ment at a steeper slope than it would assume naturally. 
 
 114. — Revetting Materials. The revetments most com- 
 monly used in field engineering are made either of brushwood 
 in the rough, fascines, gabions, hurdles, planks, timber, sods, sand- 
 bags, pisa, adobe, or of a combination of two or more of these. 
 
 115. — Briisliwood, which is used in making the first four 
 should be of willow, birch, ash, hickory, or hazel, and is most pli- 
 ant when not in leaf : it may be of any size when used in the 
 rough, but should not exceed an inch in butt diameter for gabions 
 and hurdles and 2.5 in. for fascines and pickets. 
 
 The working party cuts and binds the brushwood in bundles of 
 about 40 lbs. caili. putting the large and small in separate piles 
 with butts in the same direction. For convenience, the detail 
 should be divided into three parts — one for cutting, one for sort- 
 ing and binding, the other for carrying and, if necessary, loading. 
 Tools required and time necessary are as in "Clearing the Ground" 
 (Chap. V). 
 
 116. — Witlies (PI. 17, Fig. 1). which are used for binding and 
 sewing, are made by twisting a pliant rod. The butt is held under 
 the left loot and tlie twisting commenced at the small end, care 
 being taken to avcnd breaking or kinking the rod. The pliancy of 
 the rod may be increased by heating it. In using the withes for 
 binding, an eye is made at the small end, then the withe is passed 
 round the bundle, the butt passed through the eye and twisted 
 until a kink is formed, when the butt is thrust (buried) in the 
 bundle. 
 
 117. — Fascines. A fascine is a bundle of rods tightly bound 
 together. It has a length of 18 ft., a diameter of 9 in., and weighs 
 about 140 lbs. 
 
PLATE 17 
 
 . np.8. 
 
Revetting Materials and Revetments. 77 
 
 Fascine Rack. — The fascine is made in a cradle rack of five 
 equidistant trestles (Figs. 2 and 4), the outer ones being 16 ft. 
 apart, the crotches are each 2.5 ft. above the ground and aligned. The 
 stakes for the trestles should be from 2.5 to 4 in. in diameter and 
 from 5 to 6 ft. in length. Those for the outer trestles are first 
 driven and securely bound together with wire or rope, then a line 
 is stretched from crotch to crotch and the interior trestles made 
 in a similar manner : the stakes should be driven firmly into the 
 ground and each should have a length of 2 ft. above the crotch. 
 
 Fascine Clioker. — For the purpose of gauging the circum- 
 ference of the fascine and for cramping it in binding, the fascine 
 choker (Fig. 3) is used. It consists of two stout bars or hand- 
 spikes, 4 ft. long, to each of which is attached a collar 18 in. from 
 the end, the collars being connected by a stout chain, to which 
 are attached two gauge links 28 in. apart. The choker is used by 
 a man on each side of the rack taking a bar of it and resting the 
 short end on top of the fascine, chain being underneath (Fig. 4, 
 "a"); then each passes his bar over to the other (the short ends 
 passing around and under the fascine), and each bears down on 
 the end of his lever. (Fig. 4, "b.") 
 
 Making" tlie Fascine. — The trestles having been prepared, 
 the fascine is made by laying brushwood, trimmed if practicable, 
 in them, the pieces breaking joints and crooked ones being partly 
 sawed or cut through. The rods should extend from 18 in. to 2 ft. 
 beyond the extreme trestles and the bunch made of uniform size 
 throughout. (Fig. 4.) 
 
 The choker should be used occasionally for testing the size and 
 when of such dimensions throughout that the gauge rings meet, the 
 fascine is bound. This should be done with wire or tarred rope, 
 which is passed twice round the fascine and securely fastened, the 
 bindings being 12 in number, the two outer ones 3 in. outside the 
 extreme trestles and the others at intervals of about a foot and a 
 half. This allows the fascine to be cut into lengths of 6 or of 9 
 ft. Five men require about an hour to make a fascine. 
 
 118. — Gabions. Gabions are open cylinders 2 ft. in exterior 
 diameter by 2 ft. 9 in. in height, varying in weight from 35 to 50 
 lbs.: they are made of bj'uslnrood, ntvap iron, iron hands or sheet 
 iron and from 9 to 14 pickets each. The interlaced brushwood in 
 gal)ions is called the watling or web. Gabion pickets should be 
 3.5 ft. in length and from an inch to an inch and a half in diame- 
 
78 Revetting Materials and Revetments. 
 
 ter. The rods for the'web should be from one-lialf to three-fourths 
 of an inch in diameter, although smaller may be lased. Wicker 
 gabions are most easily made with the aid of a gabion form, which 
 is a circular piece of board 21 in. in diameter, with equidistant 
 notches on its circumference, the number of notches depending 
 on the size of the brushwood and running from 9 to 14. (Fig. 5.) 
 The construction of the Wicker Gabion (Fig. 7) is as follows : 
 Wailing. The gabion form is laid on level ground and a 
 picket driven vertically in each notch, the thick and thin ends 
 of the pickets alternating. The form is thenslijjped up the pickets 
 about a foot and held firmly in place by means of a rope which is 
 tied l(K>sely round the jiickets just below the form and then tight- 
 ened by a rack stick (Fig. 6), the rope holding the pickets firmly 
 in the notches. The rods for the web having been stripped of 
 their leaves, the web is commenced by laying the butts of two rods 
 in adjacent spaces between pickets, resting on the form. The rear 
 rod, passing outside the second picket, is then bent inward, pass- 
 ing over the first rod, inside the third picket, and then out. (Fig. 
 T). ) The other rod, which is now the rear one, is similarly treated 
 and the watling continued by using the rods alternately. This 
 method of watling is called pairing. On coming to the end of a 
 rod a fresh one is laid alongside and woven with it for a short dis- 
 tance. The web is continued to within 3 in. of the ends of the 
 pickets, care being taken to keep the pickets vertical and to make 
 the web close by frequent use of the mallet. 
 
 Sewing*. To prevent the web from coming off the pickets it is 
 then sewed with wire, heavy twine, or withes, in four places, as 
 follows: Take an end of a withe in each hand, the middle of it 
 resting on the web, pass the ends of it through the wel^ about 6 
 in. down the sides, one from without inw aid and the other from 
 within outward ; pull taut by bearing downward. Pass the ends 
 through the web again G in. farther down and tighten as before. 
 Proceed in the same manner a third time and then bury the ends 
 of the withe in the web. The sewing should be at equal inter- 
 vals and the two ends of the withe, when pushed through the 
 web, should be separated by two or three of the watling rods; 
 wire is much easier worked and more durable than withes. The 
 partly completed gabion is now inverted, the form removed, and 
 the watling continued as before, until the gabion has a height 
 of 2 ft. 9 in., when it is completed by again sewing as before ex- 
 
Revetting Materials and Revetments. 79 
 
 plained. The ends of the pickets that were driven into the 
 ground are now trimmed to within 3 in. of the web and sharp- 
 ened, the opposite ends sawed off to within an inch of the web, 
 and a carrying picket driven through the sides of the gabion per- 
 pendicular to the axis and a few inches from it. 
 
 Three men should make a gabion in an hour. 
 
 119. — Wicker Gabion Witlioiit tlie Gabion Form. 
 Where the form is not at hand the wicker gabion is made by 
 first describing on the ground a circle with a 10.5 in. radius and 
 then driving the pickets at equidistant intervals on this line. 
 The watling is commenced at the ground and run up to the full 
 height, care being taken by frequent gauging to keep the dimen- 
 sions accurate. It will be necessary for one man to devote his 
 entire attention to keeping the pickets in position, while a second 
 makes the web, and a third prepares the rods. Three men should 
 make a gabion, without the form, in an hour and a half to two 
 hours. Instead of sewing, the gabion may be finished by driving 
 four forked pickets (Fig. 8) in the web alongside of the gabion 
 pickets. 
 
 120. — Tlie Hoop or Straj^ Iron Gabion. This is more 
 durable and more quickly made than the wicker gabion, but is 
 heavy, weighing 55 lbs., and liable to splinter dangerously. The 
 form for this gabion is used solely for gauging and shaping the 
 bands. 
 
 To make tlie liooi^s, describe on a wooden platform a cir- 
 cle with a 1 ft. radius and divide it into 6 equal parts. Make 
 auger holes at points of division and insert in them wooden pins 
 about 5 in. long and triangular in cross section, the bases of the 
 triangles being on the interior of the circle. (Fig. 9.) Wrap the 
 strap iron once tightly round the pins, thus forming an hexagonal 
 hoop. Mark the point where the hoop is to be joined, then re- 
 move, punch, and rivet it. As the iron is usually 1 in. wide the 
 completed gabion will require 33 of these hoops. 
 
 To make tlie gabion, place a hoop on the ground and an- 
 other on it in the positions shown. (Fig. 10.) Drive a picket 
 vertically in each of the triangular spaces, then place the remain- 
 ing hoops alternately over the first and second. Drive nails in 
 four of the pickets outside the extreme hoops to keep the gabion 
 intact. 
 
80 Revetting Materials and Revetments. 
 
 1 21 .— Tlie Sheet Iron Gabion. This gabion is made of a 
 piece of sheet iron 2 ft. 9 in. x G ft. 4 in., riveted or wired together 
 along its shorter edges. 
 
 122.— Hurdles. The hurdle is a brushwood mat 2 ft. 9 in. 
 wide by 6 ft. long, the length corresponding very nearly to the cir- 
 cumference of the gabion. An even number of pickets, usually 
 10, is used in making it, the extreme pickets being somewhat 
 heavier than the interior ones. (Fig. 11.) 
 
 Construction of Hurdles. Describe on the ground an arc 
 with an 8 ft. radius, measure off 6 ft. of this arc and drive 10 
 gabion pickets along it at intervals of 8 in. (Fig. 11.) Commence 
 the watlftig in the center space on the ground by randing, i. e. 
 working with a single rod alternately inside and outside of the 
 pickets ; on reaching the end picket the rod should be twisted as 
 a withe, so as to avoid breaking it, and then returned toward the 
 center in the same manner as at tirst. When approaching the 
 end of a rod another should be laid alongside of and randed with 
 it for a distance of two or three pickets. Pairing, as in gabions, 
 should be resorted to in finishing the top and bottom of the web 
 and the hurdle should then be sewed as described for the gabion. 
 When the rods used in watling are very small the process of slew- 
 ing should be resorted to: this is the same as randing with the 
 exception that 2 or 3 rods are laid alongside each other instead of 
 using them singly. Slewing makes weaker work than randing. 
 Three men should make a hurdle in two hours; two work at the 
 w^eb and the third prepares the rods. The completed hurdle 
 weighs about 50 lbs. The hurdle is made on a curve and after- 
 ward flattened as much as possible, because it is found that by 
 so doing it is less liable to warp than if made flat. It should be 
 I^laced in a road or revetment with the concave side toward 
 the earth. 
 
 123. — Tlie C\)iitiniioiis Hurdle is usually preferred for 
 revetting jjurposes to single ones joined. It differs from the 
 latter in that the pickets are driven at once, at intervals of 12 to 
 18 in. according to their thickness, in the position the revetment 
 is to occupy, but at a slightly gentler slope so as to allow for 
 straightening when the earth is tamped. It is constructed by 
 randing or slewing, two men being assigned a task of 10 or 12 ft. 
 in length, which they should finish to a height of 4 ft. and anchor, 
 in from one-half to three-quarters of an hour. 
 
PLATE 18. 
 
 Revetments. 
 
 I liii 
 
 ,j ^^fh^mf^%w^^'mWMw--^n^^i 
 
Revettinc; Materials and Revetments. 83 
 
 124. — Planks when used for revetting should be placed 
 edgewise and held in position by stout stakes which should be 
 anchored. They make a neat, durable and quickly made revet- 
 ment. 
 
 125. — Roiiiid timber from 3 to 8 in. in diameter may be 
 used in the same manner as planks but the revetment is more 
 difficult of construction and is not so durable. 
 
 126.— Sod for revetting purposes is cut of a uniform size — 18 
 in. long, 9 in. wide, and 4 in. thick. They should be laid in alter- 
 nate rows of headers and stretchers, grass down, breaking joints, 
 and perpendicular to the slope. The top layer should be all head- 
 ers and have the grass up; alternate rows should be pinned 
 securely, using split pickets, if possible, as with them there is less 
 liability of splitting the sod than when round ones are used. 
 Two men should lay from 70 to 100 sods per hour, depending 
 upon whether or not pickets are used. 
 
 127. — Sand-bags are made of coarse canvas or bagging 
 material and, when empty, measure 2 ft. 8 in. by 1 ft. 4 in. When 
 tilled they are supposed to contain 1 cubic ft. of earth ; it is found 
 in practice, however, that a cubic yard will fill from 48 to 50, 
 making their average size 1 ft. 6 in. long, 10 in. wide, and 
 6 in. thick. Each bag has eyelet holes near the mouth through 
 which a stout cord passes, to expedite tying, when filled. 
 
 For filling sand-bags the working party is divided into squads 
 of 6 : 2 with shovels, 1 with a pick, 1 to hold the bag, and 2 to tie. 
 
 Each squad fills 150 bags per hour. This task may be consid- 
 erably increased, however, in easy soil or with trained men, and 
 the rapidity of the work more than doubled by having a double 
 relief and keeping the men constantly changing. 
 
 128. — Revetments. Brushwood Revetment is made 
 by driving pickets at intervals of about 12 in. along the foot of 
 the proposed slope. The top of the pickets when driven should 
 be as high as the proposed revetment, and the pickets should be 
 anchored by wire to logs or stout stakes in the parapet. Loose 
 brushwood is laid closely behind the stakes and earth tamped 
 against it, the construction of the parapet going on at the same 
 time- 
 Brushwood revetment is rapidly made in daylight but is neither 
 durable nor sightly. 
 
 129.- Tlie Fascine Revetment. (PL 18, Fig. 1.) This is 
 
H4 I V i ;\ KTTl N( . MATKlil A LS AiN 1) KkVKTMKiNTS. 
 
 lujulc l)\ la\ iii<j^ the fascines in single rows of stretchers, breaking 
 joints, each fascine being x^inned to the parapet by 5 or 6 pickets, 
 and every second or third row securely anchored. 
 
 Six-foot fascines should be used occasionally as headers. The 
 bottom fascine is sunk about one-third of its diameter by excavat- 
 ing a shallow trench. The construction of parapet and revetment 
 proceed simultaneously. Slope should not be greater than four 
 on one. The defects of this revetment are the weight of the 
 facines, the large quantity of brushwood required, and llic fact 
 that the fascines are held in place by anchors and pickets in the 
 earth which they support. 
 
 130. Tlie Gabion Ilevetmeiit. (Fig. 2.) This is made 
 by first sinking a row of fascines about 3 in. at the foot of the 
 elope, so as to give an inclination of four on one to the gabions 
 resting i^artially on them. Earth is tamped behind and in tha 
 gabions, and sod or sand-bags placed on top. Where greater 
 height is required two rows of gabions may be used with two 
 facines, well picketed, between them. 
 
 Gabions make one of the strongest and most durable revet- 
 iiKMits. 11i( ii- own weight when filled being usually sufficient to 
 I'l^tain t Ih' einl)ankment. 
 
 MM, I 111 relies. These make a poor revetment unless the 
 method is followed of constructing a ^^continuoitH hurdle'' at the 
 same time with the parapet. To do this, the pickets are driven 
 along the foot of the slope at an inclination of about three on 
 one, when the final slope is to be four on one. The watling is 
 made continuous by randing or slewing, each two men having 
 four paces of hurdle as a task, and taking care to work in their 
 rods with those of adjacent sections. (Fig. 3.) 
 
 132.— Plank or Timber Revetment. (Fig. 4.) This is 
 made by driving heavy stakes into the ground at the proper angle, 
 placing the planks or timbers behind them, then filling in and 
 tamping firmly. The stakes must be anchored. This revetment 
 is neat and durable. 
 
 133."Sod llevetmcnt. (Fig. 5.) This is made by laying 
 the sod in alternate layers of headers and stretchers, grassy side 
 down, breaking joints and perpendicular to the face of the revet- 
 ment. Each sod should be well settled before another is placed 
 on it and the top layer should be headers w^ith grass up. It is 
 well to pin alternate rows by means of split pickets, three 
 
Revetting Materials AND Revetments. I ^'^^r 
 
 lourths of an inch in diameter and 9 in. long. This revetme^ 
 made of uniform thickness throughout by using double rows^ 
 stretchers. If the grass is long it should be mowed. If the sod 
 is very wet when laid the revetment will crack in drying. Two 
 men well supplied with sod should lay two paces of revetment, four 
 and one-third feet high, in an hour. 
 
 This revetment has the advantage of not splintering like 
 gabions, fascines and boards, but should not be used when other 
 material is obtainable because ordinarily it will not stand long at 
 a steep slope (three on one being about the limit), cannot be used 
 when very dry or frozen, and requires great care to build prop- 
 erly. 
 
 134.— Saiid-bag Revetment. (Fig. 6.) This is made by 
 laying alternate rows of headers and stretchers, breaking joints, 
 and perpendicular to slope, seams of stretchers and chokes of 
 headers being put in the embankment. Men working in pairs 
 lay the bags, settling them firmly in place with a mallet or spade. 
 This revetment is not very durable but the bags are easily trans- 
 ported, may be used with any soil, and are invaluable in making 
 hasty repairs and loop-holes. 
 
 135. — A very durable revetment, (Fig. 7,) much used in the 
 defences of Washington 1861-5, was made of posts (oak, chestnut, 
 or cedar) cut in lengths of 5.5 ft. and placed side by side, at a 
 slope of six on one. The footing was a 2 in. plank laid in a trench 
 excavated for the purpose. The tops of the posts were sawed off 
 16 in. below the inferior crest and capped by a half-round timber, 
 all being securely anchored in the parapet. Crowning was com- 
 pleted to the requisite height with sod. 
 
 All revetments that are liable to splinter should be crowned to 
 a height of at least 8 in. with sods, sand-bags or earth. 
 
 136. — Pisa Revetment is made of earth and clay, to which 
 has been added enough water to reduce the mixture to a working 
 consistency. A trench 6 in. deep and 18 in. wide, is first dug, its 
 nearest edge marking the foot of the revetment. Pickets, of 
 sufficient length to reach the top of the proposed revetment, are 
 firmly driven, at the proper angle, about 2 in. from the near edge 
 of the trench, at intervals of about a yard, and then anchored. 
 Boards placed horizontally are now laid against the pickets on 
 the trench side. The trench is then filled with the mixture, 
 tamped, and more added, other boards being placed on top of the 
 
8(5 
 
 Revetting Matekials and Revetments. 
 
 first, as required, and the mixture forced closely against them 
 The construction of the parapet goes on at the same time with 
 the revetment. When completed, the pickets and boards are 
 removed, This revetment is neat and durable but cannot be 
 rapidly made. 
 
 137. — Tlie Adobe is a sun-dried brick, about 18 in. x 9 in. x 
 4.5 in. and when carefully laid with the same bond as given for 
 sod or sand-bag, forms a neat and very durable revetment, exceed- 
 ing in the latter respect any of the other varieties mentioned. 
 
 The following table shows amount of various materials required 
 for 100 running ft. of 4 ft. 4 in. high revetment. 
 
 Kind of Revetment 
 
 Fascines 
 
 Gabions 
 
 Sod 
 
 Sand- bags 
 
 Pickets 
 
 Facines 
 
 Gabion 
 
 Sod 
 
 30 
 
 G 
 
 50 
 
 26t" 
 400 
 1867 
 
 867 
 
 150 
 
 1000 
 
 Sand-bag 
 
PLATK 19. 
 
 Field Casemates. 
 
ClIAPTKK X.— Field Casemates and Ma^^aziiies. 
 
 138. — In all field works, protection against both weather and 
 hostile fire must be provided for the garrison. 
 
 These shelters are constructed by building a chamber of wood 
 sufficiently strong to bear the necessary earth covering, and by 
 protecting this in front by an embankment thick enough to with- 
 stand direct artillery fire. 
 
 Two general forms are used : — 
 
 (1) Those which, after providing complete protection from di- 
 rect fire, have their roofs sloped to the rear at an angle greater 
 than the angle of descent of the enemy's projectiles, generally 
 about one on four ; and, 
 
 (2) Those which have horizontal roofs, the earth covering being 
 so high and massive as to protect against artillery fire by its thick- 
 ness alone. 
 
 The first class is preferable, the work of construction being 
 very much less than in the second class, as the embankment is 
 not so high and the earth on the roof does not require to be 
 thicker than 16 in., as it has to resist only the dropping fire of 
 small arms and the fragments from bursting shrapnel. More- 
 over, it gives much easier drainage to the ditch in rear. 
 
 139. — The construction of the timber part of the casemate is 
 practically the same in both cases. The vertical timbers being 
 rough tree trunks, about 1 ft. in diameter, placed at intervals of 
 3 or 1 ft., and strutted when necessary. The roof timbers in sim- 
 ple casemates being not less than 8 in. in diameter and the inter- 
 stices filled with small poles or brush. In case the protection has 
 to be proof against vertical fire of mortars, the earth mask on the 
 roof must be 6 ft. in thickness and a correspondingly stronger 
 timber construction must be provided : these are shown in PL 19, 
 Figs. 1 to 7. 
 
W Field Casemates and Macjazines. 
 
 In calculating floor space, each man should have from 9 to 18 
 sq. ft.; the former when crowded, the latter when not. 
 
 140. — Ma<^aziiies are of two kinds : Fh^st, those intended to 
 hold the temporary supply for guns or troops when in action; 
 and, Second, those intended for the purpose of storing ammuni- 
 tion in large quantities. 
 
 The first variety consists of recesses in the interior slope of the 
 epaulement — barrels or gabions are excellent and when not ob- 
 tainable may be replaced by empty ammunition boxes placed in 
 holes excavated for their reception. 
 
 Magazines of the second class are used only in w^orks of great 
 defensive value and then only when ample time is available. 
 They are made in the same general manner as the casemates 
 heretofore described, except that great care must be taken to 
 render the structure as dry as possible and to secure good venti- 
 lation. 
 
 141. — The general plan of execution of these works is as 
 follows :— 
 
 (1) Magazine shown in PI. 20, Fig. 1. 
 
 The mask in front should be 20 ft. thick. The roof consists of 
 a row of timbers or logs 8 in. in diameter, overlaid with steel rails, 
 and then covered with a paulin, well tarred if possible. On this 
 is placed IG to 18 in. of earth. The ends are made of logs, 12 in. 
 in diameter, planted in a double row, breaking joints. The en- 
 trance is at either one or both ends according to circumstances. 
 The doors, 2 ft. 6 in. in width, are made of planks crossed, and are 
 hung next to the front wall of trench, opening into a passage 
 formed by a row of upright logs parallel to those on the end of 
 the magazine. At the end of the passage farthest from the first 
 door a second one is hung, opening into the magazine. The 
 vertical timbers in front and rear of trench support a revetment 
 of planks or hurdles. The floor should be raised at least 6 in. 
 from the bottom of the trench, to guard against dampness. 
 Care should be taken to facilitate the draining of all water that 
 falls on the roof, and that the trench itself is drained away from 
 the ends of the magazine. 
 
 142. — Another form is as follows : — Determine the space 
 needed for storage of ammunition. Then build the timber work 
 as in the preceding, first excavating to a depth of 4 or 5 ft. over 
 the entire site. There will be no ends to be closed by timbers. 
 
PLATE 20. 
 
 Maprazine behind naranet. 
 
 Tu/o Storlecl Block IIouso. 
 
 Caponier tn front ofwalL 
 
Field Casemates and Magazines. 93 
 
 The roof is made of timbers 12 in. in diameter, well supported by 
 uprights of same size and long enough to give sufficient head 
 room. The sides and ends should be revetted with plank, if pos- 
 sible, and the floor raised 6 in. above the earth. The center of 
 the roof is raised a foot above the sides and surmounted by a 
 layer of 6 in. of earth, well tamped ; over this is laid a paulin and 
 the earth mask is then placed over all to the thickness of 8 ft.; 
 the covering mass in front should not be less than 20 ft. in thick- 
 ness. Entrance is gained by means of a doorway opening into a 
 passage which communicates through a return with the interior 
 of the magazine. Doors made of crossed planks are hung as in- 
 dicated in the plan. If time is available, and the planks at hand, 
 an interior chamber should be formed, leaving an air space 
 around the magazine proper ; and inlets may be constructed, care 
 being taken that they are not situated in e:^posed positions and 
 that their course is such as to prevent the entrance of sparks. 
 The roof should be rounded off so as to afford the easiest drain- 
 age. If the earth excavated is not sufficient to cover the roof, the 
 necessary amount may be taken from a trench dug around the 
 outside. 
 
 This form of magazine may with advantage be placed in a 
 traverse. 
 
 143. — 111 case timber is not at liaiid, gabions and fas- 
 cines may be used to build the magazine in the manner shown in 
 PI. 20. 
 
 144. — Block Houses are defensible shelters for infantry, 
 although, under certain circumstances, they contain artillery. 
 
 They are generally used for the purpose of flanking defenses 
 whose fire cannot reach into the ditch. 
 
 They are constructed either of upright timbers set in the 
 ground close together, or horizontal timbers laid one upon the 
 other; the timbers being in two rows, breaking joints in each 
 case, or, if both methods are used, the outside row should be hori- 
 zontal and the inner vertical. They should have at least 6 ft. of 
 head room and should not be less than 9 ft. wide, as this allows 
 one row of beds only. The roof should be of solid construction 
 and covered with earth to the thickness of 2 ft. and should pro- 
 ject 2 ft. over the wall to protect from dropping fire. 
 
 The walls should be masked with earth as high as possible and 
 a ditch dug around the entire building. Loop holes are made at 
 
94 Field Casemates and Magazines. 
 
 the height of 4 ft. 4 in. and are cut according to circumstances, 
 as described in Chap. XIII. If necessary, block houses may be 
 sunk in the ground, but a limit of 4 ft. in depth should be ob- 
 served. The shape will conform to the necessities of the case. 
 
 145. — 111 isolated positions they are advantageously made 
 cruciform, thus presenting an opportunity for flanking each face 
 of the house. When in wooded and mountainous countries, 
 where artillery is not to be feared, these houses may be made 
 with two stories, built so that the angles of the upper story pro- 
 ject over the sides of the other, forming a machicoulis gallery, 
 thus preventing the occupation by the enemy of the dead space 
 in front of the straight walls. 
 
 146. — Cajioiiiers are sunken block houses placed in the 
 ditch of fortified places to prevent their occupation by the enemy: 
 they are loop-holed about 18 in. from the ground, so as to have the 
 most effective plane of fire. (PI. 20.) 
 
 147.— Tambours are essentially block houses, having for 
 their object the protection of angles, and the flanking of sides of 
 buildings, and are especially useful in defending doors of build- 
 ings. 
 
CHAPTER XI.— Field Works in Combination. 
 
 148. — Where several field works are used in conjunction, 
 either as an intrenched position or in the investment of a fortress, 
 city, or other important point, they constitute what is known as a 
 Line of Woy^ks. 
 
 A liine of Works may be continuous, that is, forming, 
 together with natural obstacles, an unbroken line, or, with inter- 
 vals, by which it is understood that the works are distinct, 
 either suijporting each other or not, and the spaces between 
 them not impassable by reason of natural obstacles. 
 
 149. — Ijines witli intervals have the following advantages 
 over continuous lines, viz: — 
 
 (a) They involve less labor. 
 
 (b) The garrison of the defenders may be smaller. 
 
 (c) They allow greater freedom of movement for counter attacks. 
 
 The general principle to be followed in their construction con- 
 sists in forming a line of fortified points or pivots. These points 
 or pivots detain the enemy's advance, since he would hardly pass 
 them and expose his flanks and rear, while a continued unsuc- 
 cessful attack on the strongly fortified pivots would open the way 
 for a counter attack by the defenders. 
 
 When, however, the defense is intended to be solely passive, 
 which would be the case while awaiting reinforcements, or when 
 the enemy greatly outnumbers the defenders, the intervals would 
 be obstructed by felling trees or using any available obstacles, 
 since counter attack is not contemplated. 
 
 In the use of lines with intervals, if the general defensive line 
 is straight the w^orks could be blunted lunettes with flanks traced 
 so as to protect the front of adjacent works. If on a convex 
 curve, 'the capitals should radiate from a common center, while 
 
l>0 Field Works in Combination. 
 
 on a curve concave toward the enemy, the capitals should con- 
 verge and the front of each work might be a straight line. 
 
 When impracticable to construct the main works of a line with 
 intervals, within supporting distance (600 yds. for infantry and 
 2000 yds. for artillery)* of each other, intermediate works retired 
 from the main line, not more than half the interval, may be 
 used. 
 
 In PI. 21, Fig. 6. is shown such an arrangement, the pivots 
 being single works while the artillery is retired from the main 
 line and supported by infantry in shelter trenches. 
 
 Where the interval is as great as 1,500 yds. it is advisable to 
 strengthen the pivots considerably, forming groups, the individ- 
 ual works of each group being so traced as to afford mutual 
 defense. ( PI. 15, Fig. 2.) Each group in this latter arrangement 
 forms a strongly fortified point of support and would usually have 
 suflScient strength in itself to resist assault. 
 
 150. — Sometimes, when the defense of a line is of vital impor- 
 tance to the defenders, a douhlr line of trorks is employed, the 
 front line being shelter trenches or open field works of slii!:ht 
 profile, the second line, not over 500 yds. in rear of the first, ])eing 
 field works of strong profile. 
 
 151. — Artillery should, as a rule, be placed outside of and 
 somewhat retired from the works and protected by their own gun- 
 pits or epaulements, for the reasons — 
 
 (1) That the works gain much in simplicity and rapidity of 
 construction. 
 
 (2) That this disposition drawls the enemy's artillery fire from 
 the works and renders it more scattering. 
 
 (3) Greater mobility is given to the defender's artillery in case 
 of advance or retreat. 
 
 (4) A better tactical position for this arm can often be secured 
 than the one selected for infantry. 
 
 152. — As examples of continuous lines, PI. 21, Fig. 1. is known 
 as the redan trace with curtains. Fig. 2. is a modification of 
 Fig. 1., the redans being blunted. Fig. 3. is the tenaille trace. 
 Fig. 4. is a tenaille and redan trace. The cremaillere trace (Fig. 5) 
 has long faces and short flanks. 
 
 With respect to the continuous lines above mentioned, the 
 
 * Continuous dangerous spac© for new Infantry rifle (Krag-Jorgenson) is 610 yards. 
 
PLATE 21. 
 
 PIG.l. 
 i30 to 600 mtxif /^toeoy,^,^^ 
 
 FIG.2, 
 
 FIG.5. 
 
 , ^ 6WtoiZ00<^rds 
 
 FIG.6. 
 
 
 •^^^^^ 
 
 Ji^ilitary Ovst 
 FIG. 7 : 6 
 
Field Wokks in Comiunatjon. 99 
 
 preference on a level site would usually be given to the trace 
 shown in Figs. 1 and 2, the artillery being placed in the most 
 favorable position along the curtains, with machine guns in the 
 most important redans. 
 
 The tenaille and the tenaille and redan trace (Figs. 3 and i.) 
 are objectionable, in that they involve more labor, cannot bring 
 as direct a fire to the front, and the faces are liable to enfilade 
 when the salient angles approach 90°, while, on the other hand, 
 if a salient, as "S," Fig. 4, approaches 120°, mutual defense of 
 the faces, "f and"g," would be lacking, thus making the re- 
 dan, " R,'- necessary. This trace may, however, be rendered un- 
 avoidable by the conformation of the ground. 
 
 The cremaillere trace finds special application in a position such 
 as is indicated in Fig. 5, viz., joining two points, one at the top 
 and the other at the bottom of a slope, the short flanks affording 
 but limited opportunity for enfilade fire. 
 
 153. — Tlie streiigtii of a defensive xiositioii lies in a 
 great measure in the proper utilization of the accidents of 
 the ground; thus, the traces that have been mentioned may 
 have to undergo considerable modification to be appropriate to 
 the varieties of terrain constantly met. It is evident that, 
 in a broken or hilly country, one by preference would occupy 
 the heights. These, from a tactical point of view, possess 
 the advantage of overlooking the low ground in front, besides the 
 great advantage of concealing from the enemy the movements of 
 our own troops in rear ; but, since all else must be subordinated 
 to fire effect, it is evident that such a line on the heights should 
 be selected that the defenders may completely cover the ground 
 over which the enemy must approach. This naturally leads to the 
 inquiry as to how that line may be determined. 
 
 Heiglits, great or small, usually present the profile shown in 
 in Fig. 7, that is to say, they have a steepest slope, " b c," which 
 is joined to the crest and to the valley below by the two gentler 
 slopes, "a b" and "c d.'' In order, then, to beat the zone "b c'' 
 it is necessary to occupy the crest " c " or some point below it on 
 this slope. To distinguish this crest from others, it will be called 
 the military crest. 
 
 With the inclination of this steepest slope greater than one on 
 four, it is unusual to construct anything but shelter trenches 
 along the military crest, the artillery being retired sufficiently and 
 
MHi Field Works in Combination. 
 
 l)laceil ill Buch positions as to command a good view of the rest of 
 the field. With gentler slopes, however, the artillery may be 
 placed at intervals along the military crest, the intermediate 
 spaces being held by infantry in shelter trenches. 
 
 A better disposition than this, where the ground permits of it, 
 is to place the infantry trenches part way down the slope in front 
 of the military crest, the artillery occupying a position in rear of 
 and close to the crest, so that little more than the muzzles of the 
 pieces are visible. In this case care must be taken that the in- 
 fantry trenches do not mask the fire of the artillery. 
 
 Ill clioosiiijj; a defensive ])ositi()ii the ground should be 
 viewed from the highest point in the vicinity and by frequent 
 practice the eye so trained that the military crest is at once ap- 
 parent and the slopes instinctively classified with respect to their 
 use by the different arms. 
 
 Finally, the distance to a number of visible permanent points 
 in front of the works should be determined and recorded, so that 
 there may be no necessity for range finding during the enemy's 
 advance. 
 

 ^NW." 
 
 Slj.^ 
 
PLATE 22. 
 
 Fig.l 
 
 Fig. 2, 
 
 Fig. 3. 
 
 Fig. 4 
 

 CllAPTKR XII. Siege Works. 
 
 154. When it becomes necessary to besiege a place, it may be 
 approached by common trench work or by some form of sapping. 
 As the common trench and the flying sap are the work of infan- 
 try, they alone will be referred to. 
 
 155. — The method of providing the working party with tools, 
 laying out the work, and extending the working party is described 
 in Chap. VIII. It is to be noted,- however, in work of this char- 
 acter, til (it when extending along a zig-zag, upon reaching the 
 a)igle the order of forming uj) must he reversed. Thus, if the 
 column from b to c (PI. 22, Fig. 1) were forming on the left, upon 
 reaching e f, it would form on the right. 
 
 156. — Conimoii Treiicli Work. This may be used as a 
 ])jirallel, an oblique approach, or communication. The work done 
 by reliefs in constructing a parallel is shown in Fig. 2. In this 
 case, as musketry tire- must be provided for, the second relief cuts 
 out the top step. Should it be necessary to revet the bottom step, 
 fascines for this purpose may be carried by the second and third 
 reliefs. This may be and usually is omitted until the parallel is 
 completed. Fig. 3 shows the common trench used as an oblique 
 approach or communication. Should the trench be found wide 
 enough the task of the third relief may be omitted. 
 
 157.— Tlie Flying Sap (Fig. 4) is similar to common trench 
 work, except that in the former case the embankment is revetted 
 with gabions. 
 
 In taking tools, each man of the first relief is, in addition to his 
 pick and shovel, provided with two gabions. In laying out the 
 tools, a shovel should be fastened in one gabion by being placed 
 between two of the gabion pickets, handle of the shovel inside. 
 A pick should be secured in the other gabion by having its point 
 pushed under the pairing rods, handle inside. The gabion with 
 
104 
 
 SlKCK Wc.KKS 
 
 sliovcl is tjikcn in ihv v\<^h\ liand. the one with ])ic'k in the left: 
 ))(»tli .u-;il)i()us hciiii;' caiM-ict] l)y cjin-yiii- pickets. 
 
 15S. The extension in the Mvini: sap is inadr liom 
 Bin,Li"]<' rank on the ri«j;iit or lolt, and ditlVrs i'loiii tin- extrusion in 
 eoinmon treneli work in that the intervaL in the former case, is 
 tlie widtli of two ii-abions. Each man. on eomino^ into line, 
 places his ;^al)ions so that llie\ toucli each other alon,ii- the iimer 
 cdL^'c of the tai)e. takes out his tooLs and hiys them down, as ex- 
 |)hnne(l for workinii' ])arties in C'liap. VIII., and waits for tlie com- 
 mand. "('ommenc<' work." In comnuMK-inu- work, tlie ^'abions 
 siiould fii-st l)e tilled. lienc(^ llie position of each pair of <4-ai)ions 
 s^liould l)e I'cctitied hefoi'c this command is .L;i\('n. 
 
 151). Ivicli l)ranch of a zi.u'za.L;- should recei\-e sucli (hri'ction 
 as not to expose it to entilade tii'c from any ])oint of the defenses. 
 Its })ro]()nLiation sliould. tluM-efore, fall oiitsi(h' of tlie most ad- 
 vanced salient of the c(.llateral works. ()rdinai-il\ it would not 
 he lon.u'cr than UK) yds. A i)arallel should be step])ed in ord(M- to 
 facilitate an a<l\ance from it. 
 
 1()(>. A portion of the ])arallels and a|)proaches used in the 
 eai)ture of t'ort Wanner, Morris Island. S. C, 8epteml)er Tth, 
 IHCx], is shown in Tl. '2'.). 
 
PLATE 23. 
 
9LATE 24. 
 
 Figure 1. 
 
 .3' Figure 10. 
 
 Figure IL 
 
CHAPTER XIII. Defense of T^ocalities. 
 
 161. — Walls. Should the enemy close on them, walls mvist 
 be so prepared that they will neither screen nor cover him, nor 
 permit his firing from them. To prevent this, obstacles may be 
 placed in front, or a ditch may be dug outside which will place 
 him so far below the top of the wall or the bottom of the loop 
 holes that he cannot fire over the one or through the other. A 
 total height of 6 ft. will prevent this, or, in case of loop holes close 
 to the ground, the maximum height should not be greater than 1 
 ft. from the outside, or an embankment made in rear 18 in. high. 
 
 Notwithstanding these precautions, walls may still give cover, 
 hence they should be flanked when possible. 
 
 162.— Ill jirepariiig Avails for defense, the following 
 cases arise : — 
 
 (1) A w^all less than 4 ft. high. Sink a small trench on the in- 
 side to gain additional cover. Fire over the top. (PI. 24, Pig. 1.) 
 Head cover should be provided with logs, sandbags, or sods, sand- 
 l)ags being the best, sods next. 
 
 Additional protection against artillery may be obtained by 
 heaping earth from the ditch in front against the wall, the thick- 
 ness depending on the kind of artillery the wall is to resist. 
 
 If this should be done, the ditch should not be too close to the 
 wall. A trench should be dug in rear to give cover to the sup- 
 ports, or for the firing line when not firing from the wall. 
 
 (2) A wall between 4 and 5 ft. can be used as it stands, subject 
 to the same modifications as in the preceding case. (Fig. 2.) 
 
 (3) Between 5 and G ft. a wall can be notched. The tops of the 
 notches may be filled with sandbags, sods, etc. (Fig. 3.) 
 
 (4) Should the w^all be higher than G ft., a i)latform or staging 
 must be raised inside to enable the men to tire over the wall or 
 through the notches, or else the wall must be loop-holed. 
 
110 Defense of Localities. 
 
 1 03.- -L(00i)-IIoliiig. Loop holes for fire should not be 
 closer than 2 ft. 6 in.; ordinarily they should be 3 ft. To find the 
 height hold the rifle in the position intended to he used. 
 
 164.— To make a loop hole in a wall (Fig. 4), 14 in. or less in 
 thickness, begin on the inside, to prevent the splay being toward 
 the outside, by detaching a stretcher : the adjacent header on the 
 outside can then be knocked out and the loop hole roughly 
 shaped. Outside dimensions, 4 in. wide by 3 in. high. Tnterior 
 dimensions will depend on the nature of the grouml over which 
 fire is to be delivered. For horizontal fire increase the breadth, 
 for elevated or depressed fire increase the height. 
 
 In walls of ordinary thickness, a loop hole can be made in 
 about 15 minutes, a notch in about 5 minutes. 
 
 165. — For a thick wall (Fig. 4), the small part should be at the 
 center, the loop hole splayed to the front and rear, for it will do 
 this anyway. The side toward the enemy may be stepped, in 
 order that bullets striking it may flatten. Loop holes of obst^rva 
 tion should splay towards the outside. 
 
 All loop holes, when not in use, sliould bo blinded. 
 
 166. — Tlie lieiji^lit or position of tlio loop liole is in- 
 fluenced as follows : — 
 
 (1) 1 ft. above the ground. Men lying down in a shallow exca- 
 vation. Earth heaped up to 18 in. in rear prevents the enemy 
 from using the loop holes should he close on the wall. The loop 
 holes are a difficult mark for the enemy and sentries at night can- 
 watch the sky line. Cannot be used where ground in front is 
 broken. 
 
 (2) Loop holes 2 ft. 3 in. Sitting. Position easy, but must have 
 a deep ditch in front. 
 
 (3) Loop holes 3 ft. Kneeling. Position strained and must 
 have a deep ditch in front. 
 
 (4) Loop holes 4 ft. 4 in. Standing. Good command, but easier 
 mark for enemy : ditch necessary, but not so deep as in cases 2 
 or 3. 
 
 (5) Loop holes 6 ft. or more. Men standing on banquette. Best 
 position for view or fire ; no ditch in front ; banquette strengthens 
 wall, but takes longer to prepare wall in this manner ; more sus- 
 ceptible to artillery fire. 
 
 167.^ — In order to allow a double tier of fire, walls should be at 
 least 9 ft. high. (Figs. 5 and 6.) 
 
PLATE 25. 
 
 Figure 1 . 
 
 Figure 2 
 
 Fioure 3 
 
 Figure 6 
 
 \ 
 
 Figure 9. 
 
 Figure 10 
 
Defense of Localities. 113 
 
 108. -Fences. Fences should be removed or left standing 
 according to their jjosition or direction. Wire fence forms a good 
 obstacle, a rail or plank fence forms a screen and may be banked 
 with earth to giv^e cover. If fence is of stone it may be treated as 
 explained for walls. 
 
 169. — Hedges. Almost the same principles as explained for 
 walls apply to hedges. A hedge primarily acts as a screen, but to 
 resist projectiles must be banked up with earth. 
 
 Hedges possess the following advantages : (1) With little labor 
 afford good cover. (2) Serve as a screen and also as a revetment. 
 (3) Act as an obstacle to the enemy. 
 
 To derive these advantages hedges can be treated as follows : — 
 
 (1) A hedge with a ditch on the defenders' side. Can be used 
 as it stands, the ditch being converted into a trench, widened and 
 improved if necessary. (Fig. 7.) 
 
 (2) A hedge with a ditch on the enemy's side. Deepen the 
 ditch, if necessary, and throw the earth to the defenders' side 
 to give cover. If this is not possible, scatter the earth and dig a 
 trench in rear. (Figs. 8 and 9.) 
 
 (3) A hedge with ditches on both sides. Deepen the ditch on 
 the enemy's side, using the earth to obtain cover. Trench on de- 
 fenders' side may be deepened. (Fig. 9.) 
 
 (4) Hedge on sloping ground. Gain cover by a small trench in 
 rear ; scarp away the ground in front, forming a glacis. (Fig. 10.) 
 
 (5) High and strong hedges. When time is available, may be 
 treated as in Fig. 11. This is advantageous where additional com- 
 mand is required. 
 
 (G) A sunken road with hedges on both sides. Dig a shelter 
 trench in rear of the hedge on defenders' side and utilize the 
 earth to form a breastwork. Cut down the hedge on the enemy's 
 side, entangling it to form an obstacle. 
 
 (7) Hedge without ditches. Excavate a shelter trench on de- 
 fenders' side and ])ank up the earth against the hedge as a breast- 
 work. 
 
 Weak j)laces in liedges should be closed up with boughs, stakes, 
 wire, etc., as a strong hedge, in addition to being a screen, forms a 
 very efficient obstacle. 
 
 ITO. — TCnibaiikmeiits may be ddViuled: — 
 
 (1) Narrow Embankments. By occupying the inner edge bet- 
 ter cover is obtained, })ut, unless the bank is both low and narrow, 
 
114 Defense of Localities. 
 
 there is a dead space in front at the foot of the outer slope. (PI. 
 25, Fig. 1.) 
 
 (2) Broad Embankments. By occupying the front edge, a 
 better field of lire is obtained, but less cover can be jjrovided for 
 the firing line, and the sui)])oits aic exposed when coming into 
 action. (Fig. 2.) 
 
 171." Cuttings are usu:ill\ tlctcndcd on the defcndci-s' side, 
 since ill this case retreat is easy and the cutting itself forms an 
 obstacle to the enemy's advance. But for active defense the front 
 edge may be held and then a forward movement is possible. In this 
 case a means of retreat must be jjrovided. 
 
 172. "Fig. 3 shows a case where the fall of the ground admits 
 of botli sides of the cutting being occupied, giving a double tier of 
 tii( . 1 he command of the higher edge over th^ lower should be 
 about G It. 
 
 173. — In case of a road cut, as in Fig. 4, the vipper fence may 
 be used to sustain a breastwork, while the hedge below may be 
 converted into an obstacle. 
 
 174. A\ Oods. (PL 26, Fig. G.) Preparation of odoe of 
 Avood occiii)ied. The edge of a w^ood should be put in a state 
 of defense and an abatis is the readiest means of doing it. The 
 salients should first be prepared, the re-entrants next and then 
 roads entering the wood from the enemy's side. Instead of an 
 abatis, the outer trees may be left standing and an entanglement 
 made by packing in among them smaller trees cut about 10 to 20 
 paces to the rear. This clearing will serve as a communication all 
 round the edge of the wood. 
 
 If a re-entrant bend is deep the abatis or entanglement may be 
 carried straight across it and flanked from the adjacent salients. 
 In case of a road, a lunette may be used instead of the abatis or 
 entanglement. In case there is not time to prepare the entire 
 edge of the wood, the salients may alone be prepared, the flanks 
 of the defense being turned back for a short distance into the 
 wood. 
 
 175. Pre])aratioii of woods lying beyond. Woods 
 beyond, witliin rifle range of the line of defense, but too far to the 
 front to be occupied, and too extended to be felled, should have an 
 abatis or entanglement on the rear side to act as an obstacle. 
 
 176.— Cover. Trench digging is difficult on account of the 
 roots, but when possible it should be done. Cover is generally 
 
PLATE 20. 
 
 Fig. 6 
 
 %v-^ 
 
 
Defense of Localities. 117 
 
 obtained from the natural features. Trees, unless very large and 
 standing thickly, do not give complete protection against artillery 
 tire. Troops as supports and reserves, if not so far to the rear as 
 to preclude their seeing through the wood to the front, may be 
 co\erod by log walls and trenches. 
 
 ITT. ('oiiiiiiiiiiicatioiis. (a) There must be good radial 
 (M)iuiuunication as well as free movement along the boundary in 
 rear of the firing line. 
 
 (1)) Roads and paths for bringing u}) the suiJi)orts must be 
 clearly marked by blazing as well as by posting sentries at all 
 cross roads. 
 
 (c) In dense woods, preparations should be made for blocking 
 up roads by cutting trees on either side of them nearly through, 
 to be pulled down across them in case of retreat. 
 
 1T8. — Second and tliird lines may be placed along any 
 open space, brook, or broad road, parallel to the front. In case of 
 l)r()ok, the brook should be in fron^t of defenders' jjosition. 
 
 1 TO. — Artillery should generally be placed outside of the 
 wood on the tltuiks. 'If placed in the wood, batteries should be 
 })laced far apart, near good roads, masked as much as possible and 
 each gun having more than one position. Re-entrants are desir- 
 able. 
 
 The number of defenders is estimated at 2 to 3 men per yard of 
 front. 
 
 180.— Stockades.' Stockades are timber defenses, made by 
 Ijlacing one or niore rows of timbers or rails, upright or horizon- 
 tally, and so close to one another as to keep out rifle bullets, 
 loop holes being made through which fire is delivered. They 
 have the advantages of combining a parapet and an obstacle in 
 one, giving good cover and ample interior space, and of being 
 easily guarded against surprise. On the other hand, they re- 
 quire considerable time for construction, a certain amount of skilled 
 labor, and are easily destroyed by artillery fire. 
 
 181. — Stockades Avould be enii)loyed: — 
 
 (1) Where timber is plentiful. 
 
 (2) When artillery tire is not to be resisted. 
 
 (3) When acting purely on the defensive. They are useful for 
 the rear faces or gorges of enclosed works, and may be a good deal 
 used in the defense of houses, streets, villages, and even woods. 
 
 182.— Stockades of vertical timbers. Vertical timbers 
 
118 I )i;i'i:nsk ok I^ocalii'i ks. 
 
 sliould Ix' close lo!4Tt li(M\ ])lan1<'(l in \]\v ground to a (l(>])tli of .*> or 
 \ ft.. accoi-diiiLi- to their size and \veii:ht. pointed oi- spiked at the 
 toj). and loo|) holed at intei'vals. A rihand must he s])ik(Ml aloni*' 
 the iusitlc. near the top. to keep the tinihers close toiictlHM". 
 
 I S;5. PI. "J.'). l^')<^s. ."),('). and 7. show stoclvades w ith squared tim- 
 IxM's: l''i,Li'. S wit li round tinihei-s S(iuared wliere they touch and 
 tlie joint hetween every two trees made uood on the inside by 
 a smaller tree. 
 
 I SI. The loop holes should he made in the crack hetween the 
 timbers, in order to asoid weakening" them, half hein^' cut out of 
 each. (FiK- ^•) In round tind)er. two saw cuts will make a looj) 
 hole. (Fi^. 10.) 
 
 185. — The loop holes should be cut before the timbers are 
 ])lac(Hl in jjosition and the same precautions in regard to them as 
 given in walls should be observed. A loop hole can be cut in 
 from 10 to 15 minutes. • 
 
 1 S(). — Tn the foregoing cases, where the stockade is built of 
 timl)ers |)lace(l vert ically, squared tindx^rs are preferred, as they 
 are more easily fastened togethei- and the joints made bullet 
 proof. In round timl)ers the logs sliould be as straight as possi- 
 bl(\ If very erooked, two eom])lete rows will l)e rcMjuired. 
 
 ()n(^ X. C (). and K* men will ertn-t b") running fcM't of stockade 
 of squai-od tind)er. with one tier of loo]) holes, in 8 hours. 
 
 1 ST. Stockados of liori/.oiital tinihers, iron rails, fas- 
 cines, or logs. (PI. 26.) 
 
 Fig. 1 shows stockade of rails and ties. Can only be used for a 
 very short distance as it will involve an immense amount of plant. 
 Can be used to cover guns, close a road, and is more properly 
 a barricade. 
 
 Fig. 2 shows a stockade or log breastwork, banked in rear with 
 earth held in place by planks or hurdles and stakes. 
 
 Fig. 3 shows a stockade or breastwork of logs and fascines. 
 
 1 88. Stockade work, both vertical and horizontal, can be 
 used for the construction of ((onbours (Figs. 4 and 5) and capon- 
 h'i's for flanking walls or stockades and covering entrances. Tam- 
 bours may be triangular or rectangular in shape, arranged for one 
 or two tiers of lire, and covered with a splinter-proof roof. 
 
 1 81).> Biiildiiio's. Buildings may be used for defense, either 
 singly or in cond)ination: 
 
 (a) As tactical jjoints in the l)attletield, held either as advanced 
 
Defense of Localities. 119 
 
 posts or as supporting points in the line, or on the flanks, or as 
 rallying points to cover retreat. 
 
 (b) As keeps to a more extensive position, such as a wood, vil- 
 lage, etc. 
 
 (c) As an isolated post on the lines of communication. 
 
 190. — In order to admit of use as a defensible post, a building 
 should possess the following requisites: — 
 
 (1) Solidly built of soft stone, brick, or adobe. 
 
 (2) Large enough to hold at least half a company. 
 
 (3) Sheltered from distant artillery fire, otherwise the building 
 cannot be held against infantry or cavalry. 
 
 (4) Well selected for the object in view. 
 
 (5) Low, flat roof. 
 
 (6) Clear field of fire obtainable. 
 
 (7) Shape in plan affording flank defense. 
 
 191. — The building should be looked upon as a keep, or second 
 line of defense, a first line being prepared at a minimum dis- 
 tance of 40 yds. to the front, this distance being the least that 
 will give the defenders immunity from splinters caused by shells 
 striking the building. 
 
 192. — 111 falling back, the first line should retreat pasf, not 
 into the house, which should by this time be occupied by the sup- 
 ports. The garrison of the house may be estimated at two men to 
 each door, window, or loop hole, with a reserve of one-fourth, tac- 
 tical unity being in this, as in all similar cases, adhered to as 
 much as possible. 
 
 193. — The following are the steps which must be taken in 
 hastily preparing a house for defense: — 
 
 (a) Remove the inhabitants, also all easily combustible mate- 
 rial, and provide water and heaps of earth in each room. 
 
 (b) Barricade doors and ground-floor windows (bullet proof if 
 possible), also mask inaccessible windows, and remove all glass. 
 
 (c) Make loop holes in doors, shutters and walls, and, in the 
 case of a sloping roof, remove tiles or slates. 
 
 (d) Clear away cover in the vicinity as far as time and means 
 will allow. 
 
 (e) Open up communication throughout and prepare a means of 
 retreat. 
 
 194. — The same precautions as to loop-holing walls apply in 
 case of buildings. On the ground floor the horizontal dimension 
 
1-0 Defense of Localities. 
 
 of a loop hole should be greatest ; on upper floors, the vertical 
 dimension. If an artillery attack is feared, shelter trenches 
 should be provided outside the building on the flanks. 
 
 195. -l$arrieades for Doors may be made in the following 
 wjiys: 
 
 (a) Fill boxes, barrels, cupboards, etc., with earth and i)lace 
 them against the door inside. 
 
 (b) Build a wall of brick, stone, flag-stones, or hearth-stones, 
 against the door inside, and support by a shutter or another door. 
 
 (c) If railway plant is available, pile ties horizontally on one 
 another and secure with telegraph wire. 
 
 (d) Pile lumber inside the door and flx with blocks nailed to 
 the floor. 
 
 (e) Other methods may be employed in accordance with mate- 
 rial available. 
 
 196. — Should a door be reserved for use, it should be in a re- 
 ciitcrinir an^^lr of the building, if possible, and protected from 
 tire. A couple of chests fllled with earth and jjlaced on rollers 
 may be used to secure the door. Similarly it may be possible to 
 place iron or wood on the door, thus rendering it bullet proof. 
 
 197 >\'in(loAvs. Windows must be barricaded as explained 
 for doors. If provided with shutters, these should be utilized. 
 Upper windows require to be bullet proof only high enough to 
 cover the defenders. Bedding is no protection against modern 
 rifles, but may be used to mask windows of upper floors. If tim- 
 ber is used it should be placed vertically and nailed to horizontal 
 ribands strutted back to the floor. 
 
 198. — If the house is large and strong and is to be held to the 
 last, in addition to the foregoing, the following preparations 
 should be made: 
 
 (1) Arrange for storage of provisions and ammunition. 
 
 (2) Set apart a place for a hospital. 
 
 (3) Prepare latrines. 
 
 (4) Loophole partition walls and upper floors. 
 
 (5) Make ready barricades to cover retreat from one part of the 
 building to another. 
 
 (6) If artillery is feared, shore up the floors and cover them 
 with about 3 in. of earth. 
 
 199. — Should the construction of the house not afford suffi- 
 cient flank defense, it can be improvised in the shape of tambours 
 
^ifX 
 
 
PLATE 27 
 
 Fig 2. 
 
 Fig. 6, 
 
 yrrrftflttrfHtttrtttltflrtV 
 
 fmfiTtfmff.,,, , 
 
 . ww\\k \%. ^,: K, s, < 
 
 V \ V "^ V ^ \ X A <». ^' ,^ ^ 
 
 
Defense of Localities. 123 
 
 or caponiers, but the labor involved in their construction is con- 
 siderable and they would only be undertaken for the defense of 
 a very long wall or to cover an important entrance or communi- 
 cation. 
 
 For the latter purpose a macliicouli^ gallery is sometimes em- 
 ployed. (PL 27, Fig. 3.) This is made by removing the wall of 
 the upper story where a window occurs down to the level of the 
 floor, running out two or three long balks so as to project a few 
 feet beyond the wall, the other ends being secured down to the 
 floor. On these planks are nailed, with holes cut through to act 
 as loop holes, and a musket-proof parapet of planking, sand-bags 
 etc., is built all around. A projecting veranda offers a favorable 
 position for this arrangement. 
 
 Second method : If a regular gallery can not be made, holes 
 may be cut in the wall at a convenient height for a man to fire 
 downwards when leaning over, and a screen of wood or other ma- 
 terial may be secured outside for, protection. (Fig. 4.) 
 
 If neither of the foregoing methods be i)OSsible, holes may he 
 made in the roof, through which grenades may be thrown on the 
 enemy. 
 
 200.— The materials most likely to be useful in preparing a 
 house for defense are sand-bags, stout timbers, such as railway 
 ties, large boxes, chests, barrels, coal-boxes, furniture and bed- 
 ding. 
 
 201.— PI. 27, Figs. 1, 2 and 5, illustrate the more important 
 points in the defense of a house. 
 
 202. — Farms. Farms should be defended according to the 
 nature of the surface covering, the ground and the improvements, 
 and may involve the preparation for defense of walls, hedges, cut- 
 tings, embankments, buildings, woods, etc. Owing to their posi- 
 tions, farms may become very important and a great amount of 
 fighting take place for their possession. They may occur either 
 in the main line of a position, as an advanced post in front, or as a 
 reserve station or rallying point in rear. 
 
 203. — Fig. G shows the principles of defense apijlied to a farm 
 lying in advance of a stream, which is a point that requires In he 
 strongly held. From the position of the farm it must be held as 
 an advanced i^ost. 
 
 The firing line is established along the fences bounding the 
 fields and orchard. The farm buildings are loop-holed and can 
 
1-i Dffknst: of Localities. 
 
 Ijc held should the liring line be forced, while the fire from the 
 house would render occui^ation of the farmyard l)y the enemy 
 diffieult. Further to the rear, the wood is strongly prepared foi- a 
 tinal jinsitioii. as shown in the figure. 
 
 LM)I. ^rhc real- (.r an advanced post slionld he left weak and 
 ojicn to facilitate i-ci-aj)tiirc. 
 
 2<)5. \' illa«>;es. Villages can l)e ra])idly ])i-e})arcd for defense 
 and. nndcr favorable circumstances, obstinately defended: conse- 
 (|uently they ai'e va]iial)Ie sujjporting i)oints in a defensive line. 
 Owinu" to the ellVct of modern artillery and tlie ai)ility of l)nrst- 
 in^- shells to set \ illages on fire, great i)i-ecautions Ikinc to he 
 taken in the i)re|)arati()n for defense. 
 
 LM)(>. A Nillau'c. when ])ro]ierly pi-ej)ared and d(>fended, may 
 have the following advantages: 
 
 (a) Can l)e rapitlly placed in condition for delense. 
 
 ())) Defense may be ohstinate thus giving time. 
 
 (c) Conceals the sti-ength of the deh-nders. 
 
 (d) Provides a certain amount of covei- from tire. 
 • (e) Shelter from the eh'ments. 
 
 On the other hand: 
 
 (a) The gaiivison is scattered, hence the difTundty of sujier- 
 \ ision. 
 
 (I)) When under artill(>ry tire. s])linters may cause many casu- 
 alties. 
 
 (c) Liability to be set on hre l)y shells. 
 
 207. — A village may be held with the following objects in 
 view: — 
 
 (a) As a supporting point in the main line of defense. 
 
 (b) As an advanced post in front of the main line. 
 
 (c) As an independent post. 
 
 (d) As a reserve station or rallying point in rear. 
 
 In the first case, strengthen the front and flanks. The rear 
 should be prepared to resist infantry. In the second case, the 
 distance from the main line will govern the amount of prepara- 
 tion. If very distant, should be j^repared for all-round defense. 
 If within rifle range, the rear should he left open, so that in case 
 the village is taken, recapture will be facilitated. In the tJiird 
 case, if an independent post, must be prepared for an all-roimd 
 defense. In the fotirth case, if in the rear of the main line, must 
 l)e i)repared for a protracted, all-round defense. 
 
PLATE 28. 
 
 C3 House t(ft standing 
 
 □ - fV^Pf^f^ for 
 
 demoiiuoJi. 
 ^S • preparpii for defense 
 mmmm^ K lit refxch mftit 
 ZZZ2,\ Wire entanglement ^f^^2$^' 
 
 L 
 
Defense of Localities. 127 
 
 208.- Whether or not a village is to be held will depend on: — 
 
 (1) Its tactical value as compared with the number of men re- 
 quired to defend it. 
 
 (2) Whether it is practicable to provide a sufficient garrison 
 for its defense. 
 
 (3) Whether it will be possible to demolish the village entirely, 
 in order to deprive the enemy of the cover it provides. 
 
 (4) On the form and nature of the surrounding country, i. e., 
 no commanding ground within artillery range, foreground easily 
 preimred and the unimx^eded advance of the defenders' troops in 
 the required direction easily arranged. 
 
 (5) On the shape of the village — whether broadside, salient, or 
 circular. 
 
 (6) Nature and materials of the houses. 
 
 209.^ — The first points to determine in preparing a village for 
 defense are how much of it will be defended, whether there are 
 buildings suitable for a keep or citadel, and whether or not these 
 are jn-operly located. 
 
 210. — The arrangements for defense would be made in the 
 following order: — 
 
 (1) Clear the ground toward the enemy. (See Chap. V.) 
 
 (2) Cover for the firing line, supports, and reserves. (See 
 Chap. IV.) 
 
 (3) Creating obstacles. (See Chap. VI.) 
 
 (4) Preparing communications. (See Chap. XVII.) 
 
 (5) Constructing retrenchments, citadels, or keeps. (See "Build- 
 ings."') 
 
 211. — The garrison of a village may be estimated at tw^o men 
 to the yard of perimeter to be defended. 
 
 212.— Salient Villag-e. (PI. 28, Fig. 2.) The successive 
 lines of defense must be carried well out to both sides and the 
 flanks well protected, otherwise the enemy may turn them and 
 avoid fighting in the streets. 
 
 213. — Broadside Village. (Fig. 1.) Here the outside 
 fences must be more utilized than the actual buildingS; as the 
 latter are open to fire from artillery. 
 
1-S Defknst-: of Locatjtif.s. 
 
 214. -Circular \'illii<j,v. (PI. 2'J.) Cheat attention must 
 be paid to the proper division of the village into sections for de- 
 fense and preparing and making the communications. 
 
 21 5. In any of the foregoing cases, if cover does not exist for 
 8ui)i)orts and reserves, it must be provided, as the village will 
 I)robably be shelled before being assaulted. 
 
 If artillery is to be used it should be placed on commanding 
 ground, inaccessible, if possible, to the enemy, and so that its 
 tire will sweej) those paits most la\(»i;il)le to the enemy's ad- 
 vance. 
 
PLATE 29. 
 
 8ITY 
 iLFbRNlA- 
 

-^ft^SE ape,. 
 
 CIIAPTEK XIV. Use of Cordage and Spars. 
 
 210. — A rope is composed of three or more strands of fibrous 
 material, iron or steel, twisted together. The strands of fibrous 
 ropes are formed of threads; of iron and steel rojjes, of wires. 
 The size of rope is denoted by its diameter in inches,* and is gen- 
 erally sold by the pound. Fibrous ropes when new and dry 
 stretch considerably, when wet they contract ; advantage is often 
 taken of the latter fact to tighten temporary lashings. Manila 
 rope is only about % as strong as hemp rope ; tarred ropes only 
 about % as strong as untarred. 
 
 217. — A rule approximating to the breaking tveiglit of a new 
 rope, in tons of 2,000 lbs., is to take one-fourth the square of the 
 circumference in inches. The strength of pieces from the same 
 coil may vary 25 per ct. 
 
 Ropes in daily use should not be worked up to greater than 
 I their breaking loads, to 'meet the reduction in strength by 
 wear and exposure. 
 
 21 8.— The .following table gives the approximate breaking 
 loads and weights of new Manila ropes, Swede's hemp center 
 Iron pliable ropes of 6 strands of 19 wires each, and hemp center 
 Steel pliable ropes of 6 strands of 19 wires each, Manufacturers' 
 Tests : 
 
 * In the Navy the size of rope is denoted by its circumference in inches. The method 
 used should be distinctly stated. 
 
i;j2 
 
 Use of Cokdj 
 
 .\(ii; AM) Sl'Alv'S. 
 
 Diam. in 
 inches 
 
 Breaking loads In lbs. 
 
 Weight per 100 ft. 
 in lbs. 
 
 Minimum Size or 
 
 Sheaves in feet 
 
 for Iron and Steel 
 
 Manila 
 
 Iron 
 
 steel 
 
 Manila 
 
 Iron & 
 Steel 
 
 1-4 
 
 780 
 
 
 
 3 
 
 
 
 3-8 
 
 1,280 
 
 5,000 
 
 
 5 
 
 26 
 
 1 
 
 7-16 
 
 1,562 
 
 6,200 
 
 12,000 
 
 QH 
 
 29 
 
 IJ2 
 
 1-2 
 
 2,250 
 
 7,600 
 
 15,000 
 
 8 
 
 35 
 
 2 
 
 ' 5-8 
 
 4,000 
 
 11,000 
 
 24,000 
 
 13.5 
 
 70 
 
 2U 
 
 3-4 
 
 i>,000 
 
 17,500 
 
 36,000 
 
 16.5 
 
 88 
 
 3M 
 
 7-8 
 
 7,500 
 
 23,000 
 
 50,000 
 
 24 
 
 120 
 
 3K 
 
 1 
 
 9,000 
 
 32,000 
 
 66,000 
 
 30 
 
 158 
 
 4 
 
 IM 
 
 14,000 
 
 54,000 
 
 104,000 
 
 45 
 
 250 
 
 5 
 
 1^3 
 
 20,250 
 
 78,000 
 
 154,000 
 
 66 
 
 365 
 
 QH 
 
 I'U 
 
 30,250 
 
 108,000 
 
 212,000 
 
 97 
 
 525 
 
 ^H 
 
 o 
 
 36,000 
 
 130,000 
 
 250,000 
 
 115 
 
 630 
 
 9 
 
 219. — Knots, Hitelies, etc. The standing part of a rojje 
 is any ])art not an end. 
 
 .1 hi(jht is a loop formed in a rope. (PI. 30, Fig. 1.) 
 
 Whipping is securing the end of a rope with twine to i)r('\(Mit 
 it from fraying out. (Fig. 1.) 
 
 Parceling is wrapping a rope to prevent chafin<^- or cutting- 
 against a rough surface or sharp edge. (Fig. 1.) 
 
 Stop)ping or seizing is fastening two parts of a rope- t<)<;('thor 
 without a crossing or riding. (Figs. 1 and 17.) 
 
 Nipper ing is taking turns crosswise between the i^arts to jam 
 them. (Fig. 1.) 
 
 Splicing is joining the ends of ropes by opening the strands 
 and placing them inot one another (Figs. 2 and 3), or by i^utting 
 the strands of the ends of a rope between those of the standing 
 part. (Fig. 4.) 
 
 Boiling or stopper hitch for fastening a rope to a strap or tail 
 block, and to secure a fall while being shifted on a windlass or 
 capstan. (Fig. 5.) 
 
 Overhand knot to prevent the end of a rope from fraying out, 
 from slipping through a block, and the beginning of several other 
 knots. (Fig. 6.) 
 
 Figure of 8 knot, used in making cask i^iers. (Fig. 7.) 
 
PLATE 30. 
 
 TG.2. 
 
 FIG.l 
 
 or Sezzirro ' ' *=* 
 
 FIG. 6 
 
 'ye Sfdtce PIG7 
 
 ^«r^M«/2^^ knot ^^""''^ ¥ ^ 
 
 pIG.ll.,^ FIG.12. 
 
 Sinole bow ^slipknot j.^ TT^ ^ Square or , . Thie/^ GrnrnM 
 
 FIG 13. ^-^^ tfk ^^FIG14. .^ 
 
 (c m 
 
 hitchy. 
 
 FIG. 17, p^^l*'*/'^'^*^ : 
 
 Double 
 'avers knot 
 Sheet bervd. Bend 
 
 FIG.22. 
 
 Timber hitch. 
 
 ^A-ff- 
 
PLATE 51. 
 
 FIG.l 
 
 FIG. 2. FIG. 3^ FIG.4.^ FIG.5. 
 
 Blackwall ^CamckSmd 
 
 IG.9. 
 
 Rack las/ung^^^'''-^ f^y 
 FIG 15 ■^ V\!,\5-^^'^^ SiguZeZashing 
 
 ^^ V ^\K, / FIG. 16, 
 
 Shear IjashinQ 
 
 Gin la^Un^ £A.lf. 
 
 PI. 31, Fig. 7^revewe rcvpe ia tlie three left ami the two extreme right 
 (M'ossiiigs. 
 
Use of Cokdack and Si'Aiis. 137 
 
 Square of reef knot for joining the ends of two ropes the same 
 size. (Fio-. 8.) 
 
 Til ief Ji not (Fig. d), with ends on opposite sides, and Grannij 
 kitot (Fig. 10), by crossing the ends the wrong way, both looking 
 like square knots, are to be avoided, as they will not hold. 
 
 Siiitjle Jh)U' or sU^) knot. (Fig. 11.) 
 
 S<pi(ire hoir, which can be cast off. (Fig. 13.) 
 
 Marlinnpike hitch, used in putting on lashings, etc. (Fig. 12.) 
 
 Sheepshank, used to shorten a rope temporarily without cut- 
 ting. (Fig. 14.) 
 
 Tico half hitches, for fastening the end of a rope around its 
 own standing part. (Fig. 15.) 
 
 Round ttirn and ttvo half hitches, to secure guys to stakes, etc. 
 (Fig. 16.) 
 
 Fisherman/ s hend or Anchor knot, for fastening a rope to an 
 anchor or ring. (Fig. 17.) 
 
 Weavers knot or sheet hend, for joining ropes of different sizes 
 without jamming. (Fig. 18.) 
 
 Doid)le sheet hend, more secure than the single bend. (Fig. 19.) 
 
 Clove hitch, for fastening a rope to a sj^ar; the end may after- 
 wards be stoppered to its own part. The clove hitch differs from 
 two half hitches only in being made around a spar or other rope 
 instead of around its own standing part. (Fig. 20.) 
 
 Timher hitch jams when made round a timber. (Fig. 21.) 
 
 Bowline, to form a temporary loop at the end of a rope. (Fig. 
 22.) 
 
 BowJine on a hight, to make a loop on a bight. (PI. 31. Fig. 1.) 
 
 Cat's pau', for applying a purchase or tackle to the fall of an- 
 other. (Fig 2, the beginning; Fig. 3, how applied.) 
 
 Blackicall hitch, for fastening the end of a rope on a block in 
 the simplest manner, or fastening a rope in a hook. (Fig. 4.) 
 
 Mousing is a seizing placed around a hook to prevent it from 
 spreading or unhooking. (Fig. 4.) 
 
 Carrick hend, to fasten guys to a derrick. (Fig. 5.) 
 
 Lark's head, for fastening a bight to a ring. (Fig. 0.) 
 
 Capstan or Prolonge, making fast a spar. (Fig. 7.) 
 
 Wall knot, for finishing off the end of a rope to keep from un- 
 stranding (Fig. 8), by passing the strands, as shown, then draw- 
 ing them down into a knot. 
 
\->^ I'sK oi- ( '()!:i) \(.i-. AM) Si' \i:s. 
 
 Fn([>pin(j is i>iissiiig a rope around a Jasliiii^- to kc^i) \hv turns 
 to<,^ether. (Figs. 14, 15 and 16.) 
 
 Straps ?iVG rings used for attaching tackles to spa is or ropes. 
 (PI. 3;3; Figs. 1, 2 and 6.) 
 
 220. To make a slioit splice. (PI. 30, Fig. 2.) Unlay 
 strands of each end for a convenient length ; take an end in each 
 hand, place end to end, strands sandwiching, and grasp the three 
 strands from opposite rope in left hand. Take a free strand, pass 
 it over the first strand next to it, then through under the second 
 and out between the second and third from it, then haul taut. 
 Pass each of the remaining six strands in same manner, first 
 those of one end and then those of the other, and so continue as 
 far as desired. 
 
 221. To make a loii*:^ splice. (Fig. 3.) Unlay strands 
 of each end, 3 or 4 times longer than for short splice, and place 
 end to end as described. Unlay one strand a considerable dis- 
 tance and fill up its space with opposite strand from other rope, 
 and twist them together. Do the same with two strands on other 
 rope. Open remaining strands, divide in two, make overhand 
 knot with opposite halves, and lead ends as in short splice. Cut 
 off the other two halves. Do the same with the other pairs of 
 strands where twisted together. Before cutting off any of the 
 half strands, first stretch, roll under the feet, and pound the rope 
 well. This splicing does not increase the size of the rope and is 
 used where the spliee is to run through blocks. 
 
 222. To make an eve-splice. (Fig. 4.) Unlay one end 
 for short distance, lay strands upon the standing part so as to 
 form the desired sized eye. Put first end through the strand next 
 to it. Put second over that strand and through second. Put 
 third through third strand on other side of rope and so continue. 
 This forms a permanent loop in end of rope. 
 
 223. — To sliii|2: a box or barrel. Lay a long strap under 
 it. spreading the parts, and pass one bight through the other ; or, 
 make a long loop witli a l)owline' and sling as show^n on PL 31, 
 Fig. 11 If one head is out stand barrel up. put one part of a strap 
 under middle of 1) )ttoni, take ii half hitch over top with each part 
 just over bilge hoops and exactly opposite ; or place rope under 
 V)arrel, bring up over top. make overhand knot, open it out and 
 slip each half down over hoops, fasten end to standinii' part with 
 bowline. (Fig. 10.) 
 
PLAIE'32. 
 
 FIG.l. _FIG.2 FIG. 3.- FIG.4. 
 
 FIG 5. 
 
 
 ■Wig. 6. 
 
 FIG 7 
 
 FIG 10 
 
 HrryBlock 
 
UsE~OF Cordage and S['aks. 141 
 
 224.— liack lasliiiigs (Figs. 11, 12 and 13) are made with a 
 }{ in. rope, 18 ft. long with a loop at one end, and a rack stick 
 2 ft. long, IJ^ in. in diameter having a cord 4 ft. long through one 
 end, by passing the rope two or three times around the side rail 
 and balk, and, after making it fast, twisting it tightly with the 
 rack stick. 
 
 225.— Transom lasliiii<>:. (Fig. 11.) The spars are laid 
 across each other at right angles, a clove hitch is made on one of 
 the spars, the end then twisted around its standing part, then 
 three or more turns are taken around the spars, under one and 
 over the other, keeping outside previous turns on one spar and 
 inside on the other. Several frapping turns are then taken be- 
 tween the spars and the end fastened on one of the spars with a 
 clove hitch. Used in lashing transoms to standards in bridge 
 building. 
 
 226.— Shear lasliiiig. (Fig. 15.) The spars are laid par- 
 allel, a couple of inches apart, on a block, a clove hitch made on 
 one spar, then 5 or 6 turns taken around both spars without rid- 
 ing. Several frapping turns are then taken between the spars 
 and the end fastened on one of the spars with a clove hitch. This 
 is used in rigging shears for hoisting heavy weights, etc. 
 
 227.— Gill lasliiiig. (Fig. 16.) The three spars are laid 
 parallel, a couple of inches apart, the butts of the two outside 
 ones in one direction, that of the middle one in the opposite direc- 
 tion. A clove hitch is m-ade oi^ one spar, then 5 or 6 loose turns 
 taken, passing over and under, without riding. Several frapping 
 turns are taken in each interval and the end fastened on one of 
 the spars with a clove hitch. 
 
 228.— 351c)eks, Tackles, etc. Ajndley consists of a wheel, 
 having a grooved rim for carrying a rope, turning in a frame. (PL 
 32, Fig. 1.) 
 
 A block (Figs. 2 and 3) consists of one or more grooved pulleys 
 or sheaves turning on an axle, called a pin, mounted in a casing or 
 shell, which is furnished with a hook, eye or strap on one end, by 
 which the block may be attached to something and sometimes 
 with a l)ecket on the other end for attaching ropes, etc. It is used 
 to transmit power, or change direction of motion, by means of a 
 rope or chain passing round the movaV)le pulleys. Blocks are 
 single. dou])le, treble, or fourfold, according as the number of 
 sheaves oi- jjiillcys is one, two, three or four. The size of blocks 
 
142 Use op Cordage and Spars. 
 
 is expressed by the length of the shell in inches. A common style 
 of Ferry Block is shown in Fig. 5. 
 
 A snatch block (Fig. 4) is a single block with a notch cut in one 
 cheek so as to receive the standing part of a fall without the 
 trouble of reeving and unreeving the whole. 
 
 A riuming block is one attached directly or indh*ectly to the 
 object to be raised or moved ; a standing block is one fixed to 
 some permanent support. 
 
 229. xl tackle consists of-e»€ or more blocks with a rope rove 
 through them for use in hoisting. 
 
 230. — The parts of all ropes between the points of fastening 
 and sheaves are called standing parts; the parts between the 
 sheaves are called running parts ; the part to which the power is 
 applied is called the fall. 
 
 231. — To overhaul di tackle is to separate the blocks; to round 
 in is to bring the blocks closer together. 
 
 A tackle is said to be block and block or two blocks when the 
 entire fall is hauled through so the blocks are in contact. 
 
 232. — Before reeving a rope in a block, it should be stretched 
 out its full length. Tackle should not be allowed to twist; to 
 prevent it, insert a bar in the block or between the running parts 
 and use it as a lever to hold straight. If allowed to make one 
 complete turn with 2 single blocks, the friction will increase the 
 resistance about 40^. Ropes should not be too large for blocks, 
 the rule being, ^^ Small i^opes ami (>/'(/ hJocks:' 
 
 233.— PoAver of Tackle. Theoretically, the power neces- 
 sary to just balance a weight, with a tackle of two blocks, is 
 equal to the weight divided by the number of ropes at the run- 
 ning block. 
 
 234. — To produce motion, however, a greater power is required 
 to overcome friction and stiffness of rope. It has been found by 
 experiment that to do this about 10% of the theoretical power 
 necessary to balance must be added to itself for each of the 
 sheaves over which the rope passes, the blocks being in good con- 
 dition and well oiled. If not in good condition and not well oiled, 
 the per cent may be as high as 30 for each sheave. 
 
 235. — The formula P =r ^^^'^ is used to determine the power 
 required to raise a weight with a simple tackle, in which P = the 
 powder required ; W =: the weight to be raised, S = the number 
 
PLATE 33. 
 
 /'i'p/d /'h/'.y/r//i 
 
 i ^'-nrv"f 
 
 Pta 
 
 a 
 
 Sectiork 
 
 w/^^J^ 
 
 v7rr,y^y!j}f 
 
 ^/1 
 
Use ok Cokdacje and Spars. 145 
 
 of sheaves, and K, = the number of ropes tit running block, in- 
 cluding standing part if attached to it. If it is required to find 
 how great a weight a certain power will lift the formula is 
 W = -^. Power is gained only at the loss of time. The power 
 moves as many times faster and farther than the weight as the 
 number of ropes at the running block. No advantage is gained 
 by using, in one fall, a greater number of sheaves than two treble 
 blocks, but may be by a combination of blocks and tackles. 
 
 236. — A squad of men hauling on a fall exert a jjull of about 
 80 lbs,, or half their weight each, the fall being nearly horizontal. 
 
 237. — A Derrick (Fig. 7) usually consists of a single spar 
 or leg, held up by 4 guys, and having a tackle lashed to the top, 
 used for hoisting or lowering heavy bodies within a circle whose 
 diameter equals the height of the spar. When made of 2 legs 
 (Fig. 8) they are mortised into a cap on top and a sill at the bot- 
 tom, only two guys being required, a fore and back, but three are 
 better, one fore and two back. The weight can only swing be- 
 tween the legs. The holdfasts for the guys should be at a dis- 
 tance from foot of derrick at least twice its height. The foot 
 should be secured from slipping by being let into a hole in the 
 ground or otherwise. 
 
 238.— Sliears (PI. 33, Fig. 1) consist of two spars, of a size 
 suitable for the weight to be raised, lashed together at the cross. 
 
 A tackle is fastened at the lashing by a strap passed around it 
 or otherwise, the hook moused, and holdfasts are required as for 
 two-legged derrick. 
 
 Derricks and shears should not lean to exceed }^ of their 
 height and each leg should have about ^4 this inclination. 
 
 239.— A Gill (Fig. 2) is a tripod formed of three poles. The 
 two outside ones are called legs, the third one the jn-y pole. Gins 
 require no guys. Weights can only be lifted vertically. 
 
 240. — In using derricks, shears, and gins, the h\\\ is generally 
 led through a snatch })lock lashed on a leg near the bottom, thence 
 to a crab, windlass, or capstan. Derricks frequently have fas- 
 tened on their legs (/ winch for transmitting the power. (PI. 32, 
 Fig. 10.) 
 
 2-1-1. — A Windlass (Fig. 12) consists of a horizontal axis 
 fastened in a frame and turned l)y means of cranks or handles. 
 The n)])e may cither be fjistcned to the axis or passed two or tliree 
 
140 Usi: OV roiJDAflE AND SlWKS. 
 
 times around it, hauled tiiut, the free end being held, and taken in 
 by men in the rear. 
 
 242.— A Capstan (Pi. 32, Fig. 9, and PL 33, Fig. 3,) consists 
 of an upright barrel, either smooth or ribbed, arranged about a 
 spindle. Above the barrel is the head with holes to Teceive the 
 ends of levers or bars by which the barrel is revolved. The rope 
 is passed and held as explained for a windlass. 
 
 243. — Holdfasts are stout wooden stakes driven into the 
 ground, or oilier ;ii ranj^ements used for securing purposes. 
 
 An essential ]K>int to be considered before moving or suspend- 
 ing heavy weights is the nature and condition of the securing 
 points, together with the strain that will be brought upon them. 
 In the first instance, it is better to make them more secure than 
 seems to be absolutely necessary, as, when they once begin to give 
 way, it is difficult to strengthen them. PI. 33, Figs. 4, 5, 6 and 7, 
 show some of the various methods of making them, also PI. 40a. 
 
PLATE 34. 
 
^ w The f 
 
 UNIVEK8ITY 
 ClIAPTEK XV. Spar Brid^^os. 
 
 li-A-i. — Mililary Bridg-es are not required to fultil all the 
 conditions of ordinary bridges. They are constructed for special 
 and immediate purposes, usually with unskilled labor, and of 
 such materials as can be procured on or near the spot. That the 
 bridge built shall be strong enough to bear the heaviest load in- 
 tended to be crossed is the first requisite; celerity and siniijlicity 
 of construction next. 
 
 245. — PL 34 is an illustration of what was done in building 
 Military Railroad Bridges under unfavorable circumstances in 
 time of war with troojjs of the line, very few of whom were me- 
 chanics, many could not even handle an ax, none were trained to 
 the duty, and none were engineer troops. This bridge was built 
 by General Haupt over Potomac Creek, Va. ,during the Rebellion, 
 and was 80 ft. high and iOO ft. long. It consisted of three tiers of 
 trestles on top of cribs 12 ft. high. The timber used was chiefly 
 round sticks, cut in the woods near by, and put together without 
 bolts, simply with spikes and wooden pins, and, when finished, 
 was crossed by 10 to 20 heavily loaded trains per day. This kind 
 of work, however, properly belongs to a special construction corps, 
 but it falls to the lot of the officers and men who first arrive at a 
 stream on the ordinary roads, where there are no means of cross- 
 ing, to construct ^n improvised bridge with such tools and of such 
 materials as may be available. 
 
 24:G. — The jjlans and expedients which follow have been 
 selected with a view to their being types of bridges that can be 
 ccmstructed by troops having no other tools than axes and augers, 
 and such materials as growing trees found in the vicinity, and 
 beams, boards, ropes, wire, nails, etc., obtained from neighboring 
 houses and towns. The i^urposes for which the bridge is to be 
 used, the nature of the crossing, velocity of stream, and kind of 
 bottom, will determine its strength, kind, size, etc. 
 
150 Si'Ai: Ukijj(,ks. 
 
 247.— Foi- a coiiinion road bridge, the load is assumed to be a 
 maximum when covered with men, estimated at 120 lbs. to the 
 sq. ft., pins the woi<,4it of the bridge, usually taken at about 80 
 lbs. per lineal It. For reasons which are evident, the bridge 
 should be as sliort as possible, with good approaches. Swampy, 
 high, or steep banks should be avoided. 
 
 248. — Bridges usually take their names from some part of their 
 construction, as Treatle, Truss, Pile, Suspension, or Floating 
 Bridges. The distance between supports (determined by the 
 strength of the balks to bear the desired load) is called the hay or 
 span, and the corresponding part of the bridge the span. The 
 superstrffcfKrc, consisting of the stringers or balks, the floor, the 
 side-rails and the fastenings, is of the same nature for each kind, 
 as shown in PI. 35, Fig. 1. The ends of the balks rest on cross 
 I^ieces of the supports called transoms, on the balks (of which 
 there are usually five) are laid chess or poles, forming the floor ; 
 on top of the floor, over the outside balks, are laid side-rails or 
 poles, which are securely fastened every 4 or 5 ft. to the balks be- 
 neath by rack lashings. Hand-rails (Fig. 2) should always be 
 provided on each side of the roadway. The usual width of mili- 
 tary bridges is 9 ft. in the clear, between side-rails; 6 ft. will 
 answer for Infantry in column of two's, and Cavalry by file ; 2.5 ft. 
 for Infantry in single file. 
 
 249. — For determining the strength of the materials to be 
 used, all errors should be on the side of safety. The practical 
 method is to place the ends of the timber on low supports, as far 
 apart as they will be in bridge; as many men as can, then step 
 on it and jump up and down ; or it is otherwise arranged so as to 
 bring as great a weight upon it as it will have to bear at any time 
 in bridge. 
 
 Where small poles of the usual number would not be strong 
 enough, a greater number must be used until the desired strength 
 is gained. 
 
 250. — Transoms must be strong enough to bear all the weight 
 that may be brought upon one bay of the bridge, considered as 
 distributed dead load on the transom. 
 
 261,— The load in pounds which any timber resting on two 
 points of support will safely bear, concentrated at its center, may 
 
 bd^ 
 be approximately determined by the formula ^ x -p- x C, in 
 
PLATE 35. 
 
 Of Tue ^n 
 
 'FORM I A. 
 
Spak Bkidces. 153 
 
 which b ~ the breadth in inches, d 1=: the depth in inches, 1 = 
 the length in feet between supports, and C is a constant in 
 pounds for the particular material of the beam * * is the frac- 
 tion of the breaking weight used for safety. It would, in all 
 cases, bo better to use a smaller fraction of the breaking weight, 
 as i or i; or even | in cases of importance or of a permanent 
 character. The formula is for a rectangular beam, but for a 
 cylindrical timber whose mean diameter equals the side of a 
 square beam, use ^^o of what the formula gives. 
 
 2 o'2,— Weight brought on a bridge by the passage of troops^ 
 taken as distributed live load for Infantry and Cavalry : Infantry 
 in column of twos or fours about 225 lbs. per lineal foot. In- 
 fantry when crowded at a check in fours about 550 lbs. per lineal 
 foot. Cavalry in column of twos about 230 lbs. per lineal foot. 
 Cavalry when crowded at a check about 350 lbs. per lineal foot. 
 When Artillery carriages cross a bridge, the weight is not equally 
 distributed, bat in greatest when the ivheeh bearing the heaviest 
 load ((re on tlic center. 
 
 25:J. A uniformly distributed dead load produces only one- 
 half the strain of an equal dead load concentrated at the center. 
 A moving or live load produces twice the strain of a dead load. 
 A uniformly distributed live load equals a concentrated dead load. 
 
 Table of Constants, C, for finding the breaking load of various 
 
 bd2 
 materials by the formula I x -y- x C when concentrated at cen- 
 ter of beam supported at both ends. From "Trautwine's Engi- 
 neer Pocket Book :" 
 
 Ash, white. ... 650 Elm 350 Oak, red and black 550 
 
 Ash, swamp. . . 400 Hemlock 400 Pine, white 450 
 
 Ash, black .... 300 Hickory 700 Pine, yellow 500 
 
 Beech, white. .450 Hickory, pig nut. .500 Pine, pitch 550 
 
 Beech,red 550 Locust 600 Poplar 550 
 
 Birch 450 Mahogany 450 Spruce 450 
 
 Cedar 250 Maple 550 Sycamore 500 
 
 Chestnut 450 Oak, white and live 600 Walnut 450 
 
 *U is deterniined by taking a piece 1 in. square, and 1 ft. long between supports, load- 
 ing it at the center until it breaks, then to the applied. load adding one-ha^f the weight 
 of the piece between supports, and the sura will be C ; or, a piece of any convenient size 
 and length can be used, afterwards deducing what the breaking weight would be for a 
 piece 1 in. square and 1 ft. long, remembering that the breaking weight varies directly 
 with the width, as the square of the depth, and inversely as the length. 
 
'•'' Si'\i: I Jk'i i)(,i:s, 
 
 254. 77/(^ ('((hie contents of a log^ is approximately equal to 
 0.7854 times the square of the mean diameter times the length, or 
 the area of the mean section multiplied liy the length; or the 
 square of one-tifth the mrjin circiiinfc^-cncc times twice the 
 length, all in feet. 
 
 255. In calculating the strength of a round timber or spar, 
 its mean diameter is used, because such a spar, if overloaded, will 
 break at center, instead of at small end.* 
 
 25(>. The following ta))l(' ui\cs the w.-iuhts in lbs. prv cu. ft. 
 of various materials: 
 
 Chestnut 40 Spruce ;U 
 
 Cottonwood 35 Sycamore 37 
 
 Hickory 43-49 Walnut 38 
 
 Maple 48 Clay 120 
 
 Oak 45 GO Earth 71M20 
 
 Pine. 34 40 Gravel & sand.90 130 
 
 from I to J more than those in table. 
 
 257. WIk'ji sjinrs jiic used for balks, they nnist ])e arranged 
 so as to have all butts ov all tips together on a transom. They 
 should have good overlap and be well lashed to each other and 
 the transoms. To allow for settling, the centre is generally made 
 higher by about 3',, tlic span. 
 
 Iron, cast 
 
 \vi-ou,u-ht . 
 Lead 
 
 ...450 
 
 ...487 
 .. .710 
 
 Steel 
 
 . ..188 
 
 Ash 
 
 :\s 47 
 
 Cedar 
 
 ....,35 
 
   K.T a hridjjTo constructed as in Kig. '^, witli (> lialk-^, tn (Ict.riniiic the ^.itC 1();m1 it will 
 (■an,\ . ilif aiip icatioM will be about as follows: 
 
 The balks heinj? of yellow pine, 10 inches in diameter at the center, 25 ft. between sup- 
 f, 1 103 
 
 . ports, the fornuila jrivts ^o ^ ;V "^ 2.5 ^ ^^ = ^.^^ ^bs. as the safe load each balk 
 
 will bear concentrated at the center, including its own weight. Calculating for 5 balks« 
 on the supposition that the two out5<ide ones receive only M the strain of the center 
 ones, they will bear 5 x 4,000 lbs. = 20,000 lbs. concentrate 1 at center. From this deduct 
 half the weight of the balks and floor concentrated at centei-, found ])y multiplying M 
 the cubic contents by the weight per lb : for the (> balks this will be 
 
 6 X I r / 5\2 X .7854 1 X 25 X 40 = 1636.25 lbs. 
 For the floor of 50, 4-in. poles, each 12 ft. long, the weight will be 
 
 .^0 X I X r (1)' X .78.">4 1 X 12 X 40 = 1047.24 lbs. 
 2(l,(M)0 lbs. — •,' tlS.S .') lbs. = 17 :516.:> lbs., the capacity of the bridge concentrated at the cen- 
 t.i'. Infaiitiy inanliing in column of fours crowded by a check would cause a load of 
 only about i:'. T.M) lbs. (\ivalry in column of twos crowded by a check only about 8,750- 
 lbs. 
 
 Similarly, knowing the siian the kind of material at hand, the weight to be borne, 
 etc., the size of timbers rcciuird can be deduced; oi, having the size and kind of the 
 timbers, weight to be borne, etc , the greatest length that can be spanned can be deter- 
 mined by the above formula 
 
 Foot nt)te pg. 154, for ''lb '' read '-ft." \veight of floor deduced for 50 . 
 poles siiould be for 75. ^-^<*.^^ 
 
REESe ^/ 
 
PLATE 36. 
 
 FIG.l. 
 
 PIG. 2. 
 
 FIG.3. 
 
Spar Bridges. 15T 
 
 258.— i^or spans of 25 feet or less, if timber is available, the 
 simplest form of stringer bridge could be built, as in Fig. 2, of 6 
 balks, 30 ft. long, reaching clear across, covered with small poles 
 4 to 6 in. in diameter, 12 ft. long, for a floor. Side -rails would be 
 laid on the floor over the outside balks and either lashed or 
 pinned to the balks. Hand-rails would be as shown or a rope 
 stretched across would answer. Time of construction — 1 hour. 
 The balks could be jumped across as shown in either Figs. 3 or 4. 
 
 259. — If stringers of length to reach across cannot be obtained 
 or are too heavy to handle easily, a bridge as in Fig. 5 might be 
 made, requiring only axes and augers. The shore stringers, 25 ft. 
 long, 10 in, in diameter, six on each shore, have their bridge ends 
 scarped on upper side 18 in., then pushed out 10 ft., their shore 
 ends being well anchored down and loaded with roadway. Six 
 short stringers, 8 ft. long, 10 in. in diameter, three on each shore, 
 scarped 18 in. on under side of each end are passed orer gap and 
 laid on shore stringers. Two 2-in. auger holes are bored at each 
 end through both stringers and wooden pins driven through, and 
 the flooring completed. 
 
 260. — Paiiie's Bridge. (Fig. 6.) If timber is abundant and 
 stream not over 6 ft. deep, select trees up stream. Fell, and trim 
 off branches. Bore two 3-in. auger holes near butt ends 3 in. 
 apart, making an angle of 30° with each other, and a third hole, 
 making an angle of 45°, between them nearer the butt. Cut and 
 insert in outside holes legs long enough to raise the butt the de- 
 sired height of bridge. Float down stream, butt end first, to posi- 
 tion of bridge. On arriving in line of bridge, the log is turned on 
 its feet, the tip sinking to bottom. The brace leg is then inserted 
 down strea'm in last hole making an angle of 45°. Log after log 
 is thus placed, balks rolled up and put into i30sition and leveled 
 and the floor laid in the usual way. 
 
 201. — For spans of 25 ft. or over, when bottom can be touched 
 clear across, some form of trestle bridge will be the easiest of con- 
 struction. 
 
 202.— In PL 36, Fig. 1, the trestle consists of 6 legs, 4 vertical 
 and 2 inclined ; the two vertical legs on each side are fastened to 
 two short sills by 2-in. pins. The ends of the two inclined legs 
 are cut on an angle, driven into position and held by 2-in. pins 
 passing through the transom from above. Theyserve as braces 
 and supports. A short horizontal piece pinned to each pair of 
 
158 SpAii Bii]i)(ii<>'. 
 
 vertical legs sui)ports the transom, which is also pinned. On top 
 of the projecting ends of the vertical legs a cap piece can be 
 pinned to form hand-rails. The trestle is made on shore, floated to 
 its place in bridge, and erected with the aid of a float held at the 
 proper distance from last trestle by a pole on each side, having 
 the lengths of the sp^ins marked by pins which engage the tran- 
 soms of the trestles. The transoms are only temporarily lashed 
 in position at first, but after the trestle is erected in its proper 
 place the proper height for it is determined by bringing the 2 
 distance poles horizontal, or a little above the horizontal if a cam- 
 ber is to be given, then pinning or spiking on the short horizontal 
 pieces. If accurate soundings have been made across the stream 
 on the lines of the legs of the trestles, then the trestles can be 
 completed on shore before launching. The balks are then run 
 across and pinned and roadway finished. If there occurs unequal 
 settling, the roadway can be raised by blocking up under the tran- 
 soms on the short horizontal pieces. 
 
 2()8. Fig. 2 is another form of trestle (ailed the Tio-block 
 Trestle, consisting of only two legs, about 8 in. in diameter. 
 The transoms are in pairs, across which two blocks are spiked at 
 each end into notches, as shown. This trestle can be used on 
 hard, uneven bottom. The trestle is formed on shore, held in 
 shape by the rope, and rack stick across the top, then floated into 
 place. Two poles, longer than two spans, are then run out; on the 
 projecting ends are pins to prevent tlie trestle slipping otf, and on 
 near end a rope for fastening to transoms of second trestle back. 
 Having caught the trestle on the ends of the poles under the tran- 
 som, it can be raised to a vertical position by men bearing down 
 on the rear, and held by means of ropes ; it is then lowered into 
 position, legs in a vertical plane. The transoms are then adjusted 
 to their proper elevation by striking on under side, if too low, then 
 tightening rope; or by slackening the rope and striking on upper 
 side if too high. When properly adjusted, the rope is tightened, 
 pinching the legs between the blocks ; the braces are then spiked 
 or pinned on, the rope removed, the balks laid and pinned, and the 
 poles shoved out for the next trestle. 
 
 264. — Where sufficient lumber can be procured, the most ex- 
 peditious and probably the best method will be as follows : (Fig. 
 3.) With the balks and chesses for each span, form a raft, or as 
 many as may be desired, the length of a span. Form a trestle by 
 
Spar Buiikjks. 159 
 
 placing 4 legs parallel and 4 ft. apart from center to center. Spike 
 a pole across near the bottom and one near the top to keep them 
 together. The first, or any trestle, having been set, float a raft 
 against it and make fast ; bring the trestle to be set up to the 
 other end ; force the legs under the raft a distance a little less than 
 the depth of the water. Tie a rope around the outside legs at 
 "f " with a bow-knot, to hold from slipping under, and others to 
 the top pole, by means of which it is raised to a vertical position 
 when it is dropped to the bottom by slackening off on lower ropes. 
 As soon as it is dropped, another raft is brought up, tied, and an- 
 other trestle put into position, and so continued. Each trestle, as 
 soon as it is in position, is then capped by nailing two boards hor- 
 izontally on opposite sides of legs with tops in same plane. (Fig. 
 3, a.) Braces are then spiked on the legs. Saw off the two inside 
 posts even with the tops of boards. Spike a 2-in. plank across the 
 top of posts and boards. Lay the balks, spike them, remove the 
 raft, and move it into position to raise another trestle. If boards 
 cannot be procured for capping, round sticks may be used as in 
 Pig. 3, b, by cutting the two inside legs off 5 or 6 in. above the 
 horizontal poles, then spiking two short pieces across the poles 
 against the outside legs and one in center on which the cap piece 
 or transom will rest. Advantages are — work can be commenced in 
 any number of places at the same time; no accurate soundings 
 required so long as poles are sufficiently long ; capping and bracing 
 do not retard work ; different squads can be at work at same time, 
 etc. 
 
 265. — If only axes and rope are available, trestles may be made 
 by lashing their parts together. Pig. 4 shows the Two-legged 
 Trestle. Having determined the height of the roadway above 
 the bottom of the stream, mark this height from the butts on both 
 legs, then mark the position of the transom on the legs, allowing 
 for the thickness of the balks ; also mark on the transom for the 
 width of roadway between side-rails plus 3 ft., for points of cross- 
 ing of legs, the distance apart of legs depending on width of 
 roadway. Give the legs a splay outwards at the bottom of ^ and 
 mark on legs and ledger the points of lashing. All being ready, 
 lay the transom on a couple of supports 3 or 4 in. high, inside the 
 position of the legs, lay oa the legs in their proper positions, on 
 the legs lay the ledger. With the square lashing fasten the four 
 points of crossing. Next, lay on the braces, butts and one tip on 
 
I'J*' Si'AK l>KI l)(,KS. 
 
 same side as leilger and one ti^j on side of transom. Lash the 
 butts with square lashings. Square the trestle by making the 
 diagonals equal, measuring from the centre of ledger lashing on 
 one leg to the centre of transom lashing on opposite leg. When 
 these diagonals are made equal the tips are lashed with square 
 lashings and the braces at the middle with a cross lashing. Led- 
 ger and braces can be of rather light timber. The trestles can be 
 floated into position and raised as already described, or run out 
 and down from the end of the bridge, which is more difficult. 
 They are kept vertical by lashing the balks to tlie transoms, and 
 longitudinal bracing from one to another. 
 
 26(). A Tliree-legged Trestle (PL 37, Fig. 1) may be 
 made by first lashing two legs together considerably higher than 
 the roadway is to be, then lashing the pry-pole just below to one 
 of the legs, all with shear lashings. Stand the trestle up, spread 
 out legs till butts rest on the vertices of an equilateral triangle 
 whose sides are J height of trestle, then lash three light 
 ledgers to the legs by round lashings. On the outside of the pry- 
 pole and leg to which it is fastened are lashed short pieces, by 
 square lashings, on which rest two longer pieces, separated by the 
 legs, which are lashed together by the shear lashing. On these 
 longer pieces rest the transoms. With these trestles lighter ma- 
 terial can be used ; they stand without bracing but are difficult to 
 place; accommodate themselves to inequalities of surface; the 
 roadway may be readily raised or lowered. If material is avail- 
 able, they are readily made with spikes. 
 
 267. — Fig. 2 is another form of trestle of four legs. Two two- 
 legged trestles are made, one being 12 to 18 in. narrower than the 
 other, depending on the size of legs, S3 that they will lock when 
 put together. The transoms are placed on same side as ledgers, 
 instead of on opposite sides. The butts of the single trestles are 
 I)laced a distance apart equal to half the height, then locked at the 
 top, the transoms lashed at the ends, longitudinal braces lashed at 
 the ledgers, the tips tied and racked together. Sometimes used 
 with light material, also as steadying points in a long bridge of 
 two legged trestles. One similar to it can l)e made of sawed tiiii 
 ber and spikes and jjlaced in position as shown in Figs. 3 and 1, if 
 the materials are available. 
 
 268. — In sluggish streams with muddy bottoms and not owv C) 
 ft. deep, where timber is abundant, crib piers may be used. (Fig. 
 
PLATE 37 
 
PLATE 38. 
 
 UNIVLKSITl 
 FIG. 4. S/nn/r I.orA' . ^vC4L|F0RN\^ . 
 
 JA^ 
 
Sf'Ai: 13i:ji)(iES. 165 
 
 5.) The cribs are built in the woods, the foundation lo^s bein^ 
 Xjinned together, the others simply notched. The logs are then 
 marked, taken down, carried or floated into position, and re- 
 built, poles being generally set to mark the corners. As the crib 
 is built up it gradually sinks, or a tray may be formed inside and 
 loaded with stones. The balks and flooring are laid as usual. 
 
 209. — Pile bridges are scarcely adapted to an emergency, from 
 the time and preparation required in their construction, but on 
 linos of communication, from the character of the bottom or the 
 dangers from floating objects, resort may be had to them. 
 
 2 TO. — For driving the piles, a monkey (Fig. 8) is made of a 
 block of wood 3 ft. long, 12 in. in diameter, with four 1.5 in. i)ins 
 at top and four on the sides for handles. Four men standing on 
 a platform on the pile drive it down, their own weight thus assist- 
 ing, or they maybe driven from a raft built as in Fig. 6. After the 
 piles are driven they are straightened, braced, their tops sawed off 
 level, the caps i)laced on and pinned (PI. 38, Fig. 1), and the roadway 
 laid as usual. Piles near shore may be driven as in Fig. 7. 
 
 271. — For crossings greater than 25 ft. and too deep to use any 
 of tlie above forms, resort must be had to some form of t)-uss 
 bridcjc. The trusses may be put together either by lashing or with 
 pins, or by combinations of both. 
 
 272. — PI. 38, Fig. 2, rejjresents the ordinary Kiiig'-post 
 Truss for spans up to 40 ft. The bridge is imt together on the 
 bank, then pushed forward halt* its length, using rollers under 
 ea-ch truss, as shown. A trestle is then leaned forward from oppo- 
 site bank, and, when truss is over it, the trestle is raised and the 
 end of the truss carried over to the opposite bank. 
 
 273. — Fig. 3 represents the Qiieeii-iiost Truss for spans up 
 to 50 ft. It is constructed and carried across similar to the pre- 
 ceding one. 
 
 274.- Fig. 4 shows the Siiigle-I^ock for spans of 30 ft. It 
 consists of two frames similar to the two-legged trestle on PI. 36, 
 Fig. 4. A section of the gap is first marked out on the ground on 
 each bank with the positions of the footings indicated. On these 
 the legs are laid and the positions for lashing the transoms and 
 ledgers marked. The frames are then put together opposite the 
 I^osition they are to occupy (one on each bank), butts towards the 
 gap. One frame is made 15 to 18 in. wider than the other so they 
 will lock, and the footings should be likewise prepared. The dis- 
 
H>t> Siwii Bi;iik;ks. 
 
 tance between Icj^sat traiisoiuof nari-ower rraiuc is 18 in. more than 
 width of roadway between side-rails. With the above exceptions 
 the frames are made like the two-legged trestles. The splay of 
 the legs is very slight, generally about 1 ft. between transom and 
 ledger. Stout stakes are then driven at the rear, fore and back 
 guys are attached to the tips of each frame, the fore guys crossed 
 over the stream, those of narrower frame in center. Foot ropes 
 are also attached to each leg near the butts with timber hitches 
 and a turn taken around the stakes at the rear. The frames are 
 then shoved over the banks till they balance (PI. 40, Pig. 1) then 
 brought to a vertical position by hauling on the fore guys, and 
 lowered into their places by easing off on the foot ropes, after 
 which they are pulled over and locked. A couple of balks are 
 then run out, then the fork transom is put into place and the 
 balks rested on it. The remainder of the balks are then run out, 
 placed on the fork transom, lashed, and the roadway completed as 
 usual. If good places for footings cannot be secured, then other 
 means must be provided. 
 
 275.— For spans up to i'> or '>(> fl.. i\\v Doiible-Tjock (PI. 
 39, Fig. 1) may be used. In this it will be noticed that the balk- 
 bearing transoms are not the transoms first lashed to the frames 
 in making them, but those which are sent out after the frames 
 are in position. This must be remembered in marking the posi- 
 tions of the transoms on the legs of the frames. In this the two 
 frames are made as described for the single-lock, except that they 
 are of the same width. They are launched as described, and 
 pulled forward until their tops are about ^ the span apart. Two 
 straining beams are then run across, the road-bearing transoms 
 fastened on top of them in the positions previously marked. The 
 frames are held by the back guys until all is ready, when they 
 are eased off and the bridge locked. The roadway is then laid as 
 usual. 
 
 270. — Fai- sjxn/s greater than 45 or 50 /^, where timber of 
 sufficient size is obtainable, the Single Sling or Treble Sling 
 may be used. The frames are made as has been described, with 
 the following additional observations: 
 
 In the Single Sling (Fig. 2), in marking the positions of the dif- 
 ferent spars, the three locking pieces must be at least 9 or 10 ft. 
 above the roadway. The fork piece is hauled into position by 
 snatch blocks lashed to the top of each leg of narrower frame. 
 
PLATE 39. 
 
 Double Lock 
 
 ^^.^ -:s^^ 
 
PLATE 40. 
 
Spar Bkidge^. 171 
 
 after which the blocks are used to get the center transom tempo- 
 rarily into position, when it is slung by the ropes that are to hold 
 it, by taking several turns around it and the locking pieces with- 
 out riding, and afterwards twisted up to the proper height with a 
 pole. 
 
 277. — In the Treble Sling (Pig. 3) there are three slung 
 transoms, one from the forks and one from the standards on each 
 side of the middle. The frames are constructed as already de- 
 scribed. (PI. 10, Fig. 2, being one in plan.) If necessary, the 
 frames may be strengthened by additional braces on them and 
 further braced back to the banks by ropes attached to holdfasts 
 and otherwise as suggested on PI. 40, Figs. 1 and 5, vertical braces 
 being shown in Fig. 3. 
 
 278. — Other expedients for crossing small gaps are the use of 
 wagons in various ways for supports, brushwood made into 
 gabions, fascines, etc. (Figs. 6 and 7.) 
 
 279.— A liglit, portable truss (Fig. 11) can be made, 
 where boards are obtainable, by describing two arcs of circles 
 with radii 151 ft., on opposite sides of a 60 ft. chord, then driving 
 stakes on the arcs at intervals of about 2 ft., against which 5 
 layers on top and 6 layers on bottom of boards 1 in. thick x 12 in. 
 wide, breaking joints, are bent and securely nailed together every 
 1 in. with tenpenny nails. The lower side of truss is made one 
 board thicker than the upper and is completed by driving G in. 
 spikes through every 6 in. This truss will be about 6 ft. deep, 
 and, allowing 2 ft. at each end for resting on supports, will bridge 
 a span 56 ft. 
 
 The sides are connected every 5 or 6 ft. by vertical pieces of 
 I)lank and two 1-in. iron rods, the latter on the sides of the verti- 
 cals, towards the middle. If iron rods are not obtainable, rope or 
 wire should be wrapped aro\md both and twisted tightly. The 
 angles at the ends are filled with wedge-shaped pieces and the 
 ends securely bolted, hooped, or wrapped. (Fig. 9.) For greater 
 rigidity, light diagonal braces may be inserted in the panels. The 
 top can be made straight instead of curved if so desired. 
 
 These trusses are used in pairs and are applicable to a variety 
 of structures and to spaces of considerable width. Two such 
 trusses with a central support of trestles, crib-work, or boats, may 
 be used for 116 ft. (Fig. 11); three such trusses for 176 ft., etc. 
 In experiments with such trusses in bridges, 1,800 lbs. per lineal 
 
172 Spar Bridces. 
 
 foot has been applied before breaking; and by covering the boards 
 with pitch and tar before nailing together, inserting % in. bolts 
 in pairs every foot of length on lower side, and nailing boards 
 against the edges, 3,500 lbs. per lineal foot was applied before 
 breaking. 
 
 280. Siisi)tMisi<)ii l>i'i(l<>'es. For spans greater than 60 ft., 
 and when timbers for frames cannot be procured, some form of 
 suspension bridge might be used. Although applicable to longer 
 spans, and the materials more easily transported, they take longer 
 to make than other kinds. 
 
 The cables may be of iron chains, iron, steel or fibrous ropes, 
 or of boards nailed together. 
 
 281. — PI. 40a, Pig. 1, shows one with the roadway hung below 
 the cables, with a camber ^^y. At the center, the roadway should 
 be at least 1 ft. below the cables. The width of roadway between 
 side rails should be only slightly wider than wagon-wheel tracks. 
 (Pig. 2.) On the banks, the cables are supported by timber piers 
 (Pig. 3), having a broad cap (Pig. 4), rounded on top, over which 
 they pass at a distance apart of 9.5 ft. The cables must be 
 securely anchored at the rear to heavy logs sunk 4 or 5 ft. in the 
 ground, or otherwise, and drawn in until the sag is only ^^y or ^\ 
 of the span. 
 
 282. -In Pig. 5, part of the roadway is hung below and a part 
 rests on the cables, the greatest slope of road being 1 on 6 for 100 
 ft. span and ^q sag. The cables are only 7 ft. apart. 
 
 283. — In Pig. 6, the roadway is built on trestles supported on 
 the cables. Por spans 130 ft., sag ^^, the frames form the sides of 
 equilateral triangles of 10 ft. each. To construct it, the curve of 
 the cables is traced on the ground, the trestle legs laid on it and 
 marked where they cross the road and cable ; those for each half 
 of the bridge are ranged in order on the banks, connected to- 
 gether as placed on the cables and hauled out, connected at the 
 center, the curve of the cables adjusted and the bridge completed. 
 
 284. — Pig. 7 is a suspension bridge of which the cables are 
 made of boards nailed together in several thicknesses laid hori- 
 zontally, breaking joints; the ends are spread apart and wedge- 
 shaped blocks inserted and anchored by several rows of posts, as 
 shown in Pig. 8. Each cable, as made, is drawn across by ropes^ 
 anchored, and the trestles placed from both ends at the same 
 
Spar Bridges. 173 
 
 time. Last of all, spikes loDg enough to reach entirely through 
 the cable are driven every 4 to 6 in. 
 
 285. — Fig. 11 is a similar bridge supported on trestles 16 ft. 
 long, not exceeding 20 ft. high, placed at intervals of 40 ft., over 
 which suspends the two board cables, 14 ft. apart. On these are 
 placed low trestles, 3 ft. high, dividing the spans into lengths of ' 
 20 ft. each ; 25 ft. balks are used and the roadway laid as usual. 
 The cables are made of six thicknesses, of 1 in. boards 12 in. wide, 
 breaking joint, nailed and spiked every 4 to 6 in., and bolted by 
 pairs of % i^- bolts every foot. Three thicknesses of boards are 
 first nailed together and drawn across, the ends anchored, and 
 then the other three boards added. 
 
 280. — For light foot bridges (Fig. 10), across narrow gaps, wire 
 from fences, if available, could be used. for the cables by twisting 
 a number together and passing them over crotches of trees and 
 anchoring to stumps, etc., in rear, and then laying the walk simi- 
 lar to some of the methods previously shown. 
 
 287. — So various are the conditions to be met in constructing 
 bridges that seldom will any one type meet the requirements, but 
 by the application of good judgment and resource, with the sug- 
 gestions here offered, almost any gap of reasonable width may be 
 crossed, if not by one type or another, then by a combination of 
 several to meet the emergency. 
 
 The varying strength of timbers makes it almost impossible to 
 give exact dimensions for the different spars to be used in the 
 different types, but a general idea may be obtained below of.the 
 amounts and average dimensions of medium strength timber, as 
 yellow pine. For weaker timbers some of the sizes will have to 
 l)e increased, while for stronger ones there will be an excess of 
 strength if the sizes given are adhered to, but the desire to be on 
 the side of safety warrants the use of amounts which might, by a 
 careful mathematical calculation, appear to be excessive. 
 
 The timbers for transoms, ledgers, braces, balks, flooring and 
 side rails should be selected of as nearly a uniform diameter 
 throughout as possible and will be so considered in giving dimen- 
 sions. For legs or standards the diameter at tip will be given. 
 
 For a 9 ft. roadway with 15 ft. spans, 5 balks 20 ft. long x about 
 G in. in diam. are used, and placed 2)4 ft. apart from center to 
 center. For the flooring are used poles 11 to 12 ft. long x 4 to 5 
 in. in diam. For side rails 2 poles 20 ft. long, 4 to 6 in. in diam. 
 
174 Spar Bridges. 
 
 For eacli Six-legged Trestle (PL 36, Fig. 1) 1 vertical and 
 2 bracing legs 6 in. diam., 1 transom 12 ft. x 8 in., 2 foot pieces 3 ft. 
 X 8 in., 10 oak pins 2 in. diam. 
 
 For eacli Tie-block Trestle (Fig. 2) 2 legs 8 in. diam., 2 
 transoms 15 ft. x 8 in., 4 tie blocks 2 f t. x 5 in. x 6 in., 2 braces 3 ft. 
 X 2 in. X 6 in., 24 spikes, 1 rope, 1 rackstick. 
 
 For eaeli Capped Trestle (Fig. 3) 4 legs 8 in. diam.; 2 
 braces 12 ft. x 4 in.; 2 braces 15 ft x 5 in.; 3 boards 12 ft. x 2 in. x 
 12 in.; 4 ropes, spikes. 
 
 For eacli Two-legged Trestle, lashed, (Fig. 4) 2 legs 4 ft. 
 longer than height of trestle, 5 to 7 in. tip ; 1 transom 15 ft. x 9 
 in.; 1 ledger 16 ft. x 4 to 6 in.; 2 braces 3 to 5 in. diam.; 6 ropes 30 
 ft. x J in. diam.; 3 ropes 15 ft. x | in. diam. 
 
 For eacli Tliree-legged Trestle, lashed, (PI. 37, Fig. 1) 6 
 legs 3 to 5 in. tip ; 4 transom bearers 6 ft. x 3 to 4 in.; 4 sticks 2 
 ft. x 2 to 3 in.; 6 ledgers 2 to 3 in. diam.; 1 transom 15 ft. x 9 in.; 
 12 ropes 30 ft. x J in. diam.; 6 ropes 15 ft. x | in. diam. 
 
 For eacli Four-legged Trestle, lashed, (Fig. 2) twice the 
 amount given for each two-legged trestle, plus 2 ledgers, and 6 
 lashings 15 ft. loii^-. 
 
 For each Single T.ock (PI. 38, Fig. 4) 4 legs 22 to 25 ft. x 7 
 in. tip ; 1 ft. transom 15 ft. x 10 in.; 2 frame transoms 15 ft. x 6 in.; 
 
 2 ledgfMs 15 ft, X 4 to 6 in.; 4 braces 20 ft. x 3 in.; 2 shore sills 15 
 ft. xG ill. LdsJiinys, 4 transom 50 ft. x | in.; 10 ledger and 
 brace 30 ft x J in.; 10 balk 20 ft. x }, in.; 4 foot 50 ft. x 1 in.; 8 guy 
 150 ft. x 1 in. 
 
 For each Double Lock (PL 39, Fig. 1) 4 legs 22 to 25 ft. x 
 7 in. ti]) ; 2 straining beams 25 ft. x 8 in.; 2 road transoms 15 ft. x 
 10 in.; 2 frame transoms 15 ft. x 6 in.; 2 ledgers 15 ft. x 5 to 6 in.; 
 4 braces 20 ft. x 3 in.: 2 shore sills 15 ft. x 6 in.; Lashings, 8 tran- 
 som 50 ft. x I in.; 14 ledger and brace 30 ft. x J in.; 10 balk 20 
 ft. X J in.; 4 foot 50 ft. x 1 in.; 8 guy 150 ft. x 1 in.; besides axes and 
 other tools, and anchorages, holdfasts, etc., on banks. 
 
 For each Single Sling (Fig. 2) 4 legs 35 to 45 ft. x 6 in. tip; 
 
 3 top and fork transoms 15 ft. x 6 in.; 3 road transoms 15 ft. x 10 
 in.; 2 ledgers 15 ft. x 4 to 6 in.; 4 braces 20 ft x 3 in.; 2 shore sills 
 15 ft. x 6 in.; 10 balks 30 ft. x 6 in.; 4 side rails 30 ft. x 4 to 6 in. 
 Lashings of same number, size and length as for Double Lock. 
 Stiffening will require additional spars and lashings, depending 
 upon the method used. 
 
PLATE 40a. 
 
 Fig.8. Fig. 4 
 
 Fig.6 
 
 Fig. 10 
 
 ^.Af\. 
 
Spar Bridges. 175 
 
 For eacli Treble Sling (Fig. 3) 4 legs 50 ft. x 6 in. tip ; 5 
 
 road transoms 15 ft. x 10 in.; 3 top and fork transoms 15 ft. x 6 
 in.; 2 lower ledgers 15 ft. x 4 to 6 in.; 4 lower braces 20 ft. x 3 in.; 
 4 upper braces 18 ft. x 3 in.; 2 shore sills 15 ft. x 6 in.; 15 balks 5 
 ft. longer than ^ span x 6 in.; 6 side rails 5 ft. longer than ^ span 
 x 4 to 6 in.; 6 sling racking sticks 10 ft. x 4 in. Lashings, 4 foot 50 
 ft. X 1 in.; 8 guy 150 ft. x 1 in.; 24 ledger and brace 30 ft. x | in.; 
 8 transom 50 ft. x | in.; 40 or 50 balk 20 ft. x i in. Stiffening 
 will require additional spars and lashings, depending upon the 
 method used. 
 
 For Suspension Bridge 200 ft. long (PI. 40a, Fig. 1) 4 to 8 
 cables 180 ft. x 1 in.; 16 cable seizing of yarn 18 ft. long ; 12 lash- 
 ings 50 ft. X I in.; 10 lashings 30 ft. x i in.; 100 lashings 20 ft. x | 
 in.; 2 steel wire cables 400 ft. x 1| in.; 4 standards 26 ft. x 10 in. 
 tip ; 4 braces 22 ft. x 3i in. tip ; 2 caps 12 ft. x 10 in.; 2 sills 15 ft • 
 X 10 in.; 4 back struts 36 ft. x 4 in. tip ; 4 side struts 32 ft. x 3 in. 
 tip ; 4 cable props 30 ft. x 5 in. tip ; 4 horizontal ties 30 ft. x 3 in. 
 tip ; 21 transoms 10 ft. x 6 in.; 80 balks 13 ft. x 6 in.; 40 side rails 
 20 ft. X 6 in.; for anchorages 16 spars 5 ft. x 7 in. tip ; 2 spars 16 ft. 
 X 20 in.; 2 spars 16 ft. x 12 in. f round ; 10 spars 16 ft. x 8 in. f 
 round ; 4 back ties 50 ft. x | in. steel rope ; 4 ties 35 ft. x ^ in. steel 
 rope ; 40 slings total 600 ft. x J in. steel rope ; 4 guys.50 ft. x 1 in.; 
 4 rope ladders. 
 
 For Suspension Bridge 100 ft. long (Fig. 5) 4 to 8 cables, 
 12 cable seizings, 4 lashings, 12 lashings, 30 lashings as above ; 2 
 cables 180 ft. x 3 in. hemp or 2 in. steel ; 2 anchor spars 18 ft. x 15 
 in.; 10 transoms 12 ft. x 4 in.; 4 balks 25 ft. x 6 in.; 10 side rails 20 
 ft. X 4 in; materials for piers depending on circumstances. 
 
 For Suspension Bridge 130 ft. long (Fig. 6) 4 to 8 cables; 
 12 cable seizings, 9 lashings, 104 lashings, 280 lashings as above ; 4 
 cables 200 ft.x2| in. hemp or 1| in, steel ; 2 anchor spars 18 ft.x 18 
 in.; 44 trestle legs 13 ft. x 3 in. tip ; 44 braces 15 ft. x 2 in. tip ; 22 
 transoms 9 f t. x 4 in.; 80 ledgers 12 ft. x 2 in.; 20 cable ledgers 12 
 ft. X 5 in.; 2 shore sills 10 ft. x 5 in.; 48 balks 14 ft. x 5 in.; 28 side 
 rails 20 ft. x 5 in.; materials for piers depending on circumstances. 
 
 Besides the above materials, there will be required tools for 
 cutting timber, tackles for raising frames, shovels, pickets, etc., 
 and, where not mentioned, the ordinary amounts of balks, chess, 
 side rails, etc. 
 
CHAPTi:n X^ I.— Floatino liiidoc 
 
 288. — Tlie i>assage of a stream may be effected, in many 
 cases, as described in the preceding chapter. If the methods 
 there hiid down are not suitable or expedient, and the stream can- 
 not be forded, then resort must be had to ferry int? by boats, rafts, 
 flying bridges, or to floating bridges. 
 
 289. — Tlie selection of a place and means of crossing a 
 river is determined by a reconnaissance, which should be as de- 
 tailed and extensive as circumstances will permit, and oml)race 
 the following:— 
 
 (a) The nature of the banks. 
 
 (b) The nature of the bed. 
 
 (c) Position and dei^th of fords. 
 
 (d) Strength of the current. 
 
 (e) Whether tidal or otherwise. 
 
 (f) Probability and extent of floods. 
 
 290. — Fords. A stream with a moderate current may be 
 forded by infantry when its depth does not exceed 3 ft., and by 
 cavalry and carriages when its depth is about 4. ft. The requisites 
 of a good ford are: — 
 
 (a) Banks low, but not marshy. 
 
 (b) Water attaining its depth gradually. 
 
 (c) Current moderate. 
 
 (d) Stream not subject to freshets. 
 
 (e) Bottom even, hard, and tenacious. 
 
 291 .- In a mountainous country, the bed of a stream is likely to 
 be covered with large stones, rendering the passage of carriages 
 impracticable. In level countries, the bed of the stream may be 
 composed of mud or quicksand, rendering passage by fording im- 
 possible. In some cases, the bottom is composed of fine sand, 
 which is hard enouiih, but wliich. by the action of the hoofs of the 
 
' UNIVERSITY 
 
PLATE 41. 
 
 1^ ^ 
 
Floating Bridges. 171) 
 
 animals, is stirred up; the current then carries the sand away and 
 the'ford is deepened, perhaps so much as to become unfordable. 
 The best bottom is coarse gravel. 
 
 292.— Fords are usually found in the wider and more -rapid 
 parts of a stream. A straight reach gives the most uniform 
 depth. At bends, the depth will generally be greater at the con- 
 cave bank and less at the convex. (PI. 41, Figs. 1 and 3.) 
 
 293. — To determine the position of a ford : — 
 
 (1) A number of mounted men may be sent across wherever 
 there is a probability of the river being shallow enough. 
 
 (2) Most certain method. Float down the stream in a boat, 
 keeping in the swiftest part of the current, where the water is 
 usually deepest. Hang a sounding line of the proper length over 
 the stern. When this touches bottom, sound across the stream. 
 
 When a ford is discovered, it should be marked by stakes ; 
 remarkable objects on the shore should be noted ; and a stake 
 planted at the water's edge and marked, in order that any rise in 
 the water may be at once evident. 
 
 294. — A stream, otherwise unfordable, may be passed : — 
 
 (1) By crossing it in a slanting direction. (Fig. 2.) 
 
 (2) When the unfordable portion is not over 8 or 10 yards, this 
 may be filled in with fascines loaded with stones. (Fig. 4.) 
 
 (3) When the bottom is muddy, it may be covered with bundles 
 of coarse grass, rushes, or twigs, sunk by means of stones. 
 
 (4) A portion of the water may be diverted from its natural 
 channel. (Fig. 5.) 
 
 295.^In passing a stream by fording, if it is deep and the cur- 
 rent at all swift, the following precautions should be taken : — 
 
 (a) Troops passing in column should do so at a considerable 
 interval, in order to avoid choking the stream. 
 
 (b) If boats are to be had, a few should be stationed below the . 
 ford, to assist men who may be carried down by the current. 
 
 (c) If boats cannot be procured, mounted men may perform the 
 duties described in the foregoing provision. 
 
 (d) In place of provisions "b*' and "c," a life line, held up by 
 casks, may be stretched across the stream. 
 
 (e) In order to break the force of the current, cavalry may be 
 stationed in the stream, above the point of crossing. 
 
 296. — After a freshet, a ford should always be re-examined, 
 lest some alteration may have taken place in the bed of the 
 
1'^" FU)ATIN(. I>lv'll)(.i;s. 
 
 Rtreani. T1h> i):iiiks of a sli-caiu tn Ix' foiMcd slioukl, if necessary, 
 be scarped. 
 
 The velocity of a stream may be determined by throwing in a light 
 rod, so* weighted as to stand vertically. Note the distance passed 
 over in a certain number of seconds ; then, /g the mean number 
 of feet T)er second ^nves the velocity in miles per hour. 
 
 2J)T. Ice. In lii^h latitudes, during the winter, rivers are 
 ireiiuently covered with ice of sufficient thickness to sustain the 
 heaviest loads. This means of passing a stream should be used 
 with great circumspection. A change of temperature may not 
 only suddenly destroy the natural bridge, but render the river im- 
 passable by any method, for a considerable time, in consequence 
 of floating ice. 
 
 298. Ice, in order to allow of passage, should be of the follow- 
 ing thickness: 
 
 For Infaiiliy. sin^-lc tile. '2 yds. distance, on a line of 
 
 planks 2 in. 
 
 For Cavalry or light guns, w4th interA^als 4 in. 
 
 Heavy tield-pieces 5 to 7 in. 
 
 Heaviest loads 10 in^ 
 
 299. — When there is any doubt as to the strength of the ice, 
 two tracks of plank may be laid for the carriage wheels to run on, 
 or the wagon may be transformed into a kind of sled by fastening 
 two planks under the wheels. (Fig. 6.) 
 
 The thickness of ice may be increased, when the temperature is 
 low, by throwing water on it. When a stream is frozen on each 
 side but open in the middle, in consequence of the velocity of the 
 current, a boom stretched across the open space will often check 
 the velocity sufficiently to allow the water to freeze. 
 
 300. — If a stream cannot be forded, it may be crossed by fer- 
 rying or by constructing a bridge. Ferrying may be by boat, 
 raft, or flying bridge; rowed, sheared, or hauled across. 
 
 301.- Ferrying by Boat. All boats available should be 
 collected and taken to the chosen point of passage. The banks of 
 the stream, if steep, should be scarped to facilitate embarkation. 
 The landing should be farther down the stream than the point of 
 starting. The boats should be arranged along the shore and 
 numbered. Entrance to the boats should be by file, the soldiers 
 taking positions on opposite sides alternately. Where the water 
 
l''i>()Ai'i\(i l)i\'i I)(;ks. 181 
 
 is shallow near the shore, the boat should not approach the bank 
 so closely as to ground as the men tile in. The unloading should 
 ])e made in the same manner us the embarkation, i. e., by file 
 alternately from each side of the boat. During the transit, the 
 men should remain in position and not rise up suddenly when th^;- -, 
 boat lurches. , J^ ^^^ ^ 
 
 In i^assing artillery, the piece should be dismounted. H^rse^lV^-, 
 should, ordinarily, be made to swim. However, if the boats^r^ ^ ""^ 
 large enough, the bottoms may be covered with plank, and tn^^^v:^^Pf>^ 
 horses placed crosswise, facing alternately up and down stream. ^^ 
 
 302. — Ferrying by Raft. Rafts may be made of logs, lum- 
 ber, casks, and other material suitable for the purpose. Their 
 construction is the same as explained for piers of bridges, hence 
 only two expedients will be mentioned here. 
 
 303. — Tlie Canvas Ilaft. No other material being avail- 
 able, small rafts can be constructed by the use of canvas about 8 
 X 12 ft., and brushwood. Wet the canvas to make it water-proof, 
 and lay it out on the ground. Across the width place sticks in 
 layers, the longest near the middle. The sides should be 
 strengthened by heavy sticks placed lengthwise. The pile of 
 sticks should be about 4 ft. wide in the center and sloping off 
 slightly towards the ends, 3 ft. high and 8 ft. long. Over this pile 
 a second piece of canvas, after being wet, should be placed. The 
 sides of the canvas on the ground are now drawn over toward each 
 other and lashed securely with a lariat. The ends are folded 
 neatly, brought up towards each other, and lashed. If care is 
 taken to wet the canvas thoroughly and make it water-tight, this 
 raft will carry three troopers with their arms and accoutrements. 
 By lashing several together, a larger number of men, with their 
 arms and accoutrements, can be carried. 
 
 304. — Rafts of Skins. Bags, made of the skins of animals, 
 inflated with air or stuffed with hay or straw, can be utilized for 
 crossing streams, and have been used from ancient times. 
 
 305. — Rafts are more suitable for the embarkation and landing 
 of troops of all arms than boats. They will carry a larger num- 
 ber each trip, are not so easily injured by the fire of the enemy, 
 and draw little water. On the other hand, they cannot be navi- 
 gated with the same facility as boats, move much more slowly, and 
 hence keep the troops much longer under fire; cannot be directed 
 with certainty on a fixed point when the stream is rapid, and, if 
 
182 i^YoATiNG Bridges. 
 
 the passage is to be effected secretly, the time required for their 
 construction is too long to admit of their use. 
 
 306. — Tlie Floating Bridge. This may be formed of two 
 boats covered with a platform, constructed as follows: — (PI. 42, 
 Fig. 1. — The lashings and side rails are omitted.) From 5 to 7 
 beams of the same thickness are laid across the two boats, the in- 
 tervals between the beams being equal, and such that the cover- 
 ing planks extend 1 ft. beyond the extreme beams. The interval 
 between the boats is such as to allow the beams to extend 2 ft. 
 beyond the gunwales. The beams are lashed to the boats, the 
 covering planks are kept in place by 2 side rails, laid directly over 
 the outer beams, and lashed down to them ; the extreme planks 
 should be nailed down. 
 
 The floating bridge can be navigated by oars with nearly the 
 same facility as a boat. 
 
 307. — Tlie Roi^e Ferry. The rope ferry, which is used in 
 sluggish streams, consists of a floating support, either a raft, 
 floating bridge, or a large boat. It is drawn by hand along a rope 
 stretched from shore to shore. 
 
 308. — Tlie Trail Bridge. This is employed in streams not 
 more than 150 yds. in width, and whose current is not less than 3 
 ft. per second, or 2^ miles per hour. The rope must be main- 
 tained above the surface of the water, and, consequently, must be 
 drawn very tightly by means of a windlass, blocks, and falls, or 
 similar expedients; it must, also, at each bank, be raised some 
 distance above the water. (PI. 42, Fig. 3.) 
 
 The raft, or boat, is attached to a pulley, which runs on a sheer 
 line, and by means of a rudder is given such a position that its 
 side makes an angle of about 55° with the direction of the 
 current. The angle of 55° with the current divides its force 
 against the side of the boat into two components : one, per- 
 pendicular to the sheer line, which is counteracted by the resist- 
 ance of this line ; the other, parallel to it, which moves the boat. 
 A boat for this kind of ferry should be narrow and deep, with 
 nearly vertical sides. 
 
 If a raft is used, it should' be lozenge-shaped, the acute angle 
 being about 55°. When two sides are parallel to tlie current, the 
 
PLATE 42. 
 
PLATE 43. 
 
Floating Bridges. 187 
 
 up-stream side will then be in the most favorable position for 
 passage. (PL 43, Fig. 8.) 
 
 309.— The Flying Bridge. The character of the float for 
 this ferry is the same as in the preceding case. (PL 41, Fig. 7 ; 
 PL 42, Fig. 2.) This bridge is resorted to when the stream is wider 
 than 150 yds. The strain on the sheer line being very great, it is 
 replaced by a cable anchored in mid-stream, in which case the 
 float would swing between two landing piers; or by two cables, 
 one anchored on either bank, the float swinging between four 
 piers. The latter requires less skill in manipulation. The angle 
 which the float makes with the current is the same as that of the 
 •'trail" bridge. A sharp bend may be utilized for anchoring the 
 cable, as shown in PL 42, Fig. 4. 
 
 The length of a swinging cable should be 1% to 2 times the 
 width of the stream. The cable should be supported on inter- 
 mediate buoys or floats, to prevent it dragging in the water. 
 
 310. — Floating Bridges are composed of a roadway and 
 its supports. The roadway is explained in the preceding chapter. 
 The supports are floating, as pontoons, boats of commerce, rafts 
 of barrels, logs, lumber, inflated skins of animals, or other mate- 
 rial. The supports are called floating piers. It is from the 
 character of the support that the bridge derives its name. 
 
 .311. — In constructing a floating bridge, the site should be 
 tirst selected and the u'idth of the stream measured. 
 
 In selecting a site, the following points should be noted: — 
 
 (a) Proximity to a road. As the approaches to floating bridges, 
 having frequently to be constructed across meadows, give much 
 trouble, they should be as short as possible. For a similar reason, 
 marshy banks are undesirable. 
 
 (b) The bed of the stream, if anchors are required, should aftord 
 good holding ground. 
 
 (c) A bridge can be best defended if constructed at a re-entering 
 l)end of a river. 
 
 (d) Use can frequently be made of islands to economize mate- 
 rial. 
 
 312. — In measuring the icidtli of the stream, if it cannot be 
 done directly, some one of the methods explained in Chaj). III. 
 can be used. 
 
 313. — It should be remembered that a wide roadway gives 
 greater steadiness than a narrow one. In making calculations for 
 
l88 Floating Bridges. 
 
 buoyancy, the weight of a 9 ft. roadway may be taken at 80 lbs* 
 per running foot. 
 
 314. — Piers. Of whatever material the floating pier is made, 
 the following points should be observed: — 
 
 (1) The available buoyancy of each pier should be sufficient to 
 support the hea\ iest load that can be brought on one bay of the 
 bridge. 
 
 (2) Piers should be connected with each other, at their extremi- 
 ties, by tie balks or lashings. 
 
 (3) To insure steadiness, the length of a pier should be at least 
 twice the width of the roadway. 
 
 (4) The water way between piers should, if possible, be more 
 than the width of the piers, never less. 
 
 315. — Piers of open boats. In forming a pier of open 
 boats, the following precautions should be taken : — 
 
 (1) The boat should not be immersed deeper than within 1 ft. 
 of the gunwale. 
 
 (2) If the water is rough, or the current extremely swift, a boat 
 should not be immersed deeper than within 1 ft. 4 in. of the gun- 
 wale. 
 
 (3) Boats should be placed lu bridge with bows up stream or 
 toward the current. 
 
 (4) If the stream is tidal, the bows of the boats should be alter- 
 nately up and down stream. 
 
 (5) Unless the boat is very heavy and strong, the balks should 
 not rest on the gunwales; a central transom should be impro- 
 vised by resting a timber on the thwarts or seats, blocking up 
 from underneath and bringing the weight directly on the keel- 
 son. (PI. 43, Figs. 6 and 7.) 
 
 (6) Large boats should be placed where the current is swiftest, 
 also as the first and last boats in bridge. 
 
 316. — Tlie buoyancy of a boat may be found by one of 
 the following rules :^ 
 
 (1) To find the available buoyancy load the boat with unarmed 
 men to a safe depth. Multiply the number of men thus loaded 
 by 160. The result will be the available buoyancy in pounds, 
 
 (2) If the boat is afloat and empty, the available buoyancy may 
 be found by calculating the volume between the then water line 
 and the " safe load •' line, and multiplying by 62J. 
 
Floating Bridges. 
 
 181) 
 
 (3) To find the total buoyancy. If the boat is of nearly uni- 
 form section, the area of the section multiplied by the length of 
 the boat will give the cubic contents. A cubic foot of water 
 weighs 62^ pounds. 
 
 Hence, if the dimensions of a boat are taken in feet, the con- 
 tents will be cubic feet, and this, multiplied by 62|, will give the 
 displacement of the boat ; from this subtract the weight of the 
 boat ; this will give the total buoyancy. 
 
 *}1 7.— To find tlie leiigtli of a bay. — First find the avail 
 able buoyancy of the boat. Then find the weight per running 
 foot of the load the bridge is to bear, and to this, add the weight 
 per running foot of the roadway. Divide the available buoyancy 
 by this sum. The quotient will be the distance from center to 
 center that boats should be placed apart. Thus: — Suppose the 
 weight per running foot is 480 lbs., that the roadway is 80 lbs. 
 per running foot. .'. 480+80r=:560. The available buoyancy is 
 found by one of the preceding ruleS; to be 5,600 lbs. .*. 5,600-j- 
 560=10. ^ ^ 
 
 318.— The open boats may be: — (1) Those of commerce usually 
 found on streams. (2) Regularly constructed pontons. (3) Im- 
 provised boats. 
 
 The first class requires no description. The second class com- 
 prises the canvas ponton used in the Advance Guard Train, and the 
 boat or barge used in the Reserve Train, of the U. S. 
 
 319. — The table below gives the dimensions of the ponton in 
 the U. S. Advance Guard Train, shown in PI. 47. 
 
 Canvas Ponton 21' x 5' 4"x2' 4". Weight, 510 lbs. 
 
 Balks 22'x4i"x4i". 
 
 Side Rails same as Balks. 
 
 Chess ll'xl2"xli". 
 
 WEIGHTS FOR ADVANCE GUARD TRAIN. 
 
 Ponton 
 Chess . 
 Trestle 
 Tool . . . 
 Forii'e. 
 
 Wagon. 
 
 Load. 
 
 Total. 
 
 lbs. 
 
 lbs. 
 
 lbs. 
 
 1,750 
 
 1,985 
 
 3,735 
 
 1,750 
 
 1,856 
 
 3,606 
 
 1,750 
 
 2,060 
 
 3,810 
 
 1,700 
 
 1,938 
 
 3,638 
 
 1,217 
 
 1,166 
 
 3,383 
 
190 
 
 Floating Bridges. 
 
 320.--Th3 table below gives the dimensions of the Ponton in 
 the U. S. Reserve Train, shown in PI. 48. 
 Ponton 31'x5' 8"x2' 7". Weight 1,600 lbs. 
 Balks 27'x5"x5" for a 20' span. 
 Trestle Balks 21'8"x.V'xr)". 
 Chess 13'xl2"xli". 
 Side Rails same as Balks. 
 
 WEIGHTS FOR RESERVE TRAIN. 
 
 
 Wagon. 
 
 Load. 
 
 TotaL 
 
 Ponton 
 
 lbs. 
 2,200 
 1,750 
 2,200 
 1,700 
 2,217 
 
 lbs. 
 
 2,900 
 
 2,280 
 
 2,6;^ 
 
 2,100 
 1,166 
 
 lbs. 
 
 5,100 
 
 4,030 
 4,835 
 3,800 
 3,383 
 
 Chess 
 
 Trestle 
 
 Tool 
 
 Forge 
 
 
 321. — Iniprovisecl Boats. To reduce the amount of trans- 
 portation required by an army is a very important consideration, 
 hence the value of the following expedients. 
 
 322.-Tlie Crib Ponton. This boat is 18 ft. long, 5 ft. 
 wide, 2 J ft. deep and covered with canvas. Construction. (1) 
 Let stakes 4 ft. long, 2J in. in diameter, and 2 ft. apart, be driven 
 into the ground, (PI. 44, Figs. 1, 2 and 3), to the dejithof about 1 
 ft., so as to enclose a space of the proper size for the top of the 
 boat. The tops of the stakes should be in the same horizontal 
 plane. This may be tested by placing a straight edge on them. 
 Those that are too high can then be driven down. 
 
 (2) Nail boards against the outside of the stakes, extending 
 4 in. over their tops. 
 
 (3) Cross-pieces, of the same diameter as the stakes, are laid 
 across the tops and pinned down upon them w4th wooden pins. 
 
 (4) Nail the side boards to the ends of the cross-pieces, and 
 cover the bottom of the boat, which in its inverted position is now 
 on top, with boards, and nail the projecting edges of the side- 
 boards to the bottom securely. 
 
 (5) Finish boarding sides and ends to the proper depth. 
 
 (6) The frame is now ready to be covered with canvas. For a 
 boat of the foregoing dimensions, the canvas should be 23| ft. x 
 
PLATE 44. 
 
 Fig. 1. 
 
 Fig. 2 
 
 JW^I^^^SH^fc^^^H^^ 
 
 Fig. 4 
 
 Fig. 6. 
 
 Fig.? 
 
 Fig 5 
 
 a aaammas a^ . ii i i L i l i ii I h ii i i ,i, i i mj.i iM jli , i ukimi WW M 
 
 
Ploatinc} Bridges. 103 
 
 10^ ft., about 6 in. being allowed for lap. The canvas may be put 
 together in any number of pieces by daubing the edges of the 
 seams with a waterproof composition and connecting them with 
 ordinary carpet tacks. 
 
 (7) The canvas having been prepared, it should now be coatt'cl 
 with a waterproof composition. Tallow, put on hot, will do if 
 nothing better can be found. 
 
 (8) Place the canvas on the frame, coated side downward. Tack 
 the canvas to the frame and cover w4th waterproof composition. 
 
 (9) Spike or pin 2 or 3 stout poles to the bottom longitudinally 
 (not shown in drawing) to keep the bottom from abraiding. If 
 these poles are allowed to project about 6 in. at each end, they 
 will assist in launching. 
 
 (10) Loosen the stakes from the ground by means of levers. 
 Turn the boat over and saw off the stakes about 2 in. below the 
 top edge of the side and end boards. 
 
 (11) Pin stout poles to the top of the stakes on the sides and 
 ends, and nail the side and end boards securely to them. 
 
 (12) The side poles should x^roject about 6 in. beyond the ends 
 corresponding to those on the bottom, and be lashed to the bottom 
 poles by means of a rope loop and rack stick. (Not shown in 
 drawing.) 
 
 (13) Turn the canvas over the top poles and tack it dow^n. The 
 boat is finished. 
 
 323. — Tlie Box Ponton. In localities where planks and 
 boards can be conveniently procured, pontons may be constructed 
 very expeditiously by placing two partitions of 2 in. plank, each 5 
 ft. long and 2^2 ft. high, in parallel positions, on the top and ends 
 of which boards are nailed. (PI. 44, Fig. 4.) The box thus formed 
 to be covered with pitched canvas, as described in the mode of 
 constructing crib pontons. Where sound lumber is at hand, the 
 box ponton will be more easily and expeditiously constructed 
 than the crib ponton, but if plank is not at hand it may be prefer- 
 able to use poles or split timber rather than wait for it. 
 
 324.— Wagon Body Ponton. Ordinary wagon bodies, 
 covered with waterproof canvas or india rubber blankets, may be 
 used either as boats or pontons. The small capacity of the wagon 
 body requires such pontons to be placed more closely, to compen- 
 sate for it. 
 
 325. — Piors of Casks. In order to determine the number 
 
lOit Floatinc; l)i:ii)(iKs. 
 
 of casks necessary to form a pier, the buoyancy of a cask must be 
 calculated. This may be done by one of the following rules : — 
 
 (1) Find the contents of the cask in gallons and multiply this 
 by S}^^ ; the result will be almost the total buoyancy in pounds. 
 
 (2) By the formula 
 
 5c2 1 — W X 
 
 in which c is the circumference of the cask in feet half way be- 
 tween the bung and the extreme end; 1 is the length in feet, ex-, 
 elusive of projections, measured along a stave, and W is the 
 weight of the cask in pounds ; x being the total buoyancy. 
 
 If the cask is closed, j^^ of the total buoyancy equals the avail- 
 able buoyancy. 
 
 326. — To find the distance between two piers of casks : Find 
 the available buoyancy of each cask. Multiply this by the num- 
 ber of casks in the pier. This gives the available buoyancy of the 
 pier. To the weight per running foot that the bridge is to bear 
 add the weight per running foot of the superstructure. Divide 
 the available buoyancy of the jjier by this sum; the quotient will 
 be the required distance. 
 
 327. — In regard to p?>rs of casks, the following should be 
 noted : 
 
 (1) That piers of casks, when in bridge, should always be rigidly 
 connected to each other at their ends by tie balks. 
 
 (2) That the tie balks should be lashed to both gunnels of each 
 pier. 
 
 (3) That while the roadway balks may not be lashed to the 
 gunnels and to each other, it should be done if there is much 
 sway on the bridge. 
 
 828. — Piers of Open Casks. This is the simplest and 
 most convenient method of using casks for piers, as it requires 
 only a few nails and poles, dispensing with rojjes which are 
 sometimes hard to procure. 
 
 To make a raft of this kind, as shown in P]. 44, Figs. 5 and 6, 
 stand 10 or 12 barrels side by side, touching each other ; nail 4 
 poles across the outside of the barrels, two at top, two at bottom, 
 the nails being driven from the inside into the poles, which, as 
 the heads are out, can easily be done. Place another row of bar- 
 rels beside the row thus fastened together and nail them to the 
 two poles of this row. Nail two poles to the outside of the second 
 
Floating Bridges. 195 
 
 row of barrels, one at top and one at bottom ; push the barrels 
 thus connected iiito the water. 
 
 If too many rows are connected on land they will become too 
 heavy to handle. Any number of rows, however, can be attached 
 in the manner described above. When the raft is completed, the 
 projecting ends of the poles outside are lashed together, and, at 
 the points of contact of the barrels, a stout wire nail should be 
 driven through and clinched. 
 
 329. — The total buoyancy of a cask may be calculated by the 
 formula given above. If this should be 400 lbs., the safe load for 
 smooth water would be at least 300 lbs.; that is, the available 
 buoyancy is about J the total buoyancy. A square raft of 10 such 
 barrels to a side would carry safely 30,000 lbs. 
 
 330.--Piers of closed casks. The usual method of form- 
 ing large casks into a pier is shown in PI. 43, Figs. 1 and 2. The 
 following are the successive steps in its construction :— 
 
 Stores required for a pier of 7 casks : 7 casks ; 2 gunnels ; 2 
 slings; 12 braces. 
 
 To build a pier of the foregoing stores, 1 N. C. O. and 16 men 
 will be required. The detachment is marched to the site on 
 which the material is placed and forms the casks into piers by the 
 following commands and means, 4 men being detailed as gunnel- 
 men and 12 as bracemen. 
 
 (1) Alig;ii casks. At this command, the casks are brought 
 to the designated place by the bracemen and aligned, touching 
 each other, bung uppermost. 
 
 (2) Place giiiiiiels. At this command, the gunnels are 
 placed on the outer ends of the casks by the gunnelmen. 
 
 (3) Adjust slings. At this command, gunnelmen bring up 
 the slings and stand at the ends of the gunnels, the bracemen be- 
 ing opposite the intervals between the casks. The gunnelmen at 
 one end place the eyes of the slings over the ends of the gunnels, 
 and those at the other end secure the slings to the ends of the 
 gunnels by a round turn and two half -hitches. The bracemen 
 keep the slings under the ends of the casks with their feet. A 
 sling is made of 1 in. rope and of sufficient length for an eye 
 splice 1 ft. long, at one end. 
 
 (4) Fasten braces. At this command, the bracemen, hav- 
 ing provided themselves with braces, pass the eye of the brace 
 under the sling in the center of their interval, the end passed 
 
1 '.♦<■» Floatinc; Bkidges. 
 
 through thi^ eye and the brace hauled taut, the sling being 
 steadied by either loot. The brace is then brought up outside 
 the gunnel, directly over the eye and a turn round the gunnel 
 taken to the left of the standing part. 
 
 (5) Haul taut. At this command, each braceman removes 
 his foot from the sling and hauls up the standing part of his 
 brace with his right hand, holding on to the turn with his left ; 
 as soon as the brace is taut, the turn is held with the left hand 
 and the remainder of the brace in a coil is placed on the cask to 
 the left. 
 
 (G) Cross hi'aces. At this command, each braceman takes 
 the brace of the man opposite him from the cask on his right, 
 passing it between the standing part of his brace and the cask on 
 his left, then back between his brace and the cask on his right, 
 keeping the turn below the figure of eight knot on his own brace. 
 The end is then placed on the cask on his right. Each man then 
 takes back his own brace from the cask on his left, passes it under 
 the gunnel to the left of the standing part, places one foot against 
 the gunnel and hauls taut. 
 
 (7) llock and liaiil taut. The bracemen, assisted by the 
 gunnelmen, at this command, rock the pier backwards and for- 
 wards, the bracomen taking in the slack of their braces. . 
 
 (8) Steady. At this conimand, the bracemen cease h^miag. — ^ 
 ta»4 and take a turn round the gunnel to the left of the previous 
 turns. 
 
 (9) Seevire l)races. At this command, the braces are made 
 fast by two half -hitches round the two parts of their own braces, 
 close to the gunnels, drawing the two parts close together and 
 placing the spare ends of the braces between the casks. 
 
 (10) Turn tlie i)ier to tlie right and adjust sling;. At 
 this command, the bracemen on the left side, assisted by the gun- 
 nelmen, turn the pier on its right side. The bracemen on the 
 left side adjust the left sling. 
 
 (11) TjOAVor tlic ])ier, turn to tlie left, and adjust 
 sling. At this command, the bracemen on the left, assisted by 
 the gunnelmen, lower the pier. The bracemen on the right, 
 assisted by the gunnelmen, then turn the pier to the left. The 
 bracemen on the right then adjust the right sling. The pier is 
 complete. 
 
Floatinc; Bkii)(;es. 11)7 
 
 8^31. -Should the casks be very small, they may be put to- 
 gether as above described, forming small piers. These can then 
 be united in one large pier by cross gunnels. 
 
 332. — Another method of forming casks into a pier is as fol- 
 lows :— (Figs. 3 and 4.) 
 
 Fasten the braces to a balk, two braces for each cask. Stretch 
 out the braces perpendicular to the balk and lay the casks bung 
 uppermost, end to end, on each side of the balk, each cask over 
 its own braces. Upon the cask lay two gunnels, fastened together 
 at the ends and one or two intermediate points by lashings, the 
 distance between the gunnels being less than a bung diameter of 
 a cask. Secure the braces to the gunnels by two round turns and 
 two half-hitches. The lashings connecting the gunnels are then 
 racked up. The two end gunnel lashings are lashed to the balk 
 beneath the casks and these lashings are racked up taut. The 
 pier is then complete. 
 
 333. — The barrels may be held in ^ frame, as shown in PI. 44, 
 Figs. 7 and 8. 
 
 334. — Piers of XiOgs. In order to determine the number 
 of logs necessary to form a pier, the buoyancy of a log must be 
 calculated. 
 
 To find the total buoyancy of a log. Multiply the solid contents 
 of a log by the difference between the weight of a cubic foot of 
 the log and a cubic foot of water. 
 
 335. — To find the solid contents of a log. 
 
 (1) Take a mean of the girths or circumference at the ends in 
 feet and decimals. Square this mean and multiply it by the dec- 
 imal .079^^6. Multiply this product by the length of the log in 
 feet. 
 
 (2) Multiply the square of 1 of the mean girth by twice the 
 length of the trunk. 
 
 330.- The weight per cubic foot of the timbers usually met 
 with will be found in Chap. XV. 
 
 337. — Required the total buoyancy of a pine log whose mean 
 girth is 6 ft. and whose length is 35 ft. 
 Applying rule 2, we have 
 
 fx«x35x2 = 100* cu. ft. 
 100,^ X (62 i - 40) = 100| X 221 = 100.8 x 22.5 = 2,268 lbs. 
 As lumber absorbs water, the availahle buoyancy is taken as % 
 the total buoyancy. 
 
198 Floating Bridges. 
 
 338.— To form a pier of logs. (PI. 43, Fig. 5.) The larg 
 est and longest logs should be selected. Branches and knots 
 should be trimmed off. The ends of the logs should be painted if 
 the raft is to be used any length of time. The raft should be 
 built in the water. Select a place where there is little current 
 and where the bank slopes gently to the stream. Throw the tim- 
 ber into the water and moor it close to the shore. Note the nat- 
 ural position of each log in the water before putting it in the raft. 
 The upstream end of each log should be drawn on shore and bev- 
 eled to a whistle shape, so as to present less obstruction to the 
 action of the current. 
 
 Arrange the timber in the position it is to have in the raft the 
 butts alternately up and down stream, the up-stream ends forming 
 a right angle, salient up-stream. The first log is brought along- 
 side the shore and the end of a plank or a small trunk of a tree 
 fastened with trenails or spikes to it about 3 ft. from each end. 
 The log is then pushed off a little, a second log brought up under 
 the transoms and in close contact with the first. The second log 
 is then spiked like the first, and so on for each remaining log. 
 Care must be taken to place the whistle ends up stream with the 
 bevel underneath, and to spike the transoms perpendicular to the 
 logs. If the stream is very gentle, the up-stream ends of the logs 
 may be parallel to the transom. 
 
 Another method is to lash the logs together and fasten on the 
 transoms with spikes or trenails. Or, lash the logs together and 
 lash the transoms to the logs, tightening the lashings with rack 
 sticks. 
 
 339. — Two additional transoms should be placed on the raft 
 by whatever method employed in putting on the first. They 
 should be the distance of the roadway or platform apart, at equal 
 distances from the center of gravity of the raft, and bear upon all 
 the logs. In order to obtain sufficient buoyancy, and allow suf- 
 ficient water way, several courses of timber may have to be era- 
 ployed. For use in a bridge, a raft should have an available 
 buoyancy of 15,000 lbs. 
 
 340. — If the raft is to be used as a flying bridge, it should 
 have the shape of a lozenge. (PI. 43. Fig. 8.) 
 
 3 41. — Ancliors. Anchors for the U. S. Advance Guard 
 Bridge Train weigh 75 lbs., and for the reserve train 150 lbs. 
 
r^ Of THE ^ 
 
 1BSIVEBBITY 
 
PLATE 45. 
 
PLATE 46. 
 
 Fig 1 
 
 Fig.2, 
 
PLATE 47. 
 
PLATE 48 
 
Floating Bridges. 207 
 
 These will be sufficient for moderate streams. An anchor with 
 the names of the various parts is shown in PI. 45, Fig. 1. 
 
 342.— The distance of the anchor from the bridge should be 
 at least 10 times the depth of the stream, otherwise the bow of 
 the boat or ponton will sink too deep in the water. The direction 
 of the cable must be the same as the current. The anchor cable 
 should be of 1 in. rope and attached to the anchor ring by a fisher- 
 man's bend. A buoy might be attached to the anchor by means 
 of a 3^^-in. breast line, in order to mark its position and serve as a 
 means of raising it. The breast line is attached to the buoy ring 
 by a fisherman's bend and round the shank of the anchor, close 
 to the crown, by a clove hitch. 
 
 343. — The number of anchors will depend on the strength of 
 the current. It is generally sufficient to cast an anchor up-stream 
 for every alternate boat or ponton, and half that number down- 
 stream. If the stream is rapid, every boat should be anchored 
 up-stream. 
 
 If very rajnd, the bridge must be secured to a hawser, as shown 
 in PL 46, Fig. 1. If the bridge is short, ropes can be stretched from 
 the piers to the banks. (Fig. 2.) If anchors are scarce, one may 
 be attached to two piers. (Fig. 3.) 
 
 Before being cast, the anchor should be well stocked. Rafts of 
 casks or timbers bring a greater strain on anchors than boats or 
 pontons. 
 
 344. — Substitutes for Aiicliors. One or two spare wheels 
 with tires and felloes removed. (PI. 45, Figs. 3 and 4.) Two or 
 more pick-axes, laid together or fixed on one handle. (PI. 46, Fig. 
 4.) A harrow with lengthened teeth, loaded with stones. Gabions 
 filled with stones. Large stones or railway irons. Nets filled with 
 stones. Frame filled with stones. (PL 45, Fig. 2.) 
 
 Care must be taken to allow the anchor to fall in good holding 
 ground. For this purpose, a direction oblique to the current may 
 sometimes be allowed. 
 
 345.— Forming Floating Bridges. Floating bridges may 
 be formed in the following ways :— 
 
 (1) By successive pontons or boats. 
 
 (2) By parts. 
 
 (3) By rafts. , ,,, ,„, ''^> 
 
 (4) Byconversion. UNIVERSITY 
 
208 Floating Bridges. 
 
 340.— By Successive Pontons. (PI. 49.) This may be 
 done in two ways : — 
 
 (1) By adding to the head of the bridge, the tail being station- 
 ary. This method requires the roadway material to be carried an 
 increasing distance. The men, however, do not have to work in 
 the water. 
 
 (2) By adding to the tail of the bridge, the head, already con- 
 structed, being constantly pushed into the stream. The materials 
 do not have to be carried so far as in the first case but it requires 
 a number of men to work in the water and is not advantageous 
 where the bank is steep. 
 
 In the first method, those boats or pontons which cast up 
 stream anchors should be moored above the approach to the 
 bridge, the others below. 
 
 347. — By Parts. (PI. 49.) In this method, the boats or 
 pontons are brought close to the shore above the bridge. For 
 convenience in putting the parts together several chess are laid 
 from, the bank to the interior gunwale of one boat or ponton. The 
 boats or pontons forming the part are then brought in place and 
 balks placed on them. The chess forming the roadway are then 
 placed on the balks, excepting a sufficient number at each end of 
 the i)art to allow for the insertion of a bay between the parts. 
 The parts, all constructed as directed, are then placed in position, 
 each part carrying enough material to construct the connecting 
 bay. The parts are joined with each other and with the abut- 
 ment bay, which has been previously constructed. 
 
 348.— By Rafts. Each raft formed of 2 or more piers, is 
 constructed complete and the rafts come into bridge in succes- 
 sion. Each of the methods, bridge by raft and bridge by parts, 
 has the advantage of simultaneously employing a large number 
 of men. (PI. 49.) 
 
 349. —By Conversion. (PI. 49.) In this method, the bridge 
 is put together entire along the shore above the selected site. A 
 tributary stream may be advantageous for this purpose. The 
 bridge is then floated toward the site, care being taken to prevent 
 the i>ivot end from touching the shore and the wheeling end from 
 turning too fast. 
 
 350. — The various methods above described may be combined 
 in the construction of one bridge. 
 
PLATE 49. 
 
I 
 
 Floating Bridges. 211 
 
 The connection of the bridge with the shore may be made by 
 allowing the balks to rest on an abutment sill let about one foot 
 into the ground, or by a trestle. 
 
 351.— If the stream is to remain open to traffic, it is well to 
 have two or more rafts in mid-stream, arranged to swing so as to 
 allow boats to pass, or the halves of the bridge may be swung for 
 this purpose. Usually the passage is made by allowing the rafts 
 or halves to swing with the current ; they are then brought back 
 against the current. 
 
 352. — Floating objects. Some arrangement should be 
 made to protect the bridge from floating objects. This may be 
 done : — 
 
 (1) By a guard of observation, stationed above the bridge, pro- 
 vided with boats containing anchors, grapnels, hammers, chains, 
 etc. The object may be turned ashore, or, if this is not possible, 
 an anchor may be attached to it to break its momentum. 
 
 (2) By a floating stockade, constructed of trees united by chains 
 and forming a continuous barrier to floating objects. Its direc- 
 tion should be about 20° with the current. 
 
 (3) By constructing the bridge by rafts and withdrawing the 
 menaced part, thus allowing the object to float past. 
 
C llAPTER XVII.-Koads. 
 
 353. — The frequent necessity, in the field, for the construction 
 of a short piece of road, or the repairing of existing roads, makes 
 it important that all who may at any time have this work in 
 charge should be familiar with the principal requirements of it. 
 
 354.— Two desirable conditions in a road are that it be 
 straight and level ; where both cannot be obtained, straightness 
 is sacrificed to levelness. Other things being equal, the length of 
 a road may often be advantageously increased 20 ft. for every foot 
 of vertical height avoided. 
 
 355. — liiniiting; Gradient. As levelness cannot always be 
 obtained, various considerations fix limits for the steepness, called 
 limiting gradients, which are to be used only when unavoidable; 
 thus, for a very short distance, as an approach to a bridge, the 
 limiting gradient may be j^ ; a grade of ^^ should not exceed 100 
 ft.; one of -^ should not exceed 200 ft.; 2^0 should ordinarily be 
 the limiting gradient for easy travel, while Jg to ^5 is still better. 
 
 356. — Compared to what he can draw on a level, a horse can 
 draw only about 90% on a grade of jJo? 80% on ^^5 ^0% on ^^, and 
 25% on jS, but for a short distance he can exert 6 times his ordi- 
 nary force. 
 
 357. — A road should, if possible, always rise continuously to 
 its highest point and nowhere descend partially again. 
 
 358. — Widtli. For military purposes roads should be wide 
 enough to allow wagons going in opposite directions to pass each 
 other easily; this is usually taken at 16 ft. For wagons going 
 in one direction only or with turnouts at intervals, and for infan- 
 try in column of fours, or cavalry in column of twos, 9 ft. will suf- 
 fice, and for pack animals 6 ft. At turns in a zig-zag road up a 
 hill the road should be level and the width increased from J to |. 
 
PLATE 50. 
 
 -3fvet 
 
 . Hadadani 
 
 ^l^^ /GAtcle 
 
 £JjJ 
 
Roads. 215 
 
 359. — Form. The best for the upper surface is that of two 
 planes inclined at an angle of about ^^ and joined by a slight 
 curve 5 ft. long. (PL 50, Figs. 1, 2 and 13.) 
 
 Between the road and ditches should be flat mounds raised 6 
 in. or more above the surface with sloping sides covered with 
 sods or stone next to road, forming with roadway the gutters; 
 they serve also to hold up the road material and as warnings at 
 night of the proximity of the ditch. 
 
 On a hill side the surface should be a single plane inclined 
 towards the hill. (Figs. 3, 4, 5, 7 and 8.) 
 
 360. — Road-bed. The surface of the road-bed should be 
 dug out or built up and solidly compacted, either by rolling or 
 ramming, and when ready to receive the road material should be 
 of the same shape as the surface of the finished road, with shoul- 
 ders at the sides to retain the material in place. (Fig. 13.) 
 
 On hillsides of gentle slope, the road-bed is usually made of 
 half cutting and half filling, the lower side of the slope being 
 stepped to retain the earth excavated, (Fig. 3); on steep slopes it 
 is often necessary to both step the slope and build a retaining 
 wall of stone, (Fig. 4); or of logs, (Fig. 5); or of other materials; on 
 very steep slopes it may be necessary to build retaining walls on 
 both sides, (Fig. 7); while in rocky formations the excavated hill- 
 side may be left nearly vertical, (Fig. 8.) 
 
 361. — Drainage. Nothing is of greater importance in road 
 building than proper drainage. It is the life of a road. In a 
 level country it is necessary to raise the road-bed to keep it 
 always free from water. None must be allowed to remain on the 
 surface and all must be drained from beneath. To accomplish 
 this ditches must be dug on both sides of a road on level ground 
 and in cuttings, from 2 to 3 ft. below the road-bed and of a width 
 depending on the amount of water to be discharged. (Figs. 1 and 
 2.) In wet places, low-lying lands, clayey and springy soils, the 
 ditches must be deeper and sub-drains 3 to 5 ft. below the road, 
 emptying at intervals into the side ditches, must be made to keep 
 it dry. (Fig. 1.) 
 
 Rain falling on the surface of the road is collected in the gut- 
 ters on the sides and run into the side ditches by drains at fre- 
 quent intervals. 
 
 On a hillside, between the road and the hill is the ditch, from 
 which the water is discharged through culverts or covered drains 
 
 k 
 
21G Roads. 
 
 under the road into the natural watercourses. Catch drains 
 along the top of the cutting are made to prevent the slopes being 
 washed down and the water from above finding its way to the 
 road. 
 
 Where open ditches are liable to become filled, some kind of 
 covered drain must be used. (Pigs. 5, 10, 11 and 12.) 
 
 Theoretically, a road should be perfectly level, but for purposes 
 of drainage, in the direction of its length, it should have at least 
 a slope of ilg. 
 
 On a steep road, shallow paved water tables extending obliquely 
 across the road are sometimes necessary to catch the water run- 
 ning down the road and carry it to the gutters, or small mounds 
 crossing the road obliquely are substituted. (Fig. 9.) 
 
 362. — The surface of a road ought to be as smooth and as 
 hard as possible, for which purpose various kinds of covering ma- 
 terial are put on the bed. 
 
 As the roadbed must be kept thoroughly dry at all times by the 
 ditches intercepting all ground water, so the stone or other cover- 
 ing must be so thoroughly rolled and compacted that no water 
 falling upon the surface can possibly find its way down to the 
 foundation and through it to the bed. 
 
 3 03, — When roads are made of broken stone the material in 
 the Telford class is composed of two parts: the foundation and 
 the covering. (Fig. 1, right half.) The foundation consists of a 
 uniform thickness of not less than 5 in. of any durable broken 
 stone with bases about 5 in. x 10 in. laid close together by hand, 
 larger faces down, firmly wedged with smaller stones in the inter- 
 stices, and the whole sledged and rolled to a uniform surface. 
 Then a thin layer of binding material, as clay or loam, is 
 sprinkled over it and rolled. On this is put the covering consist- 
 ing of a layer of about 3 in. of broken stone of uniform, well 
 shaped cubical pieces which will pass through a ring from 2 to 2^ 
 in. in diameter, and rolled to a uniform, compact surface. Then 
 another layer of binding material is added and well rolled. 
 Another layer of stones, 3 in. thick, of sizes from 1 to 2 in. in dia- 
 meter is next spread and rolled as before. On this may be spread 
 another binding coat, well rolled, then a thin layer of fine screen- 
 ings or fine gravel free from dirt. Often, where traffic is light and 
 expense large, a single layer of broken stone 4 in. thick is put on 
 the foundation. 
 
Roads. 217 
 
 3()4.— In the Macadam class (Fig. 1, left half) the hand-laid 
 foundation is not used, but generally three layers, each from 3 to 
 4 in. thick, of broken stone and binding coats, as described above, 
 are spread and rolled until smooth and compact. 
 
 For light traffic a single layer of 4 in. is sometimes used. 
 
 305. The best stone is a compact, tine-grained syenite, basalt 
 or trap rock. Hornblend, actinolyte, dioryte, and some other 
 rocks make good material. Quartz and flint, though very hard 
 are brittle, difficult to work, and not so good. Granite, on ac- 
 count of mica in it, breaks up and grinds away too easily. Gneiss 
 is poorer than granite. Slatey rocks generally break up too easily. 
 Limestone, generally too soft, grinds away easily, making a 
 very disagreeable dust. Softer stones may be used for the foun- 
 dations and lower layers but only the hardest and toughest should 
 be used for the coverings. 
 
 3G6. — Earth roads require even greater care in draining, 
 grading, and forming the surface than those described, and a 
 transverse slope, not less than g^)? to hasten the flow of surface 
 water to the gutters. No sods or vegetable refuse should be al- 
 lowed in grading or filling ruts, but gravelly earth, if obtainable. 
 
 Roads are frequently made with a metal portion in the center 
 and earth roads, called ivings, on the sides. (Fig. 2.) 
 
 307. — It is almost impossible to construct a road of clay which 
 will be good in wet weather, but a very sandy road may be im- 
 proved by working a little clay in it. 
 
 308.— For gravel roads the bed is first formed as described. 
 The gravel is screened to remove stones larger than 2| in. in dia- 
 meter and such as are less than f in.; and all earthy matter. A 
 layer of the screened gravel, 4 or 5 in. thick, is then spread and 
 rolled, then another layer of 3 or 4 in. which should also be well 
 rolled. 
 
 309. — Kei^airs. Ruts appearing should be immediately 
 filled in, and traffic directed over all parts of road. Before 
 spreading stones all mud should be cleaned off and the surface 
 picked up a little to allow the new stone to bind into the old, wet 
 weather being preferred, or the stones should be sprinkled. 
 Ditches and culverts must be cleaned as needed. 
 
 3 TO. — In crossing marshy ground that cannot be well drained, 
 logs of suitable lengths laid side by side across the road, over 
 
218 Roads. 
 
 which is spread a covering of earth or gravel, are sometimes 
 used. 
 
 371. — Brushwood, made into fascines and hurdles, may be 
 used the same way as a foundation. With fascines, the top row 
 should extend across the road and be of a length equal to the 
 width of road. (Fig. G.) 
 
 372. — Where lumber is the cheapest material, plank roads 
 may be built by first laying parallel rows of sleepers or sills flush 
 with the ground, about 4 ft. apart, in the direction of the road, on 
 which boards, 3 in. thick by 9 to 12 in. wide and 8 ft. long, are 
 placed crosswise. 
 
 373.— The construction of communications to all parts of a 
 position to facilitate the movement of troops, etc., from one part 
 to another, is almost always a certain necessity. These would 
 rarely be more than temporary, but, if made on the lines indi- 
 cated, as far as time and requirements permitted, so much the 
 better. 
 
 374. — Roads and paths may have to be cleared through woods; 
 wet places made passable by corduroying or filling up with brush, 
 fascines, etc.; and approaches made to ascend steep places. 
 
 Wherever roads cross or separate, signs should be put up telling 
 exactly where each leads. 
 
PLATE 51 
 
 FIG.l, 
 
 FIG. 2. 
 
 F'SH PcAre 
 
 D D D d D n 
 
 \/'ySH PtATes 
 
 ^^^^ (f^^\ 
 
 IT 
 
 ^ ^^o 
 
 F IG 3 //art/brd Bessed Steel lie 
 
 FIG. 4. 
 
 EIG5: 
 
 J^einfifj'ced \\j . V 
 
 w 
 
 FIG.8. 
 
 InterUdcing bolis FIG.7 
 FIG.9. 
 
 1 
 
 =? 
 
 DOUBLE CIHO 
 
 a^ \ _/m^ . 
 
 FIG. 10 
 
 iia 
 
 n n 
 
 H. 
 
 Fl. f^ 
 
 .fi. 
 
 If [1 ii. 
 
 J- 
 
 iy~' 
 
 
 Ti 
 
 
 
 
 b1 
 
 iL 
 
 n 
 
 11' 
 
 10" y 
 
 ■y 
 
 i^ TZi — mr-* 
 
 jStub su/iiph @-= 
 
 FIG 11. 
 
 FIG.12, 
 
CHAPTER XYIII.— Railroads. 
 
 375. — In military operations, the principal duties of troops in 
 connection with railroads will be either the repairing of lines that 
 have been partially destroyed, or the destruction of lines to pre- 
 vent their use by the enemy. 
 
 376.— A railroad, as existing in its completed form, will be 
 briefly described to indicate the state to which it should be 
 brought by repairs after destruction, and to so familiarize one 
 with it as to suggest methods of most effectually destroying it. 
 
 .377. — A railw^ay line consists of a series of straight lines of 
 different lengths, called tangents, which are joined by curves. 
 The roadbed is first prepared with a smooth hard surface (sloping 
 slightly from the middle to each side for drainage) from 10 to 12 
 ft. wide for a single track, and from 21 to 25 ft. for a double track. 
 On this is placed the ballast, from 12 to 24 in. thick, of broken 
 stone, gravel or cinders, etc., for the purpose of distributing the 
 load over a larger surface, holding the ties in place, carrying off 
 the rainwater, affording a means of keeping the ties up to grade 
 line and giving elasticity to the roadbed. 
 
 .378. — The ties are generally of wood, hewn flat on top and 
 bottom, from 7.5 to 9 ft. long, 6 to 10 in. wide, and about 7 in. 
 deep. It is customary to sink them about half their depth into 
 the ballast. Their object is to hold the rails in place and furnish 
 an elastic medium between the rails and ground. The distance 
 apart is usually 2.5 ft. from center to center, but depends upon 
 weight of engines and strength of rails. They should be uni- 
 formly spaced to distribute the weight equally. 
 
 Tie plates (PI. 51, Figs. 3 and 7) are often used to prevent the 
 rails from crushing into the ties. 
 
 .379. — Tests of metal ties in the interests of economy and effi- 
 ciency have been made with satisfactory, results. On some level 
 portions of the N. Y. Central R. R. are used the Hartford pressed 
 
222 Railroads. 
 
 steel tie (Pigs. 1 and 2), to which the rails are fastened by clamps 
 bolted to the tie. 
 
 380. — The form of rail used in the United States is shown in 
 Fig. 3, being the "T" rail, which varies in weight from 12 to 100 lbs. 
 per yard. The mean dimensions of 80 lb. rails are given on left 
 hand side of figure and of 100 lb. rails on right hand side. They 
 are placed 3 ft. apart for narrow gauge, 4 ft. 8.5 in. for standard 
 gauge, while 6 ft. is the broadest gauge in the U. S., measured 
 from inside to inside of head. The tops of rails must be slightly 
 inclined to fit the cones of the wheels. 
 
 381. — The weak part of a track is at the joints. The old 
 method of using chairs under the ends of rails has about ceased, 
 the practice now being to fish the joints by plates (Pig. 1), and 
 angle irons. (Pig. 3.) There are also used what are known as 
 the Reinforced rail joints (Pig. 4), Bridge rail joints (Pig. 8), 
 Double Girder rail joints. (Pig. 9.) 
 
 382. — Rails are fastened to the ties by spikes, the best being 
 made with sharp, chisel-edge points, clean, sharp edges, and 
 smooth surfaces, so as to cut and press aside the fibers of 
 the wood, instead of tearing them. Attempts to increase the 
 holding power by jagged or twisted spikes have been unsuccess- 
 ful. On bridges, interlocking bolts (Pig. 6) are much used instead 
 of spikes. To keep the track in the right line, allowance must be 
 made for the contraction and expansion of the rails, by not plac- 
 ing them in contact at the joints, and the holes for the bolts must 
 be elongated. 
 
 383. — The centrifugal force of a train passing around a curve 
 tends to throw the wheels against the outer rails, which is par- 
 tially counteracted by raising them to throw the center of 
 gravity inward and cause the car to slide inward. Each rail in a 
 curve ought to be bent to fit the curve before being laid. 
 
 384. — On single tracks, there are laid at occasional intervals 
 short pieces of track, called sidings, to enable trains to pass one 
 another. The arrangement for passing from one track to another 
 is the switch, which consists of a single length of rails, movable at 
 one end by a lever, so as to connect with either pair of rails. The 
 simplest form is the stub switch (Pig. 10), which leaves one line 
 always open while the other is continuous. The one in common 
 use is the split or point switch (Pig. 11.) Various devices are 
 used for locking and interlocking switches, to avoid accidents. 
 
tlNlVEBSlTTi' 
 
PLATE 52. - 
 
Railroads. 225 
 
 At the points where the inner rails cross is placed a frog (PI. 52, 
 Fig. 1), which enables the wheels to pass over the inner rail of 
 the other track. 
 
 385. — Crossings occur where two tracks intersect, and consist 
 of four frogs and corresponding guard rails. (PI, 51, Fig. 12.) 
 
 386. — Where one main line passes to another is called a junc- 
 tion and the ordinary switch is used. In crossing from one track 
 to a parallel track the rails are arranged as in PI. 52, Fig. 2. 
 
 387. — A wye, from a similarity to the l^etter "Y," isjan arrange- 
 ment of tracks for turning around engines and cars and connect- 
 ing cross-roads. (Fig. 3.) 
 
 388. — Turntables are platforms, turning on rollers upon an 
 underground circular track, used to transfer engines and cars 
 from one track to another and to turn them around. 
 
 389. — The locomotive engine is the power on railroads. They 
 weigh from 58,000 lbs. to 190,000 lbs. without tender, and from 218,- 
 (X)0 lbs. for passenger to 310,000 lbs. for freight, with tender, all 
 loaded, and draw 2,400 or morb tons on a level. The amount of 
 coal consumed being from 40 lbs. to 70 lbs. per mile run. 
 
 390. — The rolling stock consists of passenger cars for about 60 
 persons, 48 to 52 ft. long, 9.5 ft. wide, weighing from 40,000 lbs. to 
 00,000 lbs.; sleeping cars for 64 passengers, 60 to 70 ft. long, 9.8 *ft. 
 wide, weighing 60,000 lbs. to 90,000 lbs.; mail, express and bag- 
 gage cars, 45 ft. long, 9.3 ft. wide, weighing about 27,000 lbs.; 
 freight cars consist of Box, Refrigerator, Hay, Furniture, Oil, 
 Stock, etc., and are about 34 ft. long, 8.5 ft. wide, weighing about 
 20,000 lbs., capacity 20 tons ; fiat cars, 34 ft. long, weigh 16,000 
 lbs. to 19,000 lbs. Height of top of box cars above rails about 15 
 ft. Freight cars are being rapidly provided with the M. C B. 
 automatic couplers. (Fig. 4.) 
 
 391.^The buildings consist of passenger and freight depots, 
 engine houses, fuel sheds, water tanks, repair shops, and section 
 houses. At convenient points are generally located yards where 
 stock can be loaded and unloaded. It may sometimes be neces- 
 sary, however, to load and unload animals and supplies in the 
 field along a railroad where there are no platforms or other con- 
 veniences, which must then be built. 
 
 392. — A siini)le form of rani]), in the absence of anything 
 better, could be made by taking 3 or 4 i)lanks 3 in. thick, 10 to 12 
 in. wide, and 10 to 14 ft. long, fastening them together side by side, 
 
--< > Kailkoads. 
 
 preferably by footholds nailed across on top, and several cleats on 
 the bottom ; otherwise, by lashing, wiring or by stakes at the bot- 
 tom when in position, and wedges in the car door. The ends on 
 the ground should be slightly sunken and rested against a cross 
 beam. Ropes should be hung along the sides and blankets or 
 canvas hung on them. Props of some kind, as sacks of grain, 
 bales of hay, etc., can be placed under the middle to strengthen 
 it if necessary. 
 
 .393. — Another form of jmrtahJe tamp, which could be carried 
 on all railroad trains where they might be needed, consists of G 
 long timbers 4 in. x 4 in. x 14 ft., 6 short timbers 4 in. x 4 in. x G 
 ft., 24 boards 1.5 in. x 12 in. x G ft. with footholds nailed length- 
 wise on one side. 
 
 To load or unload horses, rest the ends of three of the long tim- 
 bers, equally spaced, on the car floor, the other ends resting 
 against a short timber, sunk in the ground and staked down. On 
 these place the boards forming the floor; on each side of the 
 ramp, on the boards, lay a long timber and fasten the ends to the 
 timbers underneath. The boards should have cleats on under 
 side to prevent slipijing sideways. If necessary, some of the re- 
 maining boards can be set edgewise between posts of the short 
 timbers as an intermediate support. 
 
 394. — To unload amimherof cars, enough men can be placed 
 under the ramp, near the car, to raise it high enough to allow the 
 car to be removed and another run in place, thus avoiding tak- 
 ing the ramp apart for each car, 
 
 395. — Semi-permanent platforms and ramps may be made as 
 in Figs. 6 and 7, if rails and boards are available. 
 
 396. — To load or unload ivagons and guns from a flat car, 
 place the ramp against one end (Fig. 8), using four long timbers 
 for stringers on which the boards are placed, the other two long 
 timbers being used for side rails. Support underneath with 
 boards set on edge, held between some short timbers, or with 
 bales of hay, sacks of grain or otherwise, as necessary. A couple 
 of boards can be used to run the wheels from the car on to the 
 ramp and others at the foot of ramp to carry the wheels across 
 the rails. The lower ends of the stringers should abut against a 
 tie, if possible ; if not, they should be staked down. 
 
 397. — PI. 53, is a design of a jjortable ramp devised by Major 
 E. G. Fechetj 6th U. S. Cavalry. The ramp consists of 7 boards 
 
PLATE 53. 
 
 Major E.C.FecHKT, 
 
 6^ Cavalry. 
 US.Anr^Y. 
 
 F.A.f^.C.B: 
 
Railroads. 221) 
 
 1.5 in. X 7 in. x 12 ft., joined together in three sections (2 for the 
 outside, "A," "A;" and 3 for the middle one, "B"); by wooden 
 strips "C," 1 in. thick, and 2 in. wide, bolted to the upper surfaces, 
 1 ft. between centers; these strips also serve as foot holds. Along 
 the middle of the outside boards extends a side rail, "D," 3 in. x 
 3 in. held firmly by the iron straps, "E," ^ in. x 2 in. On the out- 
 side of each side rail are 3 sockets "P,'' for standards "G" 3 ft. 
 high, along the tops of which are to be stretched ropes or chains 
 from which canvas or blankets are hung. On the under side of 
 each section 3 ft. apart are bolted iron cleats, "H,*' 0.5 in. x 2 in., 
 beginning at 18 in. from the ends. On the ends of each section are 
 bolted iron claws, "K," for catching the car floor or door slide, to 
 prevent slipping when in position for use. The three sections are 
 held together for use by 4 iron tie bars, "L," 0.5 in. x 2 in. which 
 are placed under the cleats "H," and the whole firmly keyed as 
 shown. This form of ramp may be made longer or shorter, nar- 
 rower or broader, as desired. By taking out the standards it 
 may be hung on the side of a car between a door and end. It 
 is easily taken apart and transported in a wagon, and as easily 
 put together when needed. It is designed to combine both 
 strength and liglitness. It weighs about 400 lbs. complete. 
 
 31)8. — Disabling and destroying railroads. Under the 
 head of disabling will be mentioned means, the effects of which 
 will only temporarily interrupt traffic, can be easily repaired, but 
 will cause delays. 
 
 399. — Under destroying, such as are more serious in their 
 effects: either causing extensive repairs or a change of route to 
 avoid them. 
 
 400. — The disabling of railroads will usually be done by raid- 
 ing parties of cavalry, while the destroying of them may be done 
 by such parties or specially detailed troops trained for such 
 service. 
 
 401 . — It must be understood that no railroad is to be destroyed 
 except upon the orders of the officer commanding in the field. 
 If otherwise, and it should be taken from the enemy, the dam- 
 age done might seriously embarrass future operations. Before 
 ordering any destruction the quesiton will arise^" Is destruction 
 absolutely necessary ?" "Will it be of no further use and is every 
 hope of regaining it gone ?" " Are the advantages to be gained 
 sufficient to compensate for the damage that will be done ?" All 
 
II.'JO Kailkoads. 
 
 the attending circumstances should be carefully considered, 
 especially if in one's own country. The choice of points for de- 
 struction and the most effective means are subjects for study. It 
 is useless to destroy anything that will not seriously embarrass 
 traffic. 
 
 402. — A railroad may be disabled by removing rails at 
 various intervals, then destroying or hiding them ; or, if a large 
 number of men are at hand, select a high embankment, line the 
 men along on one side of the track, disconnect the rails at each 
 end of the line of men, then, at a signal, they raise the track on 
 edge and let rails and ties together go over the embankment. 
 Thus treated, rails and ties must be separated before being re- 
 placed. An improvised wrench for removing nuts on fish plates 
 is a bolt with two nuts on it, just far enough apart to grasp the 
 nut to be removed. (PI. 52, Fig. 5.) If time is an object, remove 
 outside rails on a curve, or disconnect a joint on each side and 
 throw them as a switch to derail the train either on an embank- 
 ment or in a cut, or use explosives as described in Chap. XX. 
 
 By laying rails across a pile of burning ties until red hot in the 
 middle they may be easily bent around a tree or telegraph pole ; 
 they may be twisted by heating, as above, then using bars or pick 
 axes placed in the holes in each end and working in opposite 
 directions. 
 
 They may be torn from the ties and twisted cold by using Gen. 
 Haupt's "U "shaped rail twister, shown on PI. 40, Fig. 8. Ten 
 men with two twisters, two axes, two stout pieces of rope 35 ft. 
 long, can tear up and twist a rail in 5 minutes. The junctions of 
 lines are important points to attack to disable a track. 
 
 Water tanks may be rendered useless for a time by breaking 
 holes in them, removing pistons from pumps, etc. Fuel, ties, and 
 small bridges may be burned. Engines may be disabled by burn- 
 ing out the flues, removing or breaking different parts of the ma- 
 chinery, tilling suction pipes of pumps with waste, etc. Cars may 
 be disabled by removing couplers, axle boxes, breaking or remov- 
 ing trucks, etc. The use of mines under the track, so arranged 
 as to be exploded by the passing of trains, is an effective method 
 of interrupting traffic and shaking the morale of troops being 
 transported. 
 
 403. — To destroy a railroad, if time is sufficient, remove roll- 
 ing stock, rails, etc., to the rear. Otherwise, destroy large bridges, 
 
Railroads. 231 
 
 if of wood, by burning, using oil if it can be obtained, or by explo- 
 sives, as in Chapter XX. If of iron, steel, or masonry, by ex- 
 plosives, as in Chapter XX. If there are tunnels on the line, 
 select longest ones and blow them in at as many points as possi- 
 ble, or cause two wild trains to collide in the middle, afterwards 
 blowing in the ends. Those with sandy soil are the best. Deep 
 cuttings with retaining walls may be filled in by use of explo- 
 sives. If trees, poles, wires, etc., can be mixed in — so much the 
 better. Blow up tanks and engines, burn all fuel, cars, repair 
 supplies, etc. Fire a cannon ball through engines. 
 
 404.— The repair of railroads will best be accomplished 
 by a construction corps having some of the elements of perma- 
 nency in its organization; or, at least, by small squads of exper- 
 ienced men to which others could be added by temporary detail, 
 whenever active operations require such increase. They should 
 be established as near to where their services may be needed as 
 possible. 
 
 405. — Bridges should, in the beginning, be classified and 
 numbered, so that a single reference to the class and number will 
 give complete information as to its character, dimensions, etc. At 
 designated points will be kept on hand, already prepared for put- 
 ting in bridge, suitable materials for the repair of each class. 
 This was done by the Union Army from 1861 to 1865, so that, 
 when word was received that a certain bridge had been destroyed, 
 by a reference to the class and number the reconstruction corps 
 started out carrying with it just what was needed to repair the 
 bridge. Even complete trusses for the larger class of bridges 
 were prepared and kept ready for use. 
 
 406. — Tunnels and cuts which have been filled up can gener- 
 ally be cleared only from the two ends. 
 
 40T. — Rails, fish plates, spikes, ties, etc., will be kept in store 
 at secure places, for repairing any portions of destroyed track. 
 Rails which have been simply bent can be straightened by 
 various means. Gen. Haupt'S method was as follows: Two 
 ties were placed on the ground, across these two more ties and on 
 top a single tie which was cut across one-half the depth of the 
 rail to receive it and prevent it turning. Weight was applied at 
 the two ends of the rail by men bearing down on poles placed 
 thereon. The rail being moved back and forth until straightened, 
 requiring from 4 to 5 minutes. Rails which had been heated and 
 
232 Railkoads. 
 
 bent to a very sharp angle required more time, necessitating re- 
 heating and hammering until straightened. For this purpose, at 
 special points were prepared furnaces consisting of two parallel 
 walls of brick, stone or clay, with a kind of grate. The straight- 
 ening table consisted of a large, square timber as long as a rail, on 
 which were securely fastened three rails, as in PI. 52, Fig. 9 on 
 which the heated rail was laid and hammered until straightened. 
 Twisted rails require re-rolling before they can be again used. 
 
PLATE 54. 
 
CHAPTER XIX.— Telegrapli and Teleplioiie I^iiies. 
 
 408.— In order that telegraphic messages may be sent from 
 one point to another, it is necessary that there be a continuous 
 metallic conductor from the first to the second point and that this 
 conductor be insulated from contact with the ground or with any- 
 thing leading to the ground. The conductor used in construct- 
 ing permanent lines is of galvanized iron wire, generally of size 
 No. 9. In military lines it is generally somewhat smaller on ac- 
 count of the weight. The wire is carried on poles and tied to glass 
 insulators which are attached to the poles. 
 
 409. — Poles should be not less than 22 feet in length nor 
 less than 7 and 5 inches in diameter at the larger and smaller 
 ends respectively and should be stripped of bark and pointed at 
 the upper end. The holes for poles should be not less than | the 
 length of the pole in depth. The poles should be raised as shown 
 in PI. 54, Fig. 1 and held vertically while the excavated earth is 
 thoroughly tamped in from bottom to top ; after the hole is com- 
 pletely filled the earth should be made into a small mound so as 
 to shed water. 
 
 410. — When the brackets are attached to the pole directly, a 
 seat should be cut in the pole with a hatchet and the bracket 
 should be nailed on, using 1 twenty-penny and 1 forty-penny nail. 
 Where the poles are intended to carry several wires, cross-arms 
 are bolted to the poles, fitting into seats cut for them. The arms 
 carry brackets not less than 15 in. apart. The arms should not 
 be less than 20 in. from one another. Not less than 25 poles to 
 the mile should be used, and in special cases the number may be 
 increased to 30. 
 
 411. — Every 5th pole should be protected from lightning dis- 
 charges by having a piece of line wire run from about 6 in. above 
 the top of the pole to the ground. This wire must he so arranged 
 
2^56 TeLFXIR APU AND TELEPHONE LiNES. 
 
 that it cannot come in contact with the line wire should that be- 
 come unfastened. Poles should be vertical except when neces- 
 sary to incline them to resist strains, when they will be set at a 
 slight inclination, in such manner that the component of the 
 strain in the direction of the length of pole will tend to press it 
 into the ground. Where exposed to great strains, or to contin- 
 uously high winds, it may be necessary to guy the poles: this is 
 done with stays consisting of two or more line wires twisted to- 
 gether and fastened near the top of the pole, the ground end being 
 attached to a section of a pole or timber suitably anchored in the 
 ground, as shown in Fig. 2. Where possible, the line of poles 
 should be run on one side of the road and far enough from it to 
 be safe from accidental damage by passing wagons. Where roads 
 have to be crossed, the wire should be carried over on high poles 
 so as to clear any possible wagon load. 
 
 412. — The insulators in common use in this country are of 
 glass and of the form shown in Fig. 3. The one shown in Fig. 4 
 is preferable, as it is not so liable to cause leaks on account of 
 moisture accumulating and forming a connecting film to the 
 bracket and from that to the pole. 
 
 413. — The wire is attached to the insulators by pieces of wire 
 called ties. These are generally of the same wire as the line. 
 They are annealed and formed on an insulator and cut long enough 
 to embrace the insulator and project 3 or 4 inches beyond the line 
 wire. 
 
 414. — To liaug tlie wire. The wire is carried up to the 
 top of the pole and the lineman places a tie on the insulator, the 
 line wire against the insulator above the tie wire, and bends the 
 ends of the tie wire upward so as to sustain the line wire. The 
 line w^re is then strained by the lineman, either by means of 
 hand power or by use of the wagon carrying the reel. When the 
 ine wire is stretched so that it sags but about 1}4 ft. in 70 yds. 
 the tie wire is wrapped around it about one and a half times, finish- 
 ing with the ends of the tie wire pointing towards the insulator ; 
 this secures the line and completes the work. (Fig. 5.) 
 
 415. — 111 ojjeii coiiiitry the line wire is strung on the in- 
 sulator on the side towards the pole, so that, if it becomes acci- 
 dentally undone, the wire will not drop. If in timbered country, 
 then hang it on the side from the pole, so that when trees, etc., 
 fall against the wire it will simply tear it away from the insulator, 
 
Telegraph and Telephone Lines. 237 
 
 but will not break the line wire. When necessary to hang the 
 wire on trees, a regular tree insulator should be used, and in de- 
 fault of this, the tie shown in Fig. 6 may be used, the ends being 
 wound loosely so as to allow of an easy lateral motion to accom- 
 modate the swing of the tree. The poles should be numbered at 
 each mile so as to aid linemen to report location of breaks and 
 repairs. 
 
 Streams are crossed by hanging the wires on strong, high sup- 
 ports, taking care not to strain the wire so much as to cause it to 
 break. 
 
 . 416. — The description of instruments and batteries, their con- 
 nections and care, will be found in the Manual published by the 
 Signal Service of the Army. 
 
 417. — Joints. Where wires have to be joined to preserve the 
 continuity of the metallic circuit, the best joint is the American 
 twist joint. To make this, clean the wires for a length of 5 or 6 
 inches, make a right angle-bend in each wire about 4 inches from 
 the end, now join the wires so that the ends project on different 
 sides and clamp both wires with a hand vise, then with a splicing 
 iron turn the ends around the line wire, making the turns as close 
 as possible; after the entire end is turned around the line wire, 
 cut oif the projecting end and dip the joint into melted solder ; 
 this protects the joint against rusting. The details of this joint- 
 making are shown in Figs. 7 and 8. 
 
 418. — Military lines are generally of the kind designated as 
 flying lines, i. e., they are intended to accompany the army in the 
 field, are constructed quickly for temporary use, and are as quickly 
 dismantled and taken up. The poles used are small poles called 
 lances, each about 2J in. in diameter and 17 ft. in length, placed 2 
 ft. in the ground, and run about 40 to the mile. The batteries, 
 line lances, and instruments are carried in wagons which accom- 
 pany the army. A detailed description of the telegraph with 
 directions how to erect and dismantle is found in the Manual of 
 Signals for the U. S. Army. The ordinary telephone receiver 
 (with magneto call bell) is used on the military lines; but for the 
 use of outposts, reconnoiterers, and scouts, a special form of tele- 
 phone cart and wire has been adopted, the following description 
 of which is taken from the Report • of the Chief Signal Officer of 
 the Army, 1892: 
 
238 Telegkaph and Telephone Lines. 
 
 *'The frame of this cart is constructed of bicycle tubing, and 30 
 in. bicycle wheels with heavy cushion rubber tires are used. The 
 cart is fitted with an automatic spooling device for reeling up the 
 outpost cable. This device was made by F. S. Cahill & Co., and 
 is a success. The cart carries 5 reels of cable and 1 reel knapsack 
 for use in places where the cart cannot penetrate owing to under- 
 brush, etc. As the extreme width of the cart, measured at the 
 wheels, is only 26 in., it can follow any ordinary path through 
 underbrush. The weight of the cart complete with spooling de- 
 vice, but without the reels, is only 53 pounds ; when loaded with 
 reels and reel knapsack the total weight is 157 pounds. The cart 
 is well balanced upon its axle by a device which permits the 
 point of support to be changed to balance the cart, as the distri- 
 bution of the weight is changed by the cable being run out. In 
 connection with the reel cart a telephone kit is used, and by at- 
 taching the double connector of the kit to one on the frame of 
 the cart the telephone is kept in circuit and conversation can be 
 kept up with the home station. The cart with its load can be 
 easily drawn by one man, and by its use it will be possible to con- 
 nect outposts with the main guard, or brigade with regimental 
 headquarters, or brigade with division headquarters, in a few 
 minutes of time. The experience of the English in Egypt has 
 proved the value of the field cable line in action, as by means of 
 these lines the Commanding General was kept in communication 
 with different divisions of troops and with those actually engaged 
 in the firing line. It is proposed to fit shafts to the cart so that a 
 horse can be harnessed to it, thus securing great rapidity in run- 
 ning out the cable. The cart carries 1§ miles of cable which can 
 be paid out as fast as a man moves with the cart, and by means of 
 the reeling apparatus and spooling device can be recovered at the 
 rate of 4 miles per hour, or as rapidly as a man can walk with the 
 cart." 
 
 419. — Faults are generally of three kinds — breaks or discon- 
 nections, leaks or escapes, and crosses or contacts. 
 
 Breaks occur when the metallic circle is broken or cut so that 
 either the disconnection is complete, as when entirely severed ; or 
 incomplete, when partially cut or where a joint is rusted so much 
 as to increase the conductive resistance. In these cases the in- 
 struments will work weakly or fail entirely. 
 
Telegraph and Telephone Lines. 239 
 
 [Leaks, or escapes. Where the insulation is destroyed or is 
 defective or where a wire comes in contact with a conductor to 
 the earth or with the earth itself, a portion of the current leaks or 
 escapes. When the wire is swinging the leak will be intermittent ; 
 when constant leakage is going on the instruments will work 
 weakly ; failing altogether when the leak becomes complete, then 
 it is called a ground. 
 
 A cross occurs when two wires, each carrying currents, are 
 brought into contact; thus the instruments on one line will inter- 
 fere with the workings of those on the other. Generally occurs 
 from parallel wires being swung over one another by the wind, or 
 having a good conductor fall so as to touch both wires. 
 
 420. — Telegraph lines should never be damaged or destroyed, 
 except in obedience to direct orders. Faults may be made by con- 
 necting the wires together with small wire (this makes a bad 
 cross), or they may be connected with the lightning rods on the 
 poles, thus running them to the ground. 
 
 When an office is taken, the instruments should all be discon- 
 nected and destroyed or taken away ; the ends of the wires should 
 be tied together. The batteries, if any, should be disconnected. 
 To destroy the line, cut down the poles and burn them and cut 
 the wire into small lengths. Subaqueous lines should be brought 
 up with a grapnel and a piece cut out and cut into small pieces 
 and thrown back into the water. Subterranean lines are gener- 
 ally laid in conduits, and at regular intervals man-holes are built 
 to allow of repairs ; the line may be detected by these man-holes, 
 the conduit destroyed, and the cables disconnected. 
 
CHAPTEH XX.— Demolitions. 
 
 421.— In military practice, demolitions must be made with the 
 least possible expenditure of time and explosive. At the same 
 time, a charge which in itself seems large for a particular case 
 may prove economical, in that it errs on the right side and a repe- 
 tition of the work is not made necessary. 
 
 Military engineers have to destroy bridges, houses, walls, etc., 
 render roads impassable, fell trees, and place mines. In all these 
 operations, high explosives are generally used, on account of their 
 portability, ease of handling, and great destructive effect. In 
 some cases, ordinary gunpowder is available, and may be used to 
 advantage if time allows of its proper placing and tamping. Gun- 
 cotton, however, is the standard explosive for military work, and 
 all formulas will be calculated for its use. 
 
 422. — (iuii cotton, as made at the U. S. Naval Torpedo Sta- 
 tion, is in blocks about 3 in. square and 2 in. thick, each block be- 
 ing i^erforated to allow the insertion of the primer, and when dry 
 the blocks weigh 10 oz. When necessary to use blocks of smaller 
 dimensions, the large ones may be cut, when wet, by using a saw 
 or sharp knife, care being taken to place the block to be cut be- 
 tween two boards, so that it will not flake or crack during the 
 operation. Wet guncotton can be detonated by means of a primer 
 of dry guncotton. Guncotton will absorb about 30% of its weight 
 of water, and, when in this condition, it is comparatively safe, as 
 it can only be ignited by fire and is difficult of detonation. When 
 packed for transportation, the blocks are placed, while wet, in a 
 tin can, and sealed hermetically; or, the can is left so that the 
 water can be replaced when it has evaporated. 
 
 423.— When both are well tamped, guncotton has an explo- 
 sive force from 2 to 2^^ times as great as gunpowder, but when no 
 tamping is used it has a force 4 times as great. When guncotton 
 
PLATE 55. 
 
 Figu:re 1. 
 
 Figure 2 . 
 
 
 ^ 
 
 Figure 
 
 Figure 4. Figure 
 
 6- 
 
 Figure' 
 8 
 
Demolitions. 243 
 
 is needed for use as primers, a sufficient quantity is taken from 
 the wet case, placed in the sun, and allowed to dry. In operations 
 in the field, a small quantity of dry guncotton should be carried, 
 so as not to waste time in drying the primers. Wet guncotton 
 detonates with much greater force than dry, but it is necessary 
 that this action be set up by the detonation of a dry block placed 
 in intimate contact with the wet charge. The manner of firing 
 guncotton is as follows:— 
 
 After placing the explosive in as close contact as possible with 
 the object to be destroyed, and seeing that the blocks composing the 
 charge are in intimate contact, the detonator is placed in the hole 
 in the center of the dry primer block and the fuse is lit or the 
 current sent through the wire, as the case may be. The detona- 
 tion of the dry primer will set up detonation in all the blocks and 
 the detonation will be simultaneous throughout the entire mass. 
 When used in holes, guncotton should be dry, as wet guncotton is 
 difficult to detonate under such circumstances. 
 
 424. — Detonators. The detonators are copper tubes, about 
 3^ in. in diameter, closed at one end, and partially filled with a 
 fulminate composition which is ignited either by a fuse or by 
 electricity. The ordinary blasting cap (PI. 55, Pig. 1), or detona- 
 tor, is intended for use with a fuse, and is designated as single, 
 double, or triple force, according to the amount of fulminate com- 
 position used. In all military work, it is better to use the triple 
 or higher force caps, as their action is sure, even on comparatively 
 low explosives.* 
 
 425. — The fuse generally used in this country to ignite these 
 detonators or caps is that made by Ensign, Bickford & Co., Sims- 
 bury, Conn., the grade known as "double taped'' being the best for 
 general work when the fuse is not exposed to prolonged immer- 
 sion in water or damp ground. When it is necessary to use fuse 
 for submarine explosives, the waterproof fuse should be used. 
 The rate of burning of the fuse should be found by experiment 
 before using. This is done by taking several pieces, 1 ft. long, 
 and finding the average rate of burning and taking this as the 
 standard. The rate at which this fuse is intended to burn is 3 ft. 
 per minute, but it varies somewhat, so that when great nicety is 
 required it should be tested as above. 
 
 * Single force caps contain 3 grs., double force caps 6 grs., and triple force caps 9 grs. 
 of fulminate of mercury. 
 
"24.1 Demolitions. 
 
 42G. — To prepare a fuse and detonator for use, cut the fuse to 
 the length required, leaving a square end ; insert this end in the 
 detonator until it rests against the fulminate, taking care not to 
 scratch the fulminate. Then crimp the copper against the fuse 
 so as to hold it firmly : this is done by means of pincers made for 
 the purpose ; or, in case these are not available, any pincers or 
 the edge of a dull knife may be used, being careful not to crimp 
 on the portion of the cap containing the fulminate. When ready 
 to fire, insert the detonator in the hole in the center of the prim- 
 ing block, secure it by tying with wire or twine, and, when ready, 
 light the fuse. 
 
 To ignite powder, the fuse alone is used, being placed so that 
 the end is well centered in the mass of the powder and so secured 
 that it cannot pull out. 
 
 427. — Electrical fuses and detonators are constructed 
 so that ignition takes place upon the passage of a current of suf- 
 ficient intensity through a platinum wire, around which is wrapped 
 some fleecy guncotton or other inflammable material which is ignited 
 by the platinum wire being heated to redness when the current is 
 turned through the primer, this ignites the rest of the composition 
 which causes detonation or explosion as the case may be. 
 
 Two forms are shown — the commercial (PI. 55, Fig. 2) and the 
 service (PI. 57, Fig. 10.) The commercial is so constructed that 
 it can be used with maximum effect only in detonating compounds; 
 while the service fuse, by removal of the copper cap containing 
 the fulminate, is converted into a simple electric fuse and maybe 
 used to ignite gunpowder mines. The current of electricity is 
 generated by means of a battery consisting of several cells or by 
 electrical machines of various forms. The means now generally 
 used, and the one that gives surest results, is the magneto ma- 
 chine. On account of its portability and compactness, and be- 
 cause of its simplicity, the *'Laflin & Rand Exploder, No. 3," is 
 recommended for all work when electricity is to be used as the 
 igniting agent. (Fig. 3.) 
 
 428.— When more than 5 fuses are to be fired in one series, it 
 is advisable to use a larger machine of the same construction. In 
 favorable cases, the machine in question will ignite as high as 12 
 charges, but, in military work, it is best to leave nothing to 
 chance, and the limit stated above is a good one. The machine 
 is cased in wood and its dimensions are 13 x 8 x 5i in., and 
 

PLATE 56. 
 
 FIGl 
 
 FIG 4. 
 
 FIG, 6 
 
 I 
 
 I 
 
 f   
 
 
 
 
 -ll. 
 
 
 
 tv 
 
 v!s-sr3=3: 
 
Demolitions. 247 
 
 weighs 18 lbs. The connecting wires are attached to two brass 
 binding posts, which are found on the top of the box. The handle 
 on top of the box is lifted, withdrawing the ratchet bar to its full 
 length, and, when the time arrives to fire the charge, the bar is 
 pushed vertically downwards; moving slowly for the first inch or 
 two, then by a swift, but even pressure till the lower end is 
 stopped at the bottom of the box. 
 
 Ill all connection of wires, at least 2 in. of each wire 
 must be cleaned bright and well wrapped around one another, 
 as shown in PI. 55, Fig. 4 ; under no circumstances simply hook 
 wires together. 
 
 429. — After wires are joined, the joint should be insulated by 
 winding rubber tape, or wide rubber bands, around so as to over- 
 lap the next previous turn. When water has to be encountered, 
 wrap with rag or a strip of linen and cover with tar ; or, use rub- 
 ber tube as shown : the tube in this case is placed on one of the 
 wires, and, when the joint is made, is pulled over it and tied 
 tightly to the wires on either side of the joint. (PL 57, Fig. 9.) 
 
 Where dynamite is used, a hole is made for the detonator in 
 the end of the cartridge with a sharp stick or lead pencil and the 
 detonator with fuse or wire attached is inserted ; the envelope is 
 then tied around the fuse, so that the detonator cannot become 
 detached from the cartridge, care being taken to place the detona- 
 tor in cartridge only about % its length, so that the charge may 
 not be ignited by sparks from the fuse before the detonator is ex- 
 ploded, and all is ready. When electricity is used, push the deto- 
 nator in its full length and take two half hitches, with wires, about 
 the cartridge, so as to hold every thing in place. (PI. 56, Fig. 1.) 
 
 In all cases, where more than one package or piece of guncotton 
 or dynamite is used, the closest contact possible should be made 
 between the explosive and the material to be destroyed, and also 
 between the different pieces of explosive. In all cases wherever 
 the magneto machine is to be used, be careful not to connect the 
 wires with machine till every one is at a safe distance from the 
 place of explosion. When more than one charge is fired, the 
 wires leading to the several charges should be connected as shown 
 in PI. 57, Fig. 6. 
 
 430.— To fell trees, bore a hole at the height desired, in- 
 sert the charge, and Hre, care being taken that the center of the 
 charge is about the center of the tree. If the charge be of a 
 
218 iJKMof.i'noxs. 
 
 length equal to or less than the dianioter of the tree, then the 
 hole may be bored directly through ; but if greater, then two or 
 three holes, intersecting at the center, must be bored. — Charge in 
 ounces may be calculated by the formula c =r 6d^, in which c is 
 charge in ounces and d the diameter in feet. To make the tree 
 fall in a given direction, tie a rope to that side and pull. When 
 time is not available to bore a hole, make a necklace and bind 
 around tree. — Charge in ounces = iSd"^. When impracticable to 
 make necklace, place charge in a bag, or support by stakes, so 
 that all the explosive is against one side of tree, and fire. — Charge 
 in ounces = GOd^. In this case, the tree will generally fall 
 towards the side of explosive. This method of felling trees is 
 more expensive than with the axe, and is not resorted to except 
 when time is not available for the slower method. It is not ad- 
 visable to use either of the last two methods when it can be 
 avoided, as there is great waste of explosive. (PL 55, Figs. 5, 6, 7 
 and 8.) 
 
 431. — To destroy bri(lg:c timbers, if rectangular, the 
 charge is placed across the whole width of the beam; 10 ozs. will 
 destroy a beam 12" high and 6" thick. The charges for other di- 
 mensions vary with the height and square of the thickness. Charges 
 may be calculated by the formula c=3 li T ^ in which c equals 
 the charge in lbs., h the height, and T equals thickness in ft. If 
 the timbers are circular or square, the charge will be same as for 
 trees, taking the diameter of the round and the side of the square 
 one as d in the formula given. (PL 56, Pig. 2.) 
 
 432.— When high explosives are not on hand, the bridge tor- 
 pedo used in the war of the rebellion may be used. It consists of 
 a bolt 8 or 9 in. in length, surrounded by a tin cylinder 2 in. in 
 diameter and filled with powder. The ends of the cylinder are 
 closed by iron washers, and a fuse placed in one end. To use this 
 torpedo, a hole 2| in. in diameter is bored in the timber and the 
 torpedo inserted having its center at the center of the timber; it 
 is then exploded by means of a fuse. If necessary, two may be 
 placed in holes bored at right angles to each other. (Fig. 4.) 
 
 433.^Palisading up to 10 in. in thickness takes 4 lbs. of 
 guncotton for each ft. in length to be destroyed. 
 
 434. — For stockades, when the timbers are close together — 
 4 lbs. of guncotton per foot in length. 
 
 If the timbers are squared, the blocks of cotton may be fastened 
 
Demolitions. 241) 
 
 to a thin board and placed against the foot of the stockade, but if 
 of rough logs, tie the blocks together so that they may adapt 
 themselves to the form of the timbers. 
 
 When stockades are double, and separated by a distance of one 
 yard -25 lbs. of guncotton per foot in length or one charge of 80 
 lbs. may be placed. 
 
 Railway iron stockades are breached by 7 lbs. per foot in 
 length. 
 
 In all cases, distribute the charge so as to cover the length de 
 sired to be breached. 
 
 435. — To cut steel rails, use one block of guncotton, 
 weight, 10 ozs., tie the block against the web of the rail with wire 
 or twine, and, if possible, tamp well with earthy and explode. 
 (Fig. 3.) 
 
 To blow a piece of some length out of a rail, arrange two 
 charges of 10 oz. as shown above, placing one on each side of the 
 rail at a distance apart of 5 or 6 ft.; these should be exploded 
 by use of a magneto machine so that the action may be simul- 
 taneous in both charges; the section will be blown out and 
 turned on its center, making a large opening. (Fig. 5.) 
 
 436.— Switch points maybe destroyed by lodging a block 
 of cotton between the outer rail and the pivot end of the switch 
 point, being careful to tamp as completely as possible, ("A" PL 
 51, Fig. 11.) In the case of frogs, one 10 oz. block, placed in the 
 angle of the frog, will destroy the point and render it useless. 
 (^'A/'Pl. 52, Fig, 1.) 
 
 437. To destroy a wooden truss bridge, blow away 
 the main brace of the panel nearest to an abutment or pier; it is 
 really necessary to blow only one side down but it is better to be 
 sure and destroy both sides. If the bridge has an arch of wood 
 besides the truss then destroy the arch on each side. If time is 
 available, the bridge may be burned; to do this, collect brush, 
 etc., and, if possible, place it under one end so as to burn it oif 
 and cause the span to drop, but if not possible, build the fire in 
 the center of the span; it will burn through and cause rupture in 
 the center. 
 
 In all cases attack span over the deepest water. 
 
 438. — To cut wrouglit iron plates the charge of gun- 
 cotton in pounds is found from the formula c =1.5wt2 in which 
 c equals charge, w the width of plate to be cut in feet and t the 
 
250 Demolitions. 
 
 thickness in inches. The charge must be placed entirely across 
 the plate to be cut. 
 
 439.— To calculate the charge necessary to rupture an iron, 
 bridge beam or girder, calculate the charge for each separate cross 
 section to be cut and add the results; the sum will be the charge 
 required. The charge is most conveniently placed on the side of 
 the beam, reaching entirely across and bound on with wire, the 
 I^rimer being in the center of the charge. If possible, a board 
 should be tied over the whole charge and earth tamped in around 
 it. When time is not available for the placing of the charge as 
 descrihoil above, then it may be placed on top of the beam or on 
 the liange, the charge being calculated by the above formula. In 
 demolishing iron girder bridges the charge is applied as described 
 for iron girders. (Figs. 6 and 7.) When the girder bridges are only 
 short ones up to 20 ft. in length, they may be overturned by levers 
 and thrown down from the abutment. 
 
 440. When it is necessary to destroy truss bridges the most 
 lavoiahlr place for the charge is at the center of the span on the 
 lo\v(u- cliord. When the bridge is of the variety known as a deck 
 bi-idgc. the charge should be jjlaccd on the top member, the 
 amount necessary being calculated as shown above. When the 
 lower or tension member is composed of eye bars the charge 
 should be placed between alternate pairs of eye bars as near to 
 the coupling pin as possible. (PI. 57, Fig. 1.) When bridges are 
 supported by iron or wood piers, it is sometimes possible to des- 
 troy the piers and thus bring down the entire structure. The 
 charges may be calculated by formulas for iron or wood as the 
 case may be. It is best to destroy the supports on both sides of 
 the pier as this will infallibly bring down the entire structure. 
 
 441 . 1 11 (lestroyiiig siisi)eiisic>ii ll)ri(lges, blow down the 
 towers below the saddle, excavate and blow out one of the anchor- 
 ages or cut the cable with guncotton. The charge for bridge 
 cables is calculated as for cutting iron plates, but the charge must 
 be very carefully placed so as to be in close contact with the cable. 
 If the cables are made of plates, the plates may be cut tcith 
 cotton, as in the case of eye bars, cited above. Where bridges of 
 iron or wood are supported by masonry piers, the piers may be de- 
 stroyed by charges calculated by the formulas given below. 
 
 442." To blow down a Avail, the charge should be placed 
 against the bottom as close to the wall as possible, and if possible, 
 
PLATE 57. 
 
Demolitions. 253 
 
 should be tamped. If time allows, a channel should be cut in the ^ 
 wall at the seat of the charge. When untamped, c =^^t2 where c /^ 
 equals charge in pounds, w width of wall to be breached, and t 
 thickness, w and t being in feet; and when tamped with earth equal 
 in thickness to the wall, half the above charge may be used. 
 (Pig. 2.) 
 
 44:3. — Bridge piers in masonry may be destroyed by charge of 
 I Wt^ poll running foot . This means excessive expenditure of ex- 
 plosive and would not be used against short, thick piers. In case 
 one has to be destroyed, place small charges in chambers exca- 
 vated as deep as possible in the masonry, and explode all simul- 
 taneously; calculate charges as for walls. Masonry bridges 
 should be attacked at the haunches; if that is not possible, then 
 blow in the crown. When attacking the crown, place explosive 
 in trenches clear across the bridge, and, if possible, on the ma- 
 sonry of the arch itself; better use two trenches, each placed, 
 from the middle of the bridge, a distance equal to | the width to 
 be breached at the crown or arch; calculate charge for each 
 trench clear across the roadway. If haunches are attacked, dig 
 down as far as desired and place charge clear across on back of 
 masonry; charge f Wt^ if untamped, and half of this if tamped. 
 (Fig. 3.) 
 
 444. — Gates may be blown in with 50 lbs. of guncotton ex- 
 ploded in one charge. The charge is hung against the center of 
 gate by means of a sharpened pick or on a nail. This charge is 
 large, but gates will generally be strengthened in some man- 
 ner on the inside. (Fig. 4.) 
 
 445. — Houses may be blown down or shattered by placing 
 charges in the center of the floor and closing all outlets such as 
 doors, windows, etc. Charge according to the size, 20 lbs. being 
 sufficient for small houses. 
 
 446. — Tunnels may be destroyed by placing charges back of 
 the masonry at the spring of the arch. If possible the charge 
 should be placed in a chamber excavated behind the arch and 
 well tamped. Tunnels should be blow^n in at several places, so 
 as to render it impossible to repair them in a short time. Charges 
 as for bridge arches. (Fig. 8.) 
 
 447. — One and one-half pounds guncotton detonated on the 
 chase will disable field or siege guns; the damage is more consid- 
 erable when the charge is tamped. If not damaged by the first 
 
 ^ 
 
254 Demolitions. 
 
 explosion, double the charge and explode in the same place. 
 Heavy fortress guns may be disabled by destroying their car- 
 riages by the use of guncotton. Wherever gunpowder is used as 
 an explosive it should be enclosed in stout bags, preferably two, 
 and the outer one well tarred. This is to protect from accidental 
 explosion set up by sparks from the fuse. (Fig. 5.) 
 
 448. — The following table gives in a concise form all informa- 
 tion necessary for the use of guncotton and gunpowder. The 
 table shows approximately the value of the different high 
 explosives as compared with guncotton. 
 
 Note: — Charges are in lbs.; B and T are in feet ; t is in inches. 
 
 B is length of breach to be made ; T or t is thickness of object 
 to be demolished. 
 
 Gunpowder is assumed to be roughly tamped with sand-bags. 
 Guncotton is untamped. If the guncotton is tamped, the charges 
 may be reduced by about one-half. 
 
 Charge of guncotton must be equal in length to the breach 
 which is to be made. 
 
Hasty Demolitions. 
 
 255 
 
 Object attacked 
 
 Gunpowder 
 
 Guncotton 
 
 Remarks 
 
 Brick arch "^ 
 
 r 
 
 |BT2 
 
 2 lbs. per 
 
 The length of 
 breach, B, should 
 
 Brick wall, 2 ft. or 
 
 less 
 
 Brick wall over 2 ft. 
 
 thick 
 
 Brick piers ^ 
 
 |BT2 < 
 
 foot run 
 
 |BT2 
 |BT2 
 
 ^not be less than the 
 height of the wall 
 to be brought down. 
 
 Hard wood (e. g., teak, 
 
 40 to 100 
 
 ^Lm^ 
 
 In a concentrated 
 
 oak, elm), in any 
 
 lbs. for 
 
 -b^rr"^ 
 
 charge, or for trees 
 
 form, whether 
 
 stockade 
 
 
 not over 12 in. diame- 
 
 stockade, palisade, 
 
 
 
 ter, in a necklace. 
 
 single timbers. 
 
 
 ^nr^ 
 
 In auger hole, when 
 
 trees, etc 
 
 
 the timber is not per- 
 fectly round, T = the 
 
 
 Soft wood 
 
 Half the 
 for hard 
 
 charges 
 wood 
 
 smaller axis. 
 
 
 Breastwork of hori- 
 
 60 to 80 
 
 4 lbs. per 
 
 
 zontal balks, or 
 
 lbs. per 
 
 foot 
 
 
 earth, between 
 
 5 ft. 
 
 
 
 sleepers, up to 3 ft. 
 
 
 
 
 6 in. thick 
 
 
 7 lbs. per 
 
 
 Heavy rail stockade . . 
 
 
 
 foot 
 
 
 Fortress gate 
 
 200 lbs. 
 
 50 lbs. 
 
 
 Iron plate 
 
 
 1 Bt2 
 
 In this case only, t 
 is in inches. 
 
 
 
 2 
 
 Field or Siege guns. . 
 
 
 \\ lbs. 
 
 On chase near muz- 
 zle. 
 
 Heavier guns 
 
 
 4 lbs. 
 
 In bottom of bore, 
 tamped with water or 
 
 
 
 
 
 
 sand. 
 
 First-class iron rail.. . 
 
 
 1 lbs. 
 
 Touching web of 
 rail and near a chair. 
 
 " " steel rail . . 
 
 
 4 ozs. 
 
 Four rails placed 
 round the charge will 
 be cut simultaneously 
 by it. 
 
25G Demolitions. 
 
 Approximate Relative Strength of Some op the High 
 Explosives. 
 
 Exijlosive gelatine 128.3 
 
 Nitroglycerine 120.3 
 
 Guncotton 100 
 
 Dynamite, No. 1,%% Nitro glycciino 07.8 
 
 Rack-a-Rock 74.2 
 
 Dynamite, 50% 72.7 
 
 449.— Destruction of Obstacles. Wire entanglements 
 
 may be destroyed by cutting with wire nippers, or, if they are not 
 at hand, then the ordinary hand axe will do, taking care to cut 
 against the picket. 
 
 450. — Abatis is very difficult to destroy and cannot be re- 
 moved while fire can be brought to bear on the spot. Pry up the 
 pickets with levers and attach ropes to the butts of trees and 
 haul away. 
 
 451. — Palisades and stockades are cut away with axes or 
 saws, the cuts being made near the bottom and ropes being at- 
 tached to the tops of the timbers; or dig out the earth at the bot- 
 tom and pull them over. 
 
 452.— Small pickets are cut through with the axe, or, if 
 possible, pulled up. 
 
 453.— Small pits are filled with earth, brush, or covered 
 by planks, fascines, or bales of hay. 
 
 454. — Automatic torpedoes are easily destroyed by driv- 
 ing animals up and down the line suspected of containing them. 
 
ClIAPTEIl XXT.— Camping Expedients. 
 
 455. — There are a few general principles which should be ob- 
 served in selecting a camp, whether the troops are to be estab- 
 lished in bivouac, in tents or in huts. These principles relate to 
 the health and comfort of the troops, the facilities for communi- 
 cation, the conveniences of wood and water, and the resources of 
 the locality in provisions and forage. 
 
 450. — For an intrenched camp the ground must be selected 
 with particular reference to its adaptability for defense and the 
 oamj) arranged with that object in view, at the same time observ- 
 ing as many of the other requirements as possible. 
 
 457. — Dry and liealtliy sites, dependent on soil: 
 Granite, metamorpliic and trap rocks, usually ; clay slates, but 
 drinking water is scarce; limestone generally, but the water is 
 hard, clear and sparkling though sometimes contaminated; deep 
 permeable sandstones, if the air and soil are dry ; deep gravels, 
 unless lower than surrounding country ; pure sand, deep and free 
 from organic matter ; icell cultivated soils generally ; gravelly 
 hillocks, the very best. 
 
 458.— ^Unliealtliy sites, dependent on soil: Magnesium 
 limestone; shallow sandstone underlaid with clay; clay and 
 alluvial soils generally ; rice fields ; made soils usually ; newly 
 plowed ground. 
 
 459.— Healthy sites, independent of soil: The best is 
 on a divide or saddle, unless too much exposed or without water. 
 The next best is near the top of a slope and the southern side is 
 preferable to the northern; banks of running rivers are good, 
 if not marshy. 
 
 460.— Unliealtliy sites, independent of soil: Enclosed 
 valleys, ravines, or the mouths of long ravines, ill-drained 
 ground, the neighborhood of marshes, especially if the wind 
 
258 Camping Expedients. 
 
 blows from them. If forced to camp near a marsh the windward 
 side should be selected and, if possible, have a hill or a screen of 
 woods or brush between the camp and marsh. Moss generally 
 indicates marshy ground. 
 
 461. — Sites affected by siirroiiiidiiig vegetation: 
 Herbage, or closely lying grass, is always healthy, but should be 
 kept cut and all weeds destroyed ; heavy brush about a marsh 
 should not be removed. Trees, in cold countries, break the winds; 
 in hot countries, they cool the ground and may protect against 
 malarial currents ; so should only be removed with judgment. 
 
 462.— In selecting camps, wood, water and grass should 
 be secured if possible, together with good drainage, but marshy 
 ground should not be occupied even for a night. 
 
 Old camp grounds sliould never be occupied if avoid- 
 able; instead, go as far as possible to the windward side of 
 them. 
 
 The site having been selected, the details of castrametation, or 
 the laying out of camps for the different arms will be found in 
 the authorized Drill Regulations of each. 
 
 463. — Water is more immediately necessary to life than 
 food. 
 
 Each man requires on the march for drinking and cooking 8 to 4: 
 quarts per day, and an equal amount for washing. In stationary 
 camps 5 gallons per da}^ for all purposes. 
 
 Hospitals require several times as much per man per day. 
 Horses, mules and cattle require from 6 to 10 gallons each per 
 day for drinking. It should be soft and clean, if possible. 
 Sheep and hogs require from 2 to 4 quarts each, per day. 
 464. — It is iinperative, on going into camp, that the supply 
 he immediately looked aftei^ and a guard placed over it. If the 
 supply be small, si^ecial precautions must be taken and an officer 
 put in charge. 
 
 465. — Good drinking Avater should be bright, colorless, 
 odorless, free from sediment, of pleasant and sparkling taste. 
 
 Rain water, collected from a clean surface, after the atmos- 
 phere has been well washed, is the purest in nature. Sp>rings 
 whose origins are remote from habitations, streams flowing 
 through uninhabited regions, and large lakes, furnish the next 
 best sources of supply. 
 
Camping Expedients. 259 
 
 466. — If the supply he from a lake, pond, or stream, separate 
 places for obtaining water for men and animals must be marked 
 out, and care taken that the margin is not trampled into mud and 
 the water made turbid. Where this is likely to occur when ani- 
 mals are watered direct from the source of supply, a hard bottom 
 should be formed for them to stand on, and a barrier formed to 
 prevent them going out too far. 
 
 It is better, when convenient, to arrange rows of sunken half 
 barrels, or board troughs raised above the ground, into which the 
 water can be drawn. If the supply be limited, it may be necessary 
 to connect the troughs to prevent waste; if not limited, each 
 should be supplied direct from the source and the overflow 
 drained off. Even when drinking from a running stream, the ani- 
 mals below get foul water. To prevent the ground around the 
 troughs becoming muddy it should be paved and drained along 
 the whole length and for a distance of 10 or 12 ft. back. Where 
 troughs cannot be constructed, trenches lined with puddled clay 
 may be made to answer. 
 
 Arrangements should be made so animals may be brought up 
 from one direction and leave in another without confusion or 
 crowding. ^ 
 
 467. — If the supply he from a stream, the water for drinking 
 and cooking for the troops is drawn highest up; for the animals to 
 drink, next below; and for washing, bathing, etc., lowest down; 
 while all drainage should enter below where any water is 
 taken. 
 
 If the stream be small it may be necessary to construct a series 
 of small reservoirs by building small dams across. Animals 
 drink better and more rapidly where water is 5 or 6 in. deep. 
 
 468. — If unavoidable, water from small ponds and shallow 
 wells should only be used after being boiled half an hour, then 
 aerated and filtered. 
 
 4:69,— If the supply he from springs, each should be enlarged 
 and surrounded by a low puddled wall, to keep out surface 
 drainage. They may be lined with casks or barrels charred in- 
 side, or gabions, afterwards working in puddled clay between the 
 earth and linings. The overflow may be received into a succes 
 sion of casks let into the ground close together. 
 
 Surface springs should be sought for in hollows, at the foot of 
 
200 CAMl'lMi Exi'KDlKiN'J'S. 
 
 hills, where the earth is moist, the grass unusually green, or the 
 thickest mists arise mornings and evenings. 
 
 470. — If water is not immediately available it may be neces- 
 sary to dig wells. The most expeditious means of doing so is to 
 use Well Augers. (PI. 58, Figs. 1, 2 and 3.) 
 
 47 1 .—To dig a well, an auger is attached to a rod sus jjended 
 from a rope passing over a pulley at the top of a derrick or tripod 
 and thence to a windlass. To the auger rod is secured an arm or 
 arms by which the auger is turned by hand and so screwed down 
 into the earth. About eight turns fills the auger, which is then 
 lifted, emptied and replaced. 
 
 472. — The auger for boring in quicksaiid (Fig. 3) is shaped 
 similarly to the ordinary wood-boring auger, but with a hollow 
 shank, so that, when lifted, no suction is produced. When the 
 thread becomes loaded the auger is drawn up into an enclosing 
 cylinder, removed from well and emptied. 
 
 473. — Driven Avells. The driven tube-well consists of a tube 
 about 3 ft. long, perforated with holes, and furnished with a steel 
 point of bulbous form (Fig. 4) and as many other plain iron tubes 
 as may be necessary. 
 
 The form of the point serves to clear a passage for the sockets 
 by which the tuSes are screwed together. 
 
 474. — To drive a Avell, a tube is screwed to the point (Fig. 
 5) and on this a clamp is fastened by two bolts at about 3 ft. from 
 the lower extremity of the point. Next, an iron driving weight, 
 or monkey, is slipped on the tube above the clamp. The tube thus 
 furnished is raised and held vertically in the center of a guide in 
 w^hich it is retained by a latch. The whole being now arranged 
 in position, ropes are made fast to the monkey and passed over 
 pulleys on the guide, and driving commenced by two men pulling 
 the ropes and allowing the monkey to fall on the clamp. As soon 
 as the clamp reaches the ground, the monkey is raised and held up, 
 the clamp loosened and raised 1.5 or 2 ft., tightened, and the driv- 
 ing continued as before until the top of the tube comes below the 
 hole in the top of the guide head, when the lengthening bar, 
 (Fig. 7) is dropped into the top of the well-tube. The lengthen- 
 ing bar consists of a length of the well-tubing with a smaller pipe 
 brazed into one end and projecting about 1 ft., which tits into the 
 well-tube. This bar keeps the tube steady and serves as a guide 
 for the monkey to slide on until the top of the well-tube reaches 
 
PLATE 58. 
 
 Fig.l3. 
 
Camping Expedients. 263 
 
 to within a foot of the ground. The lengthening bar is then re- 
 moved, another tube is screwed on, and the driving continued 
 until water is reached. A hollow iron plumb is frequently 
 lowered into the tube to ascertain when water has been reached 
 or whether earth of any kind has got into it. 
 
 Accumulations in the tube, of a loose sandy nature, can be 
 pumped up, by screwing a funnel (Fig. 8) on top of the tube, 
 then lowering into it through the funnel a smaller tube with a 
 pump attached. Water poured into the funnel runs down out- 
 side the smaller tube and is pumped up through it bringing the 
 mud and sand. When water is struck, and stands several feet in 
 the tube, the pump is screwed on to the well tube. 
 
 The well can also be driven without the use of the tripod sup- 
 ports (Fig. 6) care being taken to keep the tube vertical by means 
 of guy ropes. Such a well can be driven from 10 to 20 ft. per 
 hour. The tubes can be withdrawn without damage by reversing 
 the operations of driving. (Fig. 9.) 
 
 475. — ^The tube-well is not intended for piercing rock, or solid 
 stone formations, but is quite capable of penetrating very hard 
 and compact soils. When striking rock, stone, or deep beds of 
 clay, it is best to pull up the tube and try in another spot, for by 
 going a little distance ojff water will in many cases be found. 
 
 476. — Clariflcation of Abater. Water usually contains 
 mineral and organic substances in solution and in suspension. 
 Substances in solution completely disappear and cannot be en- 
 tirely filtered out. Substances in suspension do not entirely dis- 
 appear and may be filtered out. 
 
 477. — Hard water contains one or more substances, as lime, 
 magnesia, iron and others, in solution, which are liable to pro- 
 duce intestinal troubles to persons unaccustomed to them. 
 Cooking vegetables in it is very difficult. Washing with it re- 
 quires a great deal of soap. 
 
 The hardness of water may be partially removed by boiling for 
 half an hour or so, or by adding a small quantity of washing 
 soda, or by adding a couple of ounces of quicklime to 100 gals. 
 
 478. — Substances in suspension may be largely removed by 
 precipitation and filtration. 
 
 479. — Precipitation is allowing such matter as will to settle 
 through its greater specific gravity, or, by inducing it to do so 
 through some harmless chemical or mechanical action. For 
 
liOl CaMIMXC; iilxi'EDlET^TS. 
 
 which purpose nuiy be used about 6 grains of crystallized alum to 
 the gallon, or tannin in small quantities and letting stand several 
 hours before using; bruised cactus leaves, also tea leaves that 
 have been used act similarly; citric acid, 1 oz. to 16 gal., or borax 
 and alum, i^ oz. each, or 1 to 2 tablespoonfuls of ground mustard 
 to a barrel improves water. 
 
 4S(). FiKratioii is iiiccluinicnlly arresting and atlfact ini;- 
 susjjended matter, and removing dissolved matter in the water. 
 Filtering materials act only for a short period and should be fre- 
 quently cleaned. 
 
 481. — Materials icliich may he used are sponge, wool, and like 
 articles for straining, but must be constantly removed and 
 cleaned. Clean sand, gravel, and porous stone remove suspended 
 matter, but have little or no effect on dissolved organic matter. 
 Iron sponge, a compound of sawdust and iron oxide heated in a 
 furnace, and Carferal, a compositi(m of charcoal, iron and clay, 
 are efficient for removing mineral matter. Bone black or animal 
 charcoal, and wood charcoal, when freshly burned, absorb mineral 
 Hiattcr for a couple of weeks, but their chief action is on organic 
 matter. 
 
 482.— Cliarcoal may be made by digging in the ground a 
 circular pit, some 6 in. deep by 4 or 5 ft. across, then placing a 
 large pole or bundle of brushwood vertically in the center. 
 Around this the wood to be burned is piled, forming a kind of 
 cone. The pile is then covered with brush, and on this a layer of 
 4 or 5 in. of earth. (Fig. 10.) The center pole is then removed 
 and a fire lighted in its place, receiving air from vents left at the 
 bottom for that ijvirpose. The fire proceeds from the center out- 
 wards, and, if burning properly, the smoke is thick and white. If 
 it does not spread to every part new vents must be made. If the 
 smoke becomes thin and a blue flame appears, it is burning too 
 fast, and vents must be stopped up or more earth thrown on. 
 When the smoke ceases to escape, the vents and chimney are 
 closed and the pile allowed to stand for a couple of days until it 
 cools. 
 
 From 20% to 25% of charcoal is thus obtained. 
 
 483.— A coiiveiiieiit portable Alter (Fig. 11) is made 
 by taking a small cylinder of compressed carbon and inserting it 
 in a rubber tube in such a manner that the carbon end may be 
 
Camping Expedients. 2G5 
 
 immersed in the water, then applying the mouth to a mouthpiece 
 at the other end of the tube, and drawing the water through. 
 
 484. — Tlie Success Filter, (Fig. 12) consists of a cylindrical 
 I^orous stone 4 in. long by 4 in. in diameter with a hole bored in 
 one end. In this hole is fitted a rubber gasket through which 
 passes an iron tube that is fastened into the bottom of a barrel, 
 jar or bucket. The water filters through the stone into the hole 
 inside and passes out through the tube into a receiving vessel 
 below. (Fig. 13.) 
 
 By fastening the iron* tube into the bottom of a large empty 
 tomato or peach can, in which the stone is placed on the tube and 
 wedged fast, then fastening a rubber tube 2 or 3 ft. long on the 
 iron tube outside of the can, a syphon filter is obtained. The 
 action is set up by exhausting the air from the stone, after the 
 can and stone are immersed in water, by sucking on the end of 
 the rubber tube until the water is started. 
 
 485.— A simiile water filter may be made by stuffing a 
 piece of sponge in a hole in the bottom of a cask, flower pot, or 
 other vessel, (Fig. 14) then placing above this a layer of coarse 
 sand, then a layer of pounded charcoal, 3 or 4 in. thick, then an- 
 other layer of coarse sand, and on this a layer of coarse gravel. 
 The layers should be thick as possible, and tightly compressed, 
 and washed thoroughly clean before being used. The different 
 layers may be prevented from mixing by perforated boards, or 
 otherwise. Another form may be made as shown in Fig. 15. 
 
 486. — Casks, or barrels, charred on the inside (and occasion- 
 ally cleaned, brushed, and recharred) improves water. 
 
 487.— I^atriiies. Arriving on the site of a camp, one of 'the 
 first duties is to designate the places to attend to the calls of na- 
 ture, and there dig latrines. Urinals should be placed nearer the 
 camp and of easy access. 
 
 The only exception to digging latrines is when the command is 
 very small, is certain to march the next day, and no other troops 
 are to follow. 
 
 488. — Latrines and urinals should be so placed as not to be in 
 the course of the prevailing winds to the camp, and must be so 
 situated that they cannot pollute the water, either directly or by 
 
 489. — A small, shallow trench will suffice for a single night, 
 and should invariably be filled in the morning before marching. 
 
2GG Campin(s Expedients. 
 
 For longer i)erio(ls, a trench 2 or 3 ft. wide at top, from 2 to 10 
 ft. deep, and 12 to 15 ft. long for every 100 men, should be dug, 
 throwing the earth to the rear, from which a layer of a few inches 
 should be thrown into the trench every day, or oftener if neces- 
 sary. Lime or charcoal may also be used to deodorize the soil. 
 
 It is better to increase the number of trenches than to make 
 ;iny one trciu-h too long. 
 
 Shallow hitrines should be discarded when tilled within a foot 
 of the surface, and completely tilled in with earth; deep ones 
 when within 3 or 4 ft. of the surface. 
 
 All latrines should be filled in and marked before marching. 
 
 490. — In temporary camps, latrines may be provided with seats 
 of a pole and a back, and be screened by bushes, canvas, or 
 other means. (Pig. 'iO.) 
 
 491. — Kitclieiis. On going into camp, kitchens should be 
 promptly established and in the same relative positions as if the 
 camp were going to last a month or more. A pit should be dug 
 near by for strictly liquid refuse, w^hile solid matter should be 
 placed in a l)()x or barrel for the ])oliee party to remove. 
 
 492. Wlioi fuel is plentiful, a trench of sufficient length and 
 about 1 ft. deep may be dug to contain the fire over which the 
 kettles are hung from supports. (PI. 59, Fig. 1.) 
 
 If fuel is scarce, then dig a trench as above in the direction of 
 the wind but a little narrow^er than the diameter of the kettles to 
 be used. Place the kettles over the trench and fill in between 
 with stones, clay, etc., forming a kind of flue. The draft may be 
 increased by building a chimney of sods, stones, etc., on the lee- 
 ward end and enlarging the windward end. (Fig. 2.) 
 
 If the camp is to be for a long time and the direction of the 
 wind liable to vary, a number of such trenches may be dug radi- 
 ating from a common point, over w^hich point a chimney is con- 
 structed. Then, whatever the direction of the wind, the trench 
 opening in that direction can be used, the others being 
 closed. 
 
 The trenches should have a slight fall from the chimney back 
 for drainage, and a means for the water to escape. If the kettles 
 are small or of various sizes, rests of stones, scraps of iron, etc., 
 may be placed across the trench. 
 
 A square hole may be dug for the fire with trenches lor draught 
 
PLATE 59, 
 
Camping Expedients. 269 
 
 at the corners, the kettles being placed on rests over the fire. 
 (Fig. 3.) 
 
 4:93.-- A grillage ov Jcind of grate about 1 ft. high, made of 
 gas-pipe or bar-ironjis sometimes used to set over the fire, and on 
 this are placed the kettles. (Fig. 4.) These are sometimes made, 
 with movable joints so as to be closed for transportation. 
 
 494. — If a covered kitchen is desired, either a trench similar 
 to Fig. 2, can be dug, or one above ground can be built with 
 stones and sods and a tent placed over it, or a cover con- 
 structed. 
 
 495. — To bake bread, when none of the portable ovens of the 
 Commissary Department are carried, improvised ovens must be 
 constructed. The simplest method is to take a barrel with one 
 head out (one with iron hoops best), lay it on its side in a hollow 
 in the ground and then plaster over with wet clay 6 to 8 in. 
 thick, then with a layer of dry earth equally thick, leaving an 
 opening of 3 or 4 in. at the top of the closed end for a flue. The 
 staves are then burned out by a hot fire which also bakes the 
 clay covering, forming an arched oven. To bake, after heating, 
 the front and flues are closed. Or a pit may be dug from 6 to 12 
 in. deep and 4 by 5 ft. for the hearth, over this form an arch with 
 a hurdle or any other material available (Fig. 7), with a chim- 
 ney at one end and a door at the other. Then plaster and cover 
 the arch as in the barrel oven and bake the clay covering. 
 
 496. — An oven may be excavated in a clay bank (Fig. 6) and 
 used at once. 
 
 497. — The Buzzacott Army Field Oven (Fig. 8) which is an. arti- 
 cle of issue by the Commissary Department, is a complete camp 
 cooking outfit consisting of oven, baking and frying pans, etc. 
 All are securely packed togther and can be conveniently carried 
 in the feed box of an army wagon or on a pack animal. To use 
 it, a bed of live coals is first obtained, then the oven after being 
 heated is placed on rests over a bed of the coals, and a layer of 
 sand sprinkled evenly over the bottom of the oven to prevent 
 burning out. In this is placed the pans of prepared food on suit- 
 able rests and the whole covered with a hood. On the hood is 
 scattered a layer of live coals and burning brands. Broiling, 
 frying, coffee making, etc., may be done on top of the oven by 
 using the remaining pans, rests, etc., at the same time that the in- 
 terior is used for baking. 
 
270 Camping Expedients. 
 
 498. — Drainage. The 'camp being located, a system of sur- 
 face drainage should be carefully traced and constructed. As 
 soon as a tent is pitched it should be surrounded by a shallow 
 ditch outside, emptying into a company ditch. The proper 
 •method of doing this is to have the inner edge of the ditch come 
 just inside of the skirt wall of the tent to catch the water run- 
 ning down the side of the tent and to drain the interior. 
 
 The picket should be inside ot the ditch. (Fig. 9.) To bank 
 earth up against the tent soon rots the bottom of the wall. 
 
 499. — Beds. The ground being generally too damp to lie upon 
 directly, all should sleep upon some dry material as straw, leaves, 
 or preferably a low platform constructed of small branches and 
 poles, if available. (Pig. 10.) 
 
 If required to sleep upon the ground, one w411 sleep more com- 
 fortably if he scrapes out a small hollow for his hips. Straw, 
 hay, etc., for sleeping upon may be made into mats with the 
 Malay Hitch as in Fig 11. 
 
 500. — Windbreaks. When troops bivouac, some protection 
 from wind may be obtained by building up to the windward a 
 pile of earth, sods, etc. Where trees are available, by resting a 
 pole on two forked sticks, 4 or 5 ft. high, against which branches, 
 thick end up, are piled at an angle of 45° on the windward side. 
 (Fig. 12.) Hurdles similarly placed, supported and covered 
 (Fig. 13), canvas or blankets secured as in Fig. 14, straw or hay 
 clamped between poles as in Fig. 15, may be used. 
 
 By throwing up either a half or whole circle of earth 18 ft. in 
 diameter, from a ditch on the outside, some protection may be ob- 
 tained. On the bank so formed additional wind-breaks may be 
 placed or a covering extended over it all may be made. (PI. 
 60, Figs. 1 and 2.) 
 
 501. — In cases of prolonged occupation, if tents are not avail- 
 able, the troops should build shelter of some kind. 
 
 Huts may be built of timber, logs, brushwood, adobe, etc., in 
 connection with straw, bark, sods and similar materials. 
 
 All huts should, if possible, have their floors raised above the 
 ground to allow free circulation of air underneath. (Fig. 3.) 
 Only in very dry soil and when not to be occupied long is it allow- 
 able to sink them, if avoidable. Space between huts in the same 
 row should equal the height of walls, and passage in rear equal 
 the height of ridge. Hut sites should be well pounded. 
 
PLATE 60. 
 
Camping Expedients. 273 
 
 Huts are ordinarily constructed to contain a small number of 
 men, but the sizes and details of construction will depend greatly 
 upon the site and materials available. 
 
 A very fair minimum allowance per man of bed space is about 
 2.5 ft. X 7 ft., with a passage at foot from 2 to 4 ft. 
 
 Thus, the plan for 8 men may be taken at 10 ft. x 18 ft., 
 arranged as in Fig. 4. For 12 men, 15 ft. x 18 ft. For 16 men, 20 
 ft. x 18 ft. For 20 men, 25 ft. x 18 ft. 
 
 For calculating the accommodation at the above rates, allow 
 one man per pace of length for a single row of beds and 2 men per 
 pace of length for a double row of beds. 
 
 502. — Major Smart, Medical Department, reconmiends as best 
 a modification of the Army of the Potomac hut, of rectangular 
 plan (Fig. 5), 7 ft. x 13 ft., height to eaves 6 ft., to ridge 10 ft.; door 
 in middle of one long side, chimney opposite door on outside of 
 wall ; on each side of doorway a double bunk. This hut to accom- 
 modate 4 men. 
 
 If logs are used, the ends are trimmed with an axe where they 
 lap at the corners, so they will lie one upon the other throughout 
 their length. 
 
 503. — ^If made of small timber, some style, as in Fig. 6, with 
 thatched roof, might be used. 
 
 If, for any reason, it is not desirable to build huts as above, 
 forms may be used as shown in Fig. 7, or hurdles, as in Fig. 8. 
 
 504. — Sentry boxes may be made as in Fig. 9, the side cover- 
 ing consisting of watling described in Chap. IX. and the roof 
 thatched. 
 
INDEX. 
 
 
 Par. 
 
 Abatis, consists of, how made. . . 50 
 in shallow ditch, of small 
 
 branches^in front of glacis ... 51 
 
 how destroyed 450 
 
 Advanced Post, rear of 204 
 
 Anchors, number of, scarcity of. 343 
 
 substitutes for 344 
 
 use of 342 
 
 weights of, names of parts of.. 341 
 
 Angle, equal to a given angle, 
 
 method of laying out 22 
 
 right^ method of laying out. . . 18 
 
 rd-entrant, salient, shoulder.. 82 
 
 Approaches, in siege operations 
 
 constructed by infantry 154 
 
 Area, of rectangle, of trapezoid, 
 
 of triangle, method of finding. 25 
 
 Artillery, in defense of village, 
 
 where placed 215 
 
 in woods 179 
 
 projectiles 9 
 
 to be placed outside of works 
 
 87, 151 
 
 Axe, use of... 44 
 
 Balks, bay, etc., defined 248 
 
 Ballast, for R. R., object of 377 
 
 Bank, Gun, definition of, rela- 
 tive advantages of, aud embra- 
 sures 70 
 
 dimensions of, where placed.. 102 
 
 space required for 100 
 
 Barricade, use and construction 
 
 of .'... fil 
 
 for doors of baildings 195 
 
 Batteries, telegraph, how carried 418 
 
 Bay, length of, how found 317 
 
 Beds, camp 499 
 
 Far. 
 
 Berni, definition of, etc 65, 99 
 
 advantages and disadvantages 
 
 of 78 
 
 Binding, fascines 117 
 
 Bisecting: an angle, method of. . . 20 
 Blocks, description of, etc., run- 
 ning 228 
 
 Blockhouse, use and construc- 
 tion of 144 
 
 in isolated places 145 
 
 Boat, buoyancy of how found 316 
 
 Box or barrel, to sling 223 
 
 ponton, construction of 323 
 
 Brackets, telegraph 410 
 
 Breaking loads of ropes 218 
 
 Breaks in telegraph lines 419 
 
 Bridge, anchored to hawser .... 343 
 
 beams, of iron, how destroyed 439 
 connection of with shore, how 
 
 made 350 
 
 computing strength of 255 
 
 double lock 275 
 
 expedients 278 
 
 floating, description of .... 306 
 
 flying, description of 309 
 
 forming, by successive pon- 
 tons 346 
 
 forming, by parts 347 
 
 forming, by rafts 348 
 
 forming, by conversion 349 
 
 masonry, how destroyed 443 
 
 maximum load for 247 
 
 name of, how derived 248, 310 
 
 Paine's 260 
 
 pile 269 
 
 protection of, from floating ob- 
 jects 352 
 
Iiri<lj;:e, coiitiiiiK'tl. 
 
 railroad, repair of 405 
 
 requirements of 244 
 
 short, how anchored 343 
 
 single lock .. ... 274 
 
 skiffle sling 2(<) 
 
 spar railroad 245 
 
 suspension 2s()-6 
 
 suspension, how destroyed... Ill 
 
 swing o51 
 
 trail 308 
 
 treble sling , . . 277 
 
 twenty-five feet or less 258-i) 
 
 twenty-five feet or over. 26 1, 271, 276 
 
 ISroadskle village, how de- 
 fended 213 
 
 IJrush huts 503 
 
 sentry boxes 504 
 
 Brushwood, bundles of, vai ic tit s 
 
 and sizes 115 
 
 rate and method of clearing.. . 46 
 
 roads 371 
 
 Building:, defense of, how re- 
 garded, first line, how far dis- 
 tant 191 
 
 doors of, how barricaded 195 
 
 flank defense of 199 
 
 how used for defense 189 
 
 loopholing of 194 
 
 materials used in defense of . . 200 
 
 precautions in defense of. 198 
 
 removal of . 48,445 
 
 requisite of, for defense 190 
 
 steps in preparing for defense 193 
 
 windows of, how barricaded.. 197 
 
 Buoyancy of casks, how deter- 
 mined 325 
 
 liuzzacott oven, description of.. 497 
 
 Cable, charge of explosive to cut. 441 
 
 swinging, length of 309 
 
 Camp beds 499 
 
 Camps, drainage of 498 
 
 dry and healthy sites for.. ..457, 459 
 
 selection of 455, 456, 462 
 
 UBhealthy sites for 458,460 
 
 windbreaks for 500 
 
 Canister, description of ll 
 
 Canvas ponton, U. S 319 
 
 Par. 
 
 Canvas raft, description of 303 
 
 Capital of field works 82 
 
 Caponiers, objections to 85, 146 
 
 stockade work used for 188 
 
 used in flanking buildings 199 
 
 Capstan, description of 212 
 
 Casemate, use and general form 
 
 of 138 
 
 how constructed, floor siiace 
 
 in i;;n 
 
 Cask, buoyancy of, how deter- 
 mined 325 
 
 Casks, closed, piers of, construc- 
 tion of 330 
 
 open, piers of, construction of 328 
 
 open, safe load of 329 
 
 Centrifugal foree of train 383 
 
 Charcoal, uses of 481 
 
 how made 482 
 
 Charges, several exploded at 
 
 same time 429 
 
 Chess described 218 
 
 Chevaux-de-f rise 56 
 
 Choker fascine, description and 
 
 use of 117 
 
 Circular village, how defended 214 
 
 Clarification of water 476 
 
 Clay roads 367 
 
 Command of works, definition 
 
 of 71 
 
 Common trench work, how 
 
 made, uses of 156 
 
 Communications, construction 
 
 of 373, 374 
 
 in woods 177 
 
 Concentrated load on bridge. . . 253 
 
 Conductor,metallic, for telegraph 408 
 
 Connecting wires, how done. . . 428 
 
 Corduroy roads 370 
 
 Counter-scarp, definition, etc.. 65, 79 
 
 gal leries 85 
 
 Cover for guns 39 
 
 in woods, how obtained 176 
 
 Crab 240 
 
 Crest, exterior 67 
 
 interior 66 
 
 military 153 
 
 Crib piers, construction of 268 
 
 ponton, construction of 322 
 
iWDEX. 
 
 •^n 
 
 Par. 
 
 Cross, in telegiaj)h wires 419 
 
 Cross arms, telegraph 110 
 
 Crossing: of rivers, selection of, 
 
 how determined 289 
 
 Crossing's, railroad 385 
 
 CroAv's feet 56 
 
 Cutting:, how defended 171, 1T2 
 
 Dead load on bridges 253 
 
 Debris, removal of 48 
 
 I>efenders of woods, number of. 179 
 
 Defense, of fences 168 
 
 passive, with respect to lines 
 
 of works 149 
 
 Defilade, definition of 88 
 
 in plan , 89 
 
 in section 90, 91 
 
 with two planes 92 
 
 Depth of fords 290 
 
 Derrick, description of 237 
 
 in using 240 
 
 Destroying: railroads, by whom 
 
 done 399, 400 
 
 by whom ordered 401 
 
 of telegraph lines 420 
 
 Detonator 424 
 
 with fuse 426 
 
 electrical 427 
 
 Dig:g:ing: wells 470, 471, 472 
 
 Dimensions of loop holes 164 
 
 Disabling: railroads 398 
 
 Distance between two inaccessi- 
 ble points, method of finding.. 24 
 
 Distributed load 253 
 
 Ditch. 65.81,361 
 
 depth of 96 
 
 method of digging 101 
 
 Doors, how barricaded 195 
 
 Double lock bridge 275 
 
 Drains, catch and covered 361 
 
 Drainag:e of camps 498 
 
 of roads .... 361 
 
 Drinking: water 465-9 
 
 Driven wells 473-4 
 
 Driving: piles 270 
 
 Dynamite, use of with detonator 429 
 
 Karth. excess of at salients 97 
 
 in embankments, space occu- 
 pied by 96 
 
 Far. 
 Karth, <'ontinued. 
 
 loosening of in the front of 
 
 trenches 38 
 
 roads 366 
 
 Earthworks, calculation of di- 
 mensions of 95 
 
 Klectrical fuse or detonator. . . . 427 
 
 Kmbankment, how defended. . . 170 
 
 Embarkation, in ferrying 301 
 
 Embrasure 69 
 
 used when, details and con- 
 struction of 103 
 
 space required for 100 
 
 Eng:ine, locomotive 389 
 
 Eng:ineering:, Military, Field, 
 
 definition of 1 
 
 Epaulement, gun 39, 70 
 
 relative advantage of, and em- 
 brasures 70 
 
 Equilateral triang:le, method 
 
 of laying out . 21 
 
 Escape in telegraph lines 419 
 
 Escarp 65,79 
 
 Expedients, bridge. 27S 
 
 Exploder, electrical 428 
 
 Explosives, kind generally used. 421 
 
 table of comparative strength 
 
 of 448 
 
 Extending: along zig-zag 155 
 
 working party 109, 110, 155 
 
 Extension on flying sap, method 
 
 of 158 
 
 Eye-bars, how cut 440 
 
 Eye splice, to make 222 
 
 Faces of works 82 
 
 Farms, principles of defense ap- 
 plied to 203 
 
 Fascines, size, weight, and mak- 
 ing of - 117 
 
 Fastening:s, rail 382 
 
 Faults in telegraph lines 419-20 
 
 Fences, defense of 168 
 
 removal of when 48 
 
 Ferry, the rope 307 
 
 Ferrying: by boat, embarkation, 
 
 and unloading 301 
 
 by raft 302 
 
Index. 
 
 Field gfunn, destruction of. 
 
 range of 
 
 Field level, description of 
 Filters, portable 
 
 simple 
 
 Filtering water 
 
 Fire, as regards direction, trajec- 
 tory 
 
 double tier of, for walls 
 
 sector of, discussion of 
 
 working parties exposed to . . . 
 
 Flank defense of buildings 
 
 Flanks of works 
 
 Floor space in casemates 
 
 Floating piers, essentials of 
 
 Flying bridges, raft for 
 
 telegraph lines 
 
 sap, description of 
 
 sap, method of extension along 
 Fords, how made impassable .... 
 
 with sandy bottom 
 
 depth of, requisite of 
 
 in mountainous country 
 
 level country 
 
 how marked, position of, how 
 determined 
 
 precautions in selecting 
 
 re-examination of 
 
 where found 
 
 Foreground, extent of clearing. 
 Form, strap-iron gabion 
 
 wicker gabion 
 
 of roads 
 
 Forming bridge by conversion. 
 
 by parts 
 
 by rafts 
 
 by successive pontons 
 
 Forts, how distinguished 
 
 Fort Wagner, parallels and ap- 
 proaches to 
 
 Fortification, classes of 
 
 compared to other military ex- 
 pedients 
 
 object of 
 
 subdivision of field 
 
 Fougasse, construction, use, and 
 
 charge for 
 
 Fraises, construction and use of. 
 
 Par. 
 
 447 
 
 13 
 
 26 
 
 483-4 
 
 485 
 
 480-1 
 
 167 
 86 
 111 
 199 
 82 
 139 
 314 
 340 
 418 
 157 
 158 
 58 
 291 
 290 
 291 
 291 
 
 293 
 295 
 296 
 292 
 
 43 
 120 
 118 
 359 
 349 
 347 
 348 
 346 
 
 84 
 
 160 
 2 
 
 Par. 
 Frogs 384 
 
 railroad, how destroyed 436 
 
 Fuse 425 
 
 how used 426 
 
 Gabions, hoop or strap iron. 
 
 
 weight and making of 
 
 120 
 
 method of carrying . . . 
 
 157 
 
 sheet iron, making of. . 
 
 191 
 
 wicker, size, weight, and mak- 
 
 
 ing of 
 
 118 
 
 making of without a gabion 
 
 
 form 
 
 119 
 
 Gates, desti uction of 
 
 444 
 
 Gin, description of 
 
 239 
 
 using 
 
 '?40 
 
 lashing, making of 
 
 227 
 
 Glacis 65, 80 
 
 Gorge of works 
 
 82 
 
 Gradient, limiting of roads 
 
 355 
 
 Grain, removal of standing 
 
 47 
 
 Grass, removal of standing 
 
 47 
 
 Gravel roads 
 
 368 
 
 Grillage 
 
 493 
 
 Gauge of railroads 
 
 380 
 
 Guarding water supply 
 
 464 
 
 
 4?? 
 
 how detonated 
 
 423 
 
 Gun epaulements and pits 
 
 39 
 
 Gunpowder, how ignited 
 
 426 
 
 
 447 
 
 Gutters 
 
 361 
 
 Hard Water 477 
 
 Hasty Demolition, tables show- 
 ing charges for 448 
 
 Head Logs, use of 36 
 
 Healthy Camps 457, 459 
 
 Hedges, advantages of, how de- 
 rived, principles of 169 
 
 Hedges, removed, when 48 
 
 Heights over which tire may be 
 
 delivered 13 
 
 Hitches, knots, etc 219 
 
 Holdfasts, description of 243 
 
 Hoops, making of, for strap iron 
 
 gabions 120 
 
 Horse, power of on grades 356 
 
 Houses, demolition of 445 
 
Index. 
 
 279 
 
 Par. 
 
 Hurdles, continuous, construc- 
 tion of 123 
 
 size, weight and making of. . . 122 
 
 Huts, brush 503 
 
 how made, etc 501 
 
 Army of Potomac, (Major 
 
 Smart's) 502 
 
 allowance of space in , . . . . 501 
 
 Ice 297 
 
 thickness of, how increased. . . 299 
 
 thickness of for various loads. 298 
 Infantry Approaches in siege 
 
 operations 154 
 
 Intervals between trenches, 34 
 
 method of taking by, working 
 
 parties 109 
 
 usual for working parties. . .111,112 
 
 Insulators, telegraph 412 
 
 Insulated wire joints 429 
 
 Iron plates, how cut 438 
 
 Isolated pits 32 
 
 Joints for telegraph wire 417 
 
 American twist . 417 
 
 insulation of 429 
 
 rail 381 
 
 Junctions, railroad 886 
 
 King: post truss 272 
 
 Kitchens 491-2 
 
 covered , 494 
 
 Knots, hitches, etc 219 
 
 Lances, military, telegraph 418 
 
 Lashings, gin 227 
 
 rack 224 
 
 shear 226 
 
 transom 225 
 
 Latrines 487, 490 
 
 Leaks in telegraph line 419 
 
 Level, field, description of 26 
 
 uses of 27 
 
 Lines, cutting of ditch and 
 
 trench 101 
 
 Line, first, falling back past 
 
 houses 192 
 
 parallel to given line, method 
 
 of constructing 23 
 
 Lines, second and third in woods. 178 
 
 Par. 
 Load, distributed, dead, and 
 
 moving 253 
 
 Loading: horses in railroad 
 
 cars 393, 394 
 
 Loading: wagons on railroad 
 
 cars 396 
 
 Log, cubic contents of 254, 335 
 
 buoyancy of 334 
 
 Logs, piers of, construction of. . . 338 
 
 Long splice, to make 321 
 
 Loop holes, dimensions of 164 
 
 height of, how influenced 166 
 
 how made 36 
 
 in buildings 194 
 
 Loopholing walls 163 
 
 method of 164, 165 
 
 Macadam roads 364 
 
 Machicoulis gallery, construc- 
 tion of, use of 199 
 
 Magazine, general plan of. . . .141, 142 
 
 large, small in parapet 140 
 
 of gabions and fascines 143 
 
 rifle, range, speed, and fire of. 14 
 
 Magneto exploder 428 
 
 Marking fords 293 
 
 Materials for bridges 287 
 
 for road coverings 365 
 
 revetting 114 
 
 used in defense of buildings. . 200 
 
 Maximum load for bridge 247 
 
 Merlon, definition of, rule as to 
 
 minimum length of 104 
 
 Metal ties 379 
 
 Military engineers, duties of.. 421 
 
 Military telegraph lines 418 
 
 Mines, land 60 
 
 Moving or live loads 253 
 
 Objects, floating, protection of 
 
 bridge from 852 
 
 Obstacles, conditions governing 
 
 use of 49 
 
 Office telegraph, treatment of 
 
 when captured 420 
 
 Ovens 495-6 
 
 Buzzacott 497 
 
 Organizations, or parts of, used 
 
 as working parties 42 
 
 Overhaul tackle 231 
 
Ini^kx. 
 
 rar. 
 
 I*aiiie'8 britljjo 260 
 
 Falisatles, consist of 54 
 
 I'aliKadiii^, destruction of l;>3, 451 
 
 l»airiiig: 118 
 
 I*aii coupe 102 
 
 Parados, definition of (58 
 
 method of determining height 
 
 of 93 
 
 Parallel to a given line, method 
 
 of constructing 23 
 
 Parallels and approaches, Fort 
 
 Wagner 160 
 
 Parapet .63, 67, 81 
 
 Perpendicular to a line method 
 
 of erecting 19 
 
 Pickets, forked 119 
 
 gabion 118 
 
 Piers, bridge, how destroyed. . .440,443 
 
 Floating essentials of 314 
 
 of casks, precautions in using. 327 
 of open boats, precautions in 
 
 using 315 
 
 of open casks, construction of. 328 
 of closed casks, construction 
 
 of 330, 333 
 
 of logs, construction of 338, 339 
 
 Pile bridges 269 
 
 driving 270 
 
 Plank roads 372 
 
 Planks, when used for revet- 
 ments 124 
 
 Plows, use of 40 
 
 Ponton canvas, U. S 319 
 
 crib, construction of 322 
 
 Ponton, box, construction of 323 
 
 reserve train , U. S 320 
 
 wagon body, construction of. . 324 
 
 Poles, telegraph, how numbered. 415 
 
 telegraph, how guyed, number 
 
 to mile, preparation of, 
 
 protection from lightning, 
 
 raising of, size of, where 
 
 run 409-411 
 
 Portable ranip 393 
 
 filters 483-484 
 
 truss 279 
 
 Position, defensive, definition 
 
 of, chief requisite of 4 
 
 choice of 42 
 
 Par. 
 Position, continued. 
 
 strength of 153 
 
 conditions to be fulfilled 4 
 
 of ford, how determined, 293 
 
 lN)vver of horse on slopes 356 
 
 exerted by man 236 
 
 of tackle 2S3-5 
 
 Precautions, additional, in de- 
 fending buildings 198 
 
 in fording 295 
 
 Profiles, angle, how determined. 94 
 definition and nomenclature 
 
 of 65 
 
 normal, of field works 99 
 
 Profiling, method of 94 
 
 Pulley, description of 228 
 
 Queen post truss. 
 
 Rack, fascine, description and 
 
 use of 
 
 lashing to make, 
 
 Kaft, canvas, description of 
 
 for trail bridge 
 
 of skins 
 
 Rafts, advantages and disad- 
 vantages of 
 
 for flying bridge 
 
 swinging, for traffic 
 
 Rail, fastenings 
 
 form of . . . . 
 
 joints 
 
 how cut 
 
 straightening 
 
 Railroad, bridge 
 
 crossings 
 
 junction 
 
 wye 
 
 turntable 
 
 Railroads, duties of troops in 
 
 connection with 
 
 description of 
 
 destroying and disabling, by 
 whom done 398- 
 
 how disabled and destroyed. 402, 
 
 repair of 
 
 rolling stock, buildings, etc.o90. 
 Ramp, portable 
 
 Major Fechet's .. 
 
 117 
 224 
 
 303 
 308 
 304 
 
 305 
 340 
 351 
 
 382 
 380 
 381 
 435 
 407 
 245 
 385 
 386 
 387 
 388 
 
 375 
 377 
 
 -400 
 403 
 404 
 391 
 393 
 397 
 
Index. 
 
 281 
 
 Par. 
 Ramp, continued. 
 
 semi-permanent 395 
 
 simple form of 392 
 
 Kandins: 122 
 
 Redoubts 84 
 
 Reliefs, 1st, 2nd and 3rd, of work- 
 ing party, cutting lines for 
 
 tasks of 101 
 
 of field work, definition of 72 
 
 Reserve train, ponton, U. S 320 
 
 Revetment, definition of 113 
 
 making and qualities of adobe. 137 
 
 of brushwood 128 
 
 of fascines 129 
 
   of gabion 130 
 
 of hurdle and continuous hur- 
 dle 131 
 
 of pisa 136 
 
 of plank 124, 132 
 
 of posts 135 
 
 of sand bag 134 
 
 of sod 126, 133 
 
 of timber 125, 132 
 
 Ribbands ... 55 
 
 Road bed 360 
 
 defense of 173 
 
 matei ials 365 
 
 Roads, brushwood 371 
 
 clay 367 
 
 corduroy 370 
 
 desirable conditions in 354 
 
 drainage of 361 
 
 earth 366 
 
 form of 359 
 
 gravel 368 
 
 knowledge of 353 
 
 limiting gradients of 355 
 
 plank 372 
 
 repair of 369 
 
 surface of 362 
 
 width of 358 
 
 Roadway, weight of, steadiness 
 
 of 313 
 
 width of on bridges 248, 280-6 
 
 Rope, breaking loads of, weight 
 
 of .. 218 
 
 composition, size of, etc 216 
 
 Rope, parts of 219, 230 
 
 rule for strength of 217 
 
 Par, 
 
 Round timber, strength of 255 
 
 Running: blocks 228 
 
 Sag: in telegraph wire •••• 414 
 
 Salient village, how defended... 212 
 Sand bag:s, materials, size capa- 
 city, and filling 127 
 
 Sap, flying, description of 157 
 
 Saw, teeth of 44 
 
 use of 44 
 
 Sector of fire, definition of and 
 
 application to different traces. 86 
 
 Selecting: camps 455-6, 462 
 
 Sentry boxes 504 
 
 Sewing:, method of, for gabions 
 
 and hurdles 118 
 
 Shear lashing:s , 226 
 
 Shears, description of 238 
 
 method of using 240 
 
 Shell 9 
 
 charges, how exploded 12 
 
 shrapnel 10 
 
 Short splice, to make 220 
 
 Shovelers, extra, provided when 101 
 
 Siding's, railroad 384 
 
 Sing:le lock bridg:e 274 
 
 Sing:le sling: bridg:e 276 
 
 Site for floating bridge, selection 
 
 of 311 
 
 plane of, definition 73 
 
 Size of teleg:raph wire. ......... 408 
 
 Slewing • 122 
 
 Slope, banquette 65 
 
 description of 17 
 
 exterior 65, 77 
 
 interior 65, 75 
 
 superior 65, 76 
 
 Small pits, how made 57 
 
 how destroyed 453 
 
 Snatch block 228 
 
 Sods for revetments, cutting and 
 
 laying 126 
 
 Span, superstructure, stringers or 
 
 balks, side rails, etc 248 
 
 Spans, 25 ft. or less 258, 259 
 
 25 ft. or over 261,271,276 
 
 Spars, arrangement of 257 
 
 Splice, long 221 
 
 eye 222 
 
282 
 
 Index. 
 
 Far. 
 
 Splinter-proof for trenches 35 
 
 Stockade, advantages of, defini- 
 tion of 180 
 
 how destroyed 434, 451 
 
 kind of timber preferable for. 186 
 
 loopholes in 184 
 
 loopholes, when cut in 185 
 
 of vertical timbers 182 
 
 of same, square and round 
 
 timbers 183 
 
 of horizontal timber 187 
 
 Stockade, of R. R. iron, destroy- 
 ed how 434 
 
 when employed 181 
 
 work used for tambours and 
 
 caponiers 188 
 
 Stones in trenches, where placed 34 
 
 Straightening rails 407 
 
 Streams, unfordable, how passed 294 
 velocity of, how determined.. 296 
 
 width of. how determined 312 
 
 Strength of materials 249 
 
 of rope ....217, 218 
 
 Sub-drains 361 
 
 Suspension bridges 280-6 
 
 Switch, split and stub 384 
 
 Table of breaking loads 218 
 
 of constants "C" 253 
 
 of weights of materials 256 
 
 showing amounts of revetting 
 materials for 100 linear 
 
 feet of revetment 137 
 
 Tackle, description of 229 
 
 formula for power of , 235 
 
 power of 233-4 
 
 to prevent twisting 232 
 
 to round in, to overhaul 231 
 
 Tambour 147 
 
 stockade work used for 188 
 
 used in flanking buildings ... 199 
 
 Tasks (PI. 14, 16) 111, 112 
 
 laying out of 101 
 
 in constructing parallels and 
 
 approaches PI. 22 
 
 responsibility for completion 
 
 of 106 
 
 Telegraph messages 408 
 
 lines, how destroyed 420 
 
 Par. 
 
 Telephone, outpost cart for 418 
 
 Telford roads 363 
 
 Terreplein 74 
 
 Thickness of materials proof 
 
 against small arms 15 
 
 Ties, metal 379 
 
 wood 378 
 
 Timber Bridge, how destroyed 431 
 
 felled, removal of 45 
 
 kinds preferable for stockade 186 
 
 round for revetments 125 
 
 standing, removal of 43,44 
 
 Tools, carrying of by working 
 
 parties 108 
 
 cutting, intrenching used in 
 
 the field 41 
 
 taking of, by working parties.. 107 
 
 used in felling timber 44 
 
 Torpedo, U. S. bridge 432 
 
 Torpedoes, automatic 454 
 
 Trace, definition of 64 
 
 selection of 89 
 
 Transom, strength of 250 
 
 Traverse, definition of 68 
 
 method of determining height 
 
 of 93 
 
 Tread banquette 65 
 
 Treble sling bridge 277 
 
 Tree insulator and tie 415 
 
 Trees, cutting of .44, 45 
 
 how to fell with explosives 430 
 
 Trench 65 
 
 common, uses of, how made. . 156 
 
 drainage of 98 
 
 method of digging , 101 
 
 Trenches, advantages and disad- 
 vantages of 38 
 
 disguising location of 38 
 
 intervals in line of 34 
 
 kneeling or sitting 30 
 
 location of 33 
 
 loosening earth in front of 38 
 
 lying 29 
 
 standing 31 
 
 Troops, weight of on bridge 252 
 
 Trestles, capped 264 
 
 tie-block 263 
 
 two-legged 265 
 
 three-legged 266 
 
Par. 
 Trestles, continued. 
 
 four-legged 267 
 
 six-legged 262 
 
 Truss, king-post 272 
 
 queen-post 273 
 
 portable 279 
 
 Tunnels, how destroyed 446 
 
 repair of 406 
 
 Turntables, railroad 388 
 
 Unloading in ferrying 301 
 
 horses from R. R. cars.... 393, 394 
 wagons from cars , 896 
 
 Urinals 488,489 
 
 Velocity of streams, how deter- 
 
 ' mined.... 296 
 
 Village, advantages and disad- 
 vantages of for defense 206 
 
 artillery, where placed in de- 
 fense of 215 
 
 broadside, how defended 213 
 
 circular, how defended 214 
 
 cover for supports and re- 
 serves in 215 
 
 in defense of, precautions 
 
 necessary 205 
 
 defense of depends on 208 
 
 arrangements for defense of. 205 
 
 garrison of, how determined.. 211 
 
 objects in holding 207 
 
 salient, how defended 212 
 
 value of, for defense 205 
 
 arrangement for defense of, 
 
 how made 210 
 
 Wagon body ponton, construc- 
 
 struction of 324 
 
 Wagons, prepared for crossing 
 
 on ice 299 
 
 AValls, for double tiers of fire 167 
 
 discussion of as military ex- 
 pedients 161 
 
 loopholing 163-5 
 
 preparation of for defense 162 
 
 removal of 48 
 
 how destroyed 442, 451 
 
 Water, clarification of 476 
 
 drinking 465-9 
 
 filtering 480-1 
 
 Index. 283 
 
 Par. 
 Water, continued. 
 
 guarding 464 
 
 necessity of and amount re- 
 quired ...463-4 
 
 Water tables on roads 361 
 
 Watling 118 
 
 Weeds, removal of 47 
 
 Weight of materials 256 
 
 of rope 218 
 
 of troops on bridge 252 
 
 Wells, digging of 470-2 
 
 driven 473-4 
 
 Width of roads 858 
 
 Winch 240 
 
 Windlass, description of 241 
 
 Windbreaks for camps 500 
 
 Windows of buildings, how bar- 
 ricaded 197 
 
 Wire, connection of 428 
 
 entanglements, high, low, how 
 
 made : 52, 53 
 
 entanglements, how destroyed 449 
 how stretched, hanging of, 
 
 secured to 414 
 
 how strung across roads 411 
 
 how strung across streams . . . 415 
 
 telegraph 408 
 
 tie 413 
 
 Withes, making and use of 117 
 
 Woods, artillery in 179 
 
 communications in 177 
 
 cover in 176 
 
 lying beyond position 175 
 
 number of defenders of 179 
 
 preparation of edge of 174 
 
 2nd and 3rd lines in 178 
 
 Works, constructed by troops to 
 
 occupy 5 
 
 double line of 150 
 
 fixed types of necessary 6 
 
 groups of, intermediate, when 
 
 used 149 
 
 line of 148 
 
 advantages and principles of. 149 
 Works, field, conditions to be ful- 
 filled 62 
 
 calculation of cross section of 95 
 
 classification as to trace 83 
 
 defilade of . ^. 88, 89, 90, 91, 92 
 
1>84 
 
 Indkx. 
 
 Par. 
 Works, oontiiiued. 
 
 details of construction of.99, 100, 101 
 length of crest for assumed 
 
 garrison 100 
 
 open, closed, and half closed, 
 
 definitions, advantages and 
 
 disadvantages 8:1 
 
 continuous line of, cremaillere, 
 
 blunted redan, redan with 
 
 J'ar. 
 Works, continued 
 
 curtains, terraille, terraille 
 
 and redan, trace of 152 
 
 Working parties, extension of. 109, 110 
 
 organization of 105 
 
 when under fire Ill 
 
 Wye. R. R :!87 
 
 Zig-zag, direction of, length of. 15!) 
 extending along 155 
 

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