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40

W.O.

MANUAL

MILITAET EMlNEEIll]\Tx

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(5289) A 2

CONTENTS

Chapter.

Subject.

Page.

IT.

ITT.

IT.

YI.

YIL

VIII.

IX.

XI.

XII.

XIII.

XIV.

XV.

XVI.

XVII.

XVIII.

XIX.

XX.

XXI.

XXTI.
XXIII.

PAET I.
Peeltaitnabt

ElELD GeOMETUT . .
lNTRE>^CHiyG^ T03LS

WoEKiNG Parties and Execution of In-

trench5ients
Materials . .
Retetiments . .
Clearing the Foreground
Improvement of existing Coyer, Stockades,

&c. ..
Earthworks. .
Obstacles

Defence of Posts, Villages and Camps
Temporary Eoads ....
Knotting AND Lashings..
Military Bridges. .
Camping Arrangements..
Hasty Demolitions with Explosives.,

„ Demolition of Railways and Tele-
graphs without Explosives

PART II.

Strength of Materials and Buoyancy
Blocks and Tackles — Use of Spaiis ..
Erame and Cantilever Bridges, Framed

Trestles, Suspension Bridges, and Cask

Piers
Demolition Eoemulje and Working Party

Table, &c.
Roads— Boning and Levelling
Railways and Telegraphs

G-LOSSARY OF TeRMS

Index

5
10
12

14
17
23
25

26
31
41
44
51
52
55
68
78

101
107

109

lis

]2S
l;{7
]40

MMUAL OF MILITARY ENGINEERING.

(^Tliis book is divided into two parts. Officers should he
ihoroughly acquainted with the matter dealt icith in Fart I.
Part II contains information useful for reference.

The types of the various works described will vary according to
the conditions of time, labour, and material.

Officers and Non-commissioned Officers in charge of luorks
should, while bearing the principles in mind, learn to modify the
types according to local conditions.')

CHAPTER I.— PRELIMINARY.

{See also " Combined Training," 1905, Section 123, and
following sections.)

1. The object of fortification is to strengthen ground, and by Objects o!
thus economising the numbers of the defenders, to swell the fortifica-
force available for offensive movements, by which alone ^^°^'
decisive results can be obtained. This object is secured by
fulfilling, as far as possible, the following conditions : —

(a) The position to be defended must be chosen with due General
regard to tactical requirements, and with a view P^iiiciples.
to economising men ; its strong and weak points
must be carefully studied.
(6) The enemy in attacking should be exposed as much
as possible to the fire of the defenders during the
advance. To this end the foreground may require
more or less clearing,
(c) Every endeavour must be made to deceive the enemy
as to the strength and dispositions of the troops in
the defence, and as to the character of the defensive
works.

6 CHAPTER I. — PRELIMINARY.

(d) The defenders should be sheltered from the enemy's

fire, and as far as possible screened from liis view,
by natural or artificial cover, so arranged as to permit
the greatest possible development of rifle fire.

(e) The free movement of the attacking troops should

be hindered by leaving or creating obstacles to detain
them under fire or to break their order of attack.

(/) The free movement of the defenders should be assisted
by improving communications within their position,
and clearing the way for counter attack.

Shortly stated these principles in order of importance are : —

(a) Choice of ground.

(b) Clearance of foreground,

{d) Provision of cover.

(e) Creation of obstacles.

(/) Improvement of communications.

The above are dealt with in detail in subsequent chapters.

2. A thorough knowledge of the fire effect of all arms is
necessary, in order to design good defence Avorks,

Rifle fire, 3, Modern military rifles are sighted to about 2,800 yards.
The slope of descent of the bullet varies from about -^^ at
1,000 yards to ^ at 2,800 yards.

Height oi: The heights over which an average man can fire on level
line of ground are : —

^^^' Lying down 1' 0''

Kneeling 3' 0^'

Standing 4' 3'^ to 4' <6"

These heights must be adjusted to suit different men ana
varying inclinations of ground.

CHAPTER I. — PRELIMINARY.

4. The following table gives the thickness in various materials-
proof against modern rifle bullets at foint blank range : —

Material.

Thickness
proof.

Remarks.

Clay

5 ft.

Varies greatly. This is maxi-
mum for greas7 clay.

Earth, free from stones

3 ft.

Ramming earth reduces its

(unrammed)

resisting power.

Sand

2 ft. 6 ins.

Rather more than enough.
Very high velocity buUets
have less penetration in
sand at short than at

medium ranges.

Sand between boar Js

IS ins.

Brickwork . . . . . .

9 ins.

If well built.

Soft wood, e.g., fir, across

48 ins.

24 ins. proof at 500 yds.

grain

Hard wocd, e.g., oak, across

27 ins.

15 ins. proof at 500 yds.

grain

Wrought iron or mild steel

Jin.

Hardened steel plate

iin.

yV in. proof at 600 yds.

Special hard steel ..

4 in.

Shingle ..

6 ins.

Coal

15 ins.

Snow

About 8 ft.

5. The usual projectiles for field artillery are shrapnel from Field
field guns, and shrapnel and common shell filled with higr artillerj.
explosive from field howitzers.

Shrapnel can be used from field guns at ranges up to about
6,000 yards.

The slope of descent of the projectiles of field guns varies
from ^ at 1,500 yards to J at 4,000 yards, but howitzer
projectiles have angles of descent up to \.

6. The penetration of shrapnel balls is considerablv less Penetra-
than that of small-bore rifle bullets, but shrapnel with percussion tion of
fuzes can be used with considerable effect against troops behind ^^^\1^^^.^'
waUs. projectiles.

Several foreign nations have introduced common shell filled
with some high explosive for use with field guns. The special
feature of such shell is that, on bursting, they break up into a

CHAPTER I. — PRELIMINARY.

Field
lio\\ il zerp.

Heavy
gnis.

Modern
aitilleiy.

Ranges.

very large number of fragments wHch are driven in all
directions. They are not so effective as well burst shrapnel.

7. Field howitzers, firing common shell and shrapnel, have
now been introduced into the service of most nations. They
are light pieces of artillery, firing comparatively heavy shell,
with low charges at high elevation, and in consequence possess
gocd searching power*

No practicable amount of extemporised cover, except as
in Sec. 73, will keep out a howitzer common shell. The effect
of the burst is very powerful, not merely from the fragments
of the shell, but also from the blast and the fumes of the
explosive ; but this effect is very local, and slight cover will
suffice against the splinters.

80 Heavy guns up to 6-inch have been used in the field
and will probably be met with in future. They are long-
ranging, but their searching power is little greater than that of
field guns.

9. The object of modern artillery is to reach the defenders
of a parapet by means of fragments of projectiles burst in the
right position, and not by breeching the parapet with the pro-
jectile itself. An occasional sheU may strike and penetrate
the parapet, but in the case of a shrapnel shell the damage
to the parapet wiU be trifling, while in the case of a howitzer
shell filled with high explosive, the effect will be no worse
on a thin parapet than on a thick one. Thus it is useless to
spend time and labour on making a thick parapet to keep
out the actual shell. Against such fire, concealment is of
greatest importance.

Plate 1 gives some idea of the effect of bursting shells.

10. The following table (taken from " Combined Training,"
1905) gives the various ranges of the different weapons : —

Terms applied to
ranges.

Rifle.

Field
Artillery.

Keavy

Artillery.

Distant
Long

Effective . .
Decisive

Yards.

2,800-2,000
2,000-1,400

1,400-eoo

coo and
under.

Yards.

6,000-4,500

4,500-3,500

3,500-2,000

2,000 and

under.

Yards.

10,000-6,000

6,000-4,000

4,000-2,500

2,500 and

under.

riai^, /.

Veiier&Sr^hflm. LJ* Li itio. London."

Opposite pou^e S.

CHAPTER I. — PRELIMINARY. 9

The extreme width of the area of ground struck by the
bullets of an effective shrapnel is about 25 yards.

The limit of the forward effect of shrapnel at effective range
is about 300 yards.

The radius of the explosion of a high explosive shell is
about 25 yards.

11. The follo^ving terms are used with reference to artillery Matures
and rifle fire :— of ^ire-

High Angle Fire. — Fire from guns and howitzers at all

angles of elevation exceeding 25°.
Frontal Fire. — When the line of fire is perpendicular to the

front of the target.
Oblique Fire. — AVhen the line of fire is inclined to the front

of the target.
Enfilade Fire. — Fire which sweeps a line of troops or

defences from a flank.
Reverse Fire. — When the rear instead of the front of the
target is fired at.

CHAPTER II.— FIELD GEOMETRY.

12. Before proceeding to the more technical portion of
military engineering, it is as well to understand some of the
simplest applications of geometry to the laying out of field
defences.
Slopes. Slopes are usually described by fractions, in which the

numerator expresses the height, and the denominator the base
of the slope.

Thus, in Fig. 2, Pi. 2, the vertical height, B C, is jr of the
horizontal distance, A B. The slope A C would, therefore, be
called a slope of ^ (verbally, one in six).

In Fig. 1, the vertical height B C is four times as great as the
horizontal distance A B. The slope A C is called -i (verbally,
four in one, or four over one).

Slopes are sometimes expressed in degrees. A good rough
rule for converting degrees of slopes into fractions, or the
reverse, is to divide 60 by the number of degrees expressing the
slope, the result gives the denominator of the fraction whose
numerator is 1, e.g., 5^ slope = ^i^"' ^^ 1 ^^ ^- slope.

N.B. — This formula should not be used for slopes steeper
than 30^

To lay out 13. To lay out a right angle. Let X be a point in a given
a right straight line A B (Fig. 3), from which it is required to set oS a
*"gl^- right angle.

Take any point C in A B, and drive in pickets at C and X.
Take any convenient length of tape C D X, and make loops
at either end, and find its centre D by doubling it. Xow place
the two loops over C and X and stretch the tape taut into the
position C D X. Take D X off the picket at X and turn it
round till it comes into the position D E, in prolongation of
C D. Join E X, which gives the right angle required.

2nd Method. — From X measure off a distance of 4 units
X C along A B (Fig. 4). Take a piece of line or tape 8 units
long, and apply one end to the point X, and the other to the
point C ; find a point in the tape 3 units from X, and seizing
it at this point, draw the bight out to D, till the line is taught,
then C X D is a right angle. This method is founded on the

I^lajt€> Z,

Fi^.1.^

c Field Geometry.

A C

J^ff.5.[

^x ^^ ^

c :b

-'C SB

■<a4Me ^.os

W«J{f r * Gr«h«m. Lr* Litho. LoiMlon.
Opposite pcu^e'iO

CHAPTER II. — FIELD GEOMETRY. 11

fact that in any triangle whose sides are in proportion of
3, 4 and 5, the angle contained between the two shorter sides
is a right angle.

14. To trace a perpendicular to a given hne from a point To trace
outside. Let X be the point outside the line A B (Fig. 5), perpendi-
f rom which it is required to draw a perpendicular to that line. ^ [ ^^"^
Take a tape or cord longer than the perpendicular will be ; fix outside a
one end at X, and stretching it taut, swing it round so that the given line,
other end shall cut A B in C. Drive in a peg at C, find D, the
middle point of C X. With D as centre, swing D X or D C

round to the position D E, cutting A B in E. Join X E, then
X E is at right angles to xV B.

15. To lay off an angle of 60"^ or 120^. Let X be the point To lay ofe
in the line A B (Fig. 6) from which it is required to lay off an angles of ^
angle of 60°. Take any point C in A B at a convenient distance o^'l^O .
from X, and towards that end of the line from which the angle

of 60° is desired to be drawn. Take a tape or cord twice the
length of X C, and fasten the ends to X and C. Seize it by the
middle point and draw the bight out taut to E. Then the
angle E X C is 60° and A X E is 120°.

16. To bisect a given angle. Let A B C be the angle which To bisect
it is required to bisect (Fig. 7). On B A and B C, mark points ^ ^'^J^^
D and E at equal distances from B. Find by means of a ^^^ ®'
tape or cord a point F equidistant from D and E. Join B F.

Then B F bisects the angle A B C.

17. To lay out an angle equal to a given angle. Let X be the To lay out
point in the straight line A B (Fig. 8), from which it is desired ^^ ^^§1®
to lay off an angle equal to the angle DEC. Fix the points ^^^^ *^
D and C at any convenient distance from E, and from the an't^le.
point X measure X G, equal to E C. Then from the point X

as centre, and a distance equal to E D as radius, and from the
point G as centre, and a distance equal to C D as radius,
describe arcs, intersecting at F. Join X F. The angle F X G
is equal to the given angle DEC.

18. To find the distance between any two points A and B Tofmdtbe
when it cannot be measured directly. From B (Fig. 9) lay off (distance
the line B D at any convenient angle, D being at any con- ^^tTwo

CHAPTER III. — INTPvEInCHIXG TOOLS.

points
when it
cannot be
measured
directly.

vcnient distance. In B D select a point C so that B C is some
multiple of C D. From D lay off the angle B D F equal to the
angle A B D, and on the opposite side of the line B D. Make
D E of such a length that the point E is in line vs-ith A and C.

Then A B : B C : : D E : C D,
BC X DE

or AB

as shown in PI. 2.

CHAPTER III.— IXTREXCHING TOOLS.

Tools

Use of
tools.

19. The service intrenching and cutting tools are shown on
Plates 3 and 4. It is well to note the dimensions, as
they are useful in laying out and executing work.

A heavy pick with an 8-lb. head has been sealed, and can be
obtained from Ordnance Store if heav3' work is expected.

Only a smaU proportion of spades are carried, as they
are of little use in the field. They are employed for cut-
ting sods, and for digging generally when a pick-axe is not
required.

20. For safety the pick must be used working front and rear,
and never sideways.

Before striking the pick into the ground it should be raised
well above the head with both hands. In bringing it do^vn, the
helve should slide through the hand nearest to the head, and
the weight of the pick should be employed to help in the work.

The shovel is used right or left handed. Xav\Tes make
gTeat use of the thigh in thrusting the shovel under the loosened
earth.

In throwing earth from the shovel there should be no
jerk, the left (or right) hand m^ust be allowed to slide freely
up the handle, otherwise the earth will scatter.

J^ta-teS

Intrenching Tools

*3*

1 .

Ft^.i.
SpoudUMf^ni 5Ujs Woxs. K ;^

Fs.5.
Crowhar 1a Ihs

S- 6'

*«06 ■ 05

Wel'trr & Grflhdti L'f Lirf^O London

Opposrfje JiCiriie JZ .

FLr.t^ 4-

CuTT! NG Tools

Aj-e. ■FeZUri.g , wer-ffh^ 6li^ 7oxs.

2^:5

BUI Nook

^2.7^

^«°^-zn.4!/ 7re^s

Ivff 6 .
Gre<it/ Anver-icarv Croas-cut^Scm weiglU Olbs. loxs.

fhk.

•' liitjrfi

^-^nuwfwu./iJ;:^.,^

Wcller & Graham. Lr^ Litha London.

7b foll^tvplcLU3.

CHAPTER III. — INTRENCHING TOOLS.

■The following tools will probablv bo carried in the field Tntrench-

bv remmental transport, but see Field Service Manuals : — "''? ^°^^
^ ^ cutting

tools.

•

•^

Royal
Engineers.

Infantry.

Tools.

£,

o
O

•- 5

%
'^

(a) latrenchinr; Tools.

Shovels

144

100

222

220

Spades

—

_:-

— ■

Axes, pick

100

148

110

(5) Cutting Tools.

Axes, felling

hand

—

— .

—

Bill-hooks

Saws, hand

3t5

,, cro's-cut

—

Reaping hooks

Crowhars

Guncotton (including primers)

lbs.

i-
1

ieoei

32CJ

The above numbers do not include wagon equipments.

Note. — G.S. wagon with headquarters of an Infantry
Brigade carries : —

Picks 80

Shovels 120

Crowbars . . . . . . 12

Reliefs.

Tasks.

Detail of

■working

parties.

Size of

tasks.

Balancing
parapet
and ex-
cavations.

CHAPTER IV.— WORKING PARTIES AND EXECU-
TION OF INTRENCHMENTS.

21. In digging intrenchments for all except the smallest
works, the working parties are not kept continuously at work,
but are changed at intervals, thus dividing the total time into
periods called reliefs. As regards the length of rdiejs a great
deal depends upon the nature of the work, the total time it
will take, and the climate. Also the question must be con-
sidered as to whether the work has to be hurried through, and
whether it can be carried on by night as well as by day. Short
reliefs are best, and as a rule it will be found that a four hours
relief (actual digging) is quite long enough for the infantry
soldier. Six hours reliefs may occasionally be resorted to.

A task is the amount of work a man has to do in one
relief.

Too much pains cannot be taken in the preliminary details
of working parties, so that they may arrive at the site of
their work, ready provided with tools, their tasks clearly
defined, and the men in such formation as will admit of
their ready distribution on the work. Delay and noise is
thus avoided, and the chance of confusion during night
work reduced to a minimum.

In ordinary easy soil the average untrained soldier should
excavate with service tools {see Pi. 3, Figs. 1 and 3) 30 cubic
feet in one hour, or 80 cubic feet in a four-hour relief.

If the soil is very easy these rates may be increased, and
vice versa ; in hard stony ground it may be reduced by 50
per cent.

These rates hold up to a maximum horizontal throw of
12 feet, combined with a lift out of a trench 4 feet deep.

22. As the earth required for the parapet of a large field work
is obtained from the excavations (ditch and trench), the areas
of the sections across the parapet and excavation must be
roughly balanced.

PI. 5, Fig. 1, gives an example of a section of a parapet
with high command, the successive reliefs (with their tasks)
necessary for the execution of the work being shown.

Figures shown thus [" 36 ] denote the area of the excava-
tion or parapet in square feet.

Plxit4 .5.

BALANCING PARAPET &. EXCAVATION

z±^-A \ «.

TASKS

I ReJjrj&f' 76 ctcij5rjc feet

u . ,,.-. 7;^ .. .-

3ir 3S% ,, .. „ -.

TASKS
JT — f , — »>.^^ - ,, — , , --

PROFILING

^r^.^,

Jhter^ior- csrss

''////w//////w/Mmmm^,

s/ae .s OS.

Wfiier&Grahan.L'* UrhoLoodon

Opposite pa^ tS.

CHAPTER IV. — WORKING PARTIES, ETC. 15

23. Tracing a work consists in laying out so much of its plan Tracing,
on the ground as is necessary to guide the distribution of

the working parties. This may be done by a mark on the
ground, or by tapes.

In hasty defence work tracing with a tape is usually only
necessary for night work.

24. When making works of high command, profiles should be Profiling,
put up to guide the construction of the parapet. {See PI. 5.)

For high profiles it is best to drive stout pickets into the
ground at the position of the verticals, construct the profile
bodily to a straight line, lying flat on the ground, and then
up-end it, and nail it to the pickets on a level line.

Profiles are laid out at right angles to the crest line. They
should be placed at intervals of about 30 feet, two at least being
required for each face near the angles.

High profiles should be secured by stays or light guys, or
they are liable to be blown down.

25. For all intrenchments the normal distance apart at Orgauisa.
which the men are spaced for work is two paces (5 feet). ^^^^ 9^
This can be reduced, if necessary, to 4 feet, but it cramps the "^*^ff^"S
diggers.

Task work is better than working for a fixed time. In
arranging tasks it is better to under estimate the men's powers
in order to avoid incomplete tasks.

In arranging reliefs, the following rules should, if possible,
be adhered to : —

(1) The second and succeeding reliefs should have less

earth to excavate than the first, as the diggers have
further to throw.

(2) If fossible, each relief should leave a vertical face

of earth for the next relief to commence upon. For
instance, in PL 5, Fig. 1, the dividing line between
the reliefs is vertical and not horizontal.
26. _A party of the necessary strength for the work in hand. Detailing
including a reserve of one-tenth, having been demanded, working
should be detailed from a company, battalion, brigade, or P^^'^^^s.
division, and not formed of detachments from difierent com-
panies and corps.

16 CHAPTER IV. — V/ORKING PARTIES, ETC.

The party is then marched to the tool depot to get their
tools, which should be ready laid out, according to the detail
of the several parties, either in rows or in heaps, the men in
the former case filing on the rows and taking up a pick in
the left hand and a shovel in the right, or filing between the
heaps and receiving the tools in the same order in passing.

For extending men for work, see " Infantrv Trainiog,'*
1905, p. 96.

If the party be large and the work of a complicated nature,
such as a redoubt, the men should be divided into detachments,
each under a superintendent, corresponding to definite portions
of the work, formed in column at some distance from the site,
and successively extended along the line, driving in their picks
on the left of their tasks, and laying down their shovels along
the front. It is sometimes advisable, in order to save time
in extending, to keep a separate detachment for distributing
on the excavations at the angles.

No work must be commenced till the distribution of the whole
is complete, as it is difficult to remedy mistakes when work has
once begun, the subsequent shifting of men invariably tending
to confusion and possibly loss of tools, clothing and accoutre-
ments.
Double When the men available greatly exceed the tools in number,

manning i^, j^^y be advisable to tell off tw^o men to each set of tools, and
*° so complete the work in about two-thirds of the ordinary

time.

Superintendents should be relieved at alternate hours to
the working parties, to ensure continuity in work.

When the distance that the earth has to be thrown is too
great for the diggers to deposit it in its final position in one
throw, shovellers wiU be necessary as well as diggers.

Methods 27. Diggers should commence on the left of their tasks, in

of execu- order to incommode each other as little as possible.

tmg tasks. j^ excavating V-shaped ditches the slopes should not be

formed until the last relief, rectangular portions being taken

out first.
If not under fire the earth first excavated should be furthest

thrown.

CHAPTER V. — MATERIALS. 17

In making fire-trenches the men should try to get cover as
soon as possible. Sods and lumps of earth should be used
for revetting the interior slope, which must be made as nearly
vertical as possible, the revetting being carried on with the
parapet.

CHAPTER v.— MATERIALS.

For approximate time required for carrying out work referred to
in this chapter, with labour and tools, see table, p. 120.

28. The materials, which are mostly available for the con- Earth,
struction of field defences are earth, st-- nes, timber and
brushwood, while railway plant, iron sheeting, wire barbed

and plain, &c., may often be obtained. Of these materials
earth is the most valuable as well as the most generally used.

For the purpose of field fortification, earth is usually pro-
cured from the trenches dug as near as possible to the place
where it is to be used.

The steepest slopes at which thrown-up earth will stand
is about 45° or \.

29. Sods are used for revetments and also to form walls in Sods,
special cases. They should, if possible, be cut from meadows
growing thick grass. Each sod should be about 18 inches
long, 9 inches broad (these dimensions depending, however,

on the width of the spade) and 4| inches thick.

30. Stones may be employed to form rough walls in places stones.
where digging is difficult or impossible. A well-built rubble

wall, 12 to 18 inches thick, will keep out bullets, this thickness
being necessary to avoid having any " through " joints.

Two such walls about 10 feet apart afford good protection
against artillery fire, the outer wall, which should be at least
2 feet thick, serving to burst the shell.

31. Timber is used in the construction of bridges, huts, Timber,
splinter-proofs, stockades, abatis, &c.

(5289) B

18 CHAPTER V. — MATERIALS.

Felling 32. The tools employed for felling timber are the felling axe,

Timber. ^|^g hand axe, the cross-cut saw and the Jiand saw (PI. 4).
Of these the felling axe in the hands of an experienced work-
man is, probably, the best of all. The hand axe is only
suitable for felling small trees not exceeding 12 inches to
15 inches in diameter, but it may be employed with advan-
tage when men practised in the use of the felling axe are
not available, as it requires little or no skill in handling.

The cross-cut saw or the hand savr may also be used, the latter
with small trees only, provided that measures are taken, by
wedging or otherwise, to prevent the weight of the tree from
jamming. Inexperienced men can use the cross-cut saw more
easily and safely than the axe, and can cut more quickly with it.
When convenient, it is best to fell a tree in the direction of its
natural inclination. In using the felling axe, the tree should be
first attacked on the side on which it is required to fall, a rope
being employed, if necessar)-, to pull it over, as, for instance,
when the natural inclination is not in the required direction.
When the tree has been cut into as far as the centre, or a little
beyond it, the workman should change over to the opposite side
and commence cutting about 4 or 5 inches above the former cut
until the tree falls. The cuts should be as shown in Fig. 4,
PL 4, where the arrow indicates the direction in which the
tree is required to fall. With beginners, or when it is not
important to save timber, and when there is no objection
to leaving the cover which high stumps afford, the point a
should be the height of the hip, h c should be about three-fourths
the diameter of the tree.

It may sometimes be convenient to employ both the saw
and the axe to cut down a tree. In such cases the axe should
be used on the side towards which the tree is to fall, and the
saw en the opposite side.

The teeth of all saws used for cutting down timber should
be set wide.
Cutting 33. Brushwood is much used in military engineering for

!!L"!^" roadmaking and revetting purposes, and for the construction
of gabions, fascines, hurdles, &c.

WiUow, birch, ash, Spanish chestnut and hazel are the
most suitable kinds, and work best if cut w^hen the leaf is off.

ood.

Thff^' G.

Tiq.Z

or'JBnttorL

Brushwood.

JifeZfvoOi of 7>iftdz7i^^r*itsJuvood

^zy.;. /rj) JJVB

^^.5

4^06 S. 05

.eilerSrGraham. L'* Lirho, London
Opposite pajge J 9

CHAPTER V. — MATERIALS. ID

As a rough rule it may be taken that 1,000 square yards of
brushwood, 0 years old, make up three G.S. wagon loads.

34. Withes, for binding purposes, in lieu of wire spun yarn, Withes.
&c., are made of pliable wood, such as willow and hazel. They
should be 6 feet to 7 feet long, | inch in diameter, and made
pliable by being well twisted, the thin end being placed under

the left foot, and the rod twisted with the hands, avoiding
kinks. If the rod is stiff a smaU. piece of stick, lashed across
the butt, will be of use in twisting it (PL 6).

35. A fascine is a long faggot tightly packed and carefully Fascines,
bound, used in revetments, for foundations of roads in marshy

sites, and for many other purposes. The usual dimensions
are 18 feet long and 9 inches in diameter. It is made in a
cradle of trestles placed at a uniform level (PL 7, Figs. 6
and 9). The brushwood, trimmed if possible, is laid in the
cradle, projecting about 1 foot 6 inches beyond the outside
trestles, and adjusted so that there may be no weak place.
Crooked rods must be half sawn through and straightened.

The fascine is then gauged with the choker (Fig. 7), Choker,
which consists of two wooden levers, 4 feet long, connected
at 18 inches from their ends by a chain 4 feet long, provided
with two gauge rings, 28 inches apart, corresponding to the
circumference of the fascine.

To use it, two men, standing one on each side, place the
centre of the chain under the fascine with the short ends of
the levers uppermost, cross the levers to each other over the
fascine with the short ends down, and bear down on the long
ends until the gauge rings meet.

Binding must be commenced at one end. The first binding Binding,
(of we, spun yarn hoops or withes) is put on 3 inches
beyond the outside trestle, and the remainder (12 in all) at
intervals of about 18 inches. This admits of the fascine being
cut, if required, into 9 feet or 6 feet lengths. The ends of the
fascine are sawn off 9 inches beyond the outside bindings.

In all cases the fascine must be choked close up to the
position of the binding while the latter is being put on.

With withes an eye is formed at the tip, the withe put on With
under the fascine, the ends brought up, the butt passed through withes.
the eye, turned back and twisted round itself (Fig. 5).

(5289) -B 2

Piclvets.

Gabions.

Brush-
wood
gabion.

CHAPTER V. — MATERIALS.

Length.

Diameter.

feet ins.

ins. ins.

3 6

ftol

2 6

li » li

6 6

3 „ 4

3 6

1 „ 2

1 6

1 „ U

5 0

li „ 2*'

2 6

1 „ li

1 6

h „ 1

With spun yarn the centre is found and laid on the fascln^
and the yarn is then passed twice round the fascine, haule
taut, and fastened off with a reef knot.

Both withes and yarn are apt to perish.

Wire is laid on like the yarn, passed twice round, haule
taut, the ends t\^asted together and tucked in ; 14 gaug
is a convenient size.

A piece of hoop iron may be used for binding. It should b
31 inches long, with notches cut at opposite vsides, and 2.
inches apart. The iron is passed round the fascine, and th
notches hitched together (Fig. 8).

36. Pickets are made from brushwood for various purposes

The following dimensions are useful for reference : —

For gabions
fascines
fascine cradles
hurdles
tracing

high wire entanglement
low wire entanglement
sodwork

37. Gabions are cylinders open at both ends, which, when
standing on one end and filled with earth, make a strong
revetment.

For dimensions see PL 8.

They may be made of almost any material capable of beina
bent or woven into a cylindrical form, such as brushwood,^
canvas, sheet iron, ware netting, &c. Their employment in
the future is likely to be more limited than in the past, as
revetments are as a rule lower, and so simpler forms of support
will suffice.

38. To make a brushwood gabion, a circle of 10| inches radius
is traced on level ground, and an even number of pickets,
usually 10 or 12, driven at equal intervals round the inside
of the circumference {see Fig. 1).

The pickets are 3 feet 6 inches high, | inch to 1 inch in
diameter, and must be driven with the thick and thin end
alternately downwards.

PlaJte 7

Brushwood.

Fascines

:Fiff.7.

^a^'czne. Choicer^,

M-PO->^.

\ ^ ' . >,<

<!> s^,mf4,.^ ,..> .. .o

WelleriGrahsff'. L" Lirtxi Lerdw

Oppas/Lte pcx^e 20.

Plnte 8

Brusjiwood.

Gabions.
S&i/ym' yj'ithj \vir& or' spuny i/oc/yz/

Tiff. /. Tzff.Z.

Tiff. 4^.

jyl ||

HI HI i [H

'H3

Ti.j.5.

Tig. 6.

Tz^.S

J^-9

^....2f)"-->

We<le'i< C-rgham. I" Lif'^oLooon

Ojjposite^ p<x^&Z1 .

CHAPTER V. — MATERIALS. 21

The web is constructed by a process called waling, as Waling,
follows : —

Three rods well trimmed are placed with their butt ends
inside three adjacent pickets (Fig. 1). The first rod is passed
over the other two, outside the two adjacent pickets, and inside
the third, the second and third rods are similarly treated, and
the process continued. When introducing a fresh rod in place
of one that is coming to an end, the two must be laid together
for a few inches and worked as one rod.

The web must be close, even and well pressed down, the
<limensions strictly maintained by frequent gauging, and the
pickets kept upright and in their proper places, otherwise
the gabion will become either crooked or funnel-shaped.

When the web has reached a height of 2 feet 6 inches, Pairing,
two pairing rods are put on as follows : — The rods must be
9 feet long, well twisted (like withes) and pointed at the butt
ends, which are driven down into the web at its lowest point
on either side of one of the pickets, the rods are then passed
alternately over and under each other, and inside and outside
the pickets (being well twisted during the operation), and
finished off and driven down the web on either side of the
picket next beyond that at which the pairing was commenced.

The pairing rods are then sewn down to the web at Sewing,
four equal intervals, either with wire, spun yarn, or withes.
If the latter -are used they should be about 6 feet long and well
twisted. The first sewing is placed where the pairing rods
are double, the butt end is passed through the web from the
outside 7 inches below the top and turned down inside ; the
withe brought over the top, down inside, through the web
above the old place, do^vn outside, through the web again
7 inches lower down, back through the web, clasping the butt
end in passing down outside, back through the web another
7 inches down, and finished off with two half hitches round the
butt end above the clasping.

The gabion is then reversed, pairing rods put on at the bottom
and sewn in four places, the sewings alternating with those
already put on. A carrying picket must then be driven through
the web.

Forked pickets (Fig. 6) driven well down into the web
may sometimes be used instead of sewing.

CHAPTER v. — MATERIALS.

Jones'
gabions.

Hurdles.

Willesdtn 39. Willesden paper band gabions are an article of store,
paper Each gabion consists of 10 bands, 3 inches wide, fastened at

ga ions. ^^^ ^^^^ -^^^ ^^^^^ copper cUps. (Pb 8, Figs. 8 and 9.)

To make it, lay a band ready fastened in the form of a circle
on the ground. Drive the pickets, 10 in number, round it
alternately inside and outside, sHp a second band over the
tops of the pickets, alternating with the first band, and press
it half-way down to keep the pickets steady, until the third
band is on, when they may be pressed down to the bottom,
and the remaining seven bands put on. All the joints should
be kept behind two adjacent pickets. A thin carrying picket
can be driven through the web. The top and bottom bands
should be nailed to the pickets.

Jones' steel band gabions are still articles of store, but no
more will be made. They are made up similarly to Willesden
paper gabions.

40. Hurdles, unless for a special object, are usually made
6 feet long and 2 feet 9 inches high in the web, thus correspond-
ing to the height of a gabion {see PI. 9).

They are useful for revetments, huts and temporary roadways.

A line 6 feet long is marked on the ground, and divided
into nine equal parts, and a picket (about 3 feet 6 inches long
and from 1 inch to 2 inches in diameter) driven in at each
division, the two outside ones being somewhat stouter and
longer ; the web is then constructed by randing.
Ranfling. Randing is worked with single rods, and is commenced
in the centre {see Fig. 1). The rod is taken alternate sides of
the pickets, twisted round the end pickets, and woven back
to the centre. A fresh rod must overlap by several pickets
the one which it supplants.

Pairing rods are used in the centre and at both ends of the
web, which is usually se^vn top and bottom in three places.

The operation of slewing is the same as randing, two or
three rods being worked simultaneously ; it makes weaker
work than randing.

Slewing.

JL L4AJL4' y

Brush wood

Tiff J.

CcfTTurve^t^cerfzepvi? ofa^ 6fP Hur-clle..

7 to 2/ ISzuTclLe^ o/^.JBr7zs7iAA^6o(L

igoe ." OS.

Ojjrposxte page 22- .

CHAPTER VI.— REVETMENTS.

41. A revetment is a retaining wall used for supporting
earth at a steeper slope than that at which it would naturally
stand.

The following are the revetments most in use in the field : —

42. Gabion. — This is one of the best that can be used when a Gabion
considerable height of parapet has to be dealt with, but for revetment,
breastworks gabions are extravagant of material. They are
usually placed at a slope of \. This tilt may be obtained by
resting their outer edges on a fascine sunk 3 inches into the
ground (PI. 10, Fig. 1), or in any other way.

For high parapets two fascines are generally interpolated
between the rows of gabions, and in this case it is advisable
to anchor the gabions \\\i\\ wire to stakes, fascines, or logs
buried in the parapet. (Figs. 3 and 1.)

43. Fascines. — Fascines make a poor revetment by themselves, Fasc ne
and their use is generally confined to revetting steps. They ^^^e^ment.
should be well picketed down.

44. Hurdles. — Hurdles form some of the most useful forms of Hurdle
revetment, either in the form of ready-made hurdles, or revetment,
continuous hurdle revetment constructed simultaneously

with the parapet. In either case the slope is built
at \, and frequent anchoring is essential. Stretching of
fastenings, &c., due to weight of earth in the parapet, will
bring the hurdle to a slope of \, as shown in PL 10, Fig. 7.
In continuous hurdlework the web is formed by randing or
slewing, each pair of men having 10 feet or 12 feet of revetment
as their task time, J to | of an hour. They must work in
their rods with the men on either side. (Fig. 7.)

45. Brushwood. — This is a rapidly made and useful revetment. Brush-
Stakes are driven in at a slope of about f , at from 1 foot to wood

2 feet apart, and anchored back. As the parapet rises, loose revetment,
brushwood (or ferns, reeds, straw, &c.) is filled in between
the stakes and the parapet. (Fig. 2.)

46. Sandbag revetment is made at a slope of f with alternate Sandbag
rows of headers and stretchers (the former with the chokes, revetment,
the latter with the seams turned into the parapet), breaking

joint (Fig. 5). The bags must be laid at right angles to the

24 CHAPTER VI. —REVETMENTS.

slojie, .ind not liorizontally or the revetment may slide. Thev
should be not more than about three-quarters full, and should
be well beaten when placed in position. Two men build, and
if supplied with sandbags by carriers and fillers, will lay about
70 bags an hour ; 1 cubic \Hird of earth fills about 50 bags.
Sod 47. Sod revetment is built at a slope of |. The sods should

revetment. \^fy ^^^^ jg inches long, 9 inches wide, and not more than i\ inches
thick, with a sharpened spade or sod-cutter (Fig. 8).

They must be laid in alternate rows of headers and stretchers,

grass downwards, breaking joint, and at right angles to the

slope, with two rows of sods in each stretcher course. The

top layer should be laid with grass upwards, and all headers.

They should be bedded and backed by fine earth well rammed.

For superior work the sods should not exceed 3 inches in

thickness ; and a picket should be driven through each sod.

Cleit fir pickets are better than round, which split the sods.

Two builders should lay 70 to 100 sods an hour.

Timber 48. Timber revetment may be made by driving strong stakes

revetment j^^q ^]^g ground, placing planking behind them, and filling in

with earth. The slope wall depend on the strength of the

timber, f will generally be safe. The stakes should be anchored.

Planks should never be used for revetments where they will

be exposed to the fire of high explosive shells.

Willesclen 49. Willesden canvas. — This is kept as an article of store,

canvas [^ \ojig strips about 3 feet wide. For use, stout pickets should

■ be driven from 12 inches to 18 inches apart and anchored.

The canvas will then be stretched between these and the

parapet, being laced with wire to the pickets top and bottom

at about 6 feet intervals (Fig. 6).

Wire 50. Wire netting with stakes passed in and out of the meshes

netting ^j^^j anchored back forms a good revetment in soils which are

revetment. j. , i

not too sandy.

All revetments of parapets intended for musketry fire
should be finished off with one or two courses of sods or sand-
bags, where available.

For estimate of material required for revetments, see table^
p. 120

vuue. ;o.

Revetmep^ts

Brushwooo

OANHBAGS

^'.e:

CcLnx^aJi ^^' ^-

Fig.Q

Section^

HUR-DLE

4soe.z OS.

Welter 4 Graham l'"^ Litbo. London

CHAPTER VII.-CLEAKING THE FOREGROUND.

For estimate of time and labour required, see table, f. 120.

51. In most cases a certain amount of clearing will have to GenerMl
be done in front of a defensive position. The object should pi-iuciples.
be to secure for the defenders the full use of their weapons
within effective range, while at the same time leaving intact

or improving all existing obstacles which would impede the
free employment of the weapons of the enemy and obstruct
or break up his attack. When an active defence is contem-
plated (which would be the general rule) the obstacles left should
be such as not to interfere with counter-attack. In clearing Screens,
the foreground, the value of leaving screens to hide the
defenders' movements must be considered [see Chap. VIII,
Sec. 63).

It is difficult to make exact estimates of time required
to clear ground, as difficulties cannot be foreseen. The table
on p. 120 can only be taken as a rough guide for estimating
working parties.

It will be advisable to start the clearing from the position
and work forward as time permits.

Hollows and unseen ground, which would give an enemy's
troops shelter at points dangerously near the position, may
be filled up with abatis, or debris of walls, &c.

Large scattered trees give less cover when standing than if
cut down, and may sometimes be useful as range marks.

Thick brushwood, especially in the case of some tropical
growths, forms a very effective obstacle, which should only
be cleared away in accordance with the principles above laid
down. Thus, in place of making a general clearance, portions
may frequently be left with advantage, both to deny special
points to an enemy and to break up his attack, or to compel
the adoption of particular lines of advance (the portions cut
down may often be formed into an obstacle among the parts
left standing).

52. Hedges which interfere with the defenders' fire or screen Hedges,
the attack, must be removed.

2G CHAPTER VIII. — IMPROVEMENT OF EXISTING COVER, ETC.

The clearance of those perpendicular to the front is of less

importance than that of those parallel to the front.

Walls and 53. Walls can be knocked down by a part of men iisina a

buildings, trunk cf a tree or a railway iron as a battering ram. Low

buildings may be similarly treated. If high, they must be

blown down and the ruins levelled, as far as possible, so as

CHAPTER VIII.— IMPROVEMENT OF EXISTING
COVER, STOCKADES, &c.

For time and labour required^ see table, p. 120.

Walls. 54. Brick walls 9 inches thick, if badly built, are liable to be

penetrated through the joints by small-bore bullets, and can
he cut through by short range volleys directed on the same
spot. Practically, however, any fairly well built wall will
give good cover against musketry. Walls alone cannot be
occupied, as a rule, under effective artillery fire, but may,
nevertheless, be utilised for defence, after artillery fire has
ceased.

A wall between 4 feet and 4 feet 6 inches high can be used
as it stands. If a wall is less than I feet high, a small trench
can be sunk on the inside to gain additional cover.

Between 5 feet and 6 feet in height a wall can be notched.
(PI. 11, Fig. 4.)

Above 6 feet in height, a step must be raised inside, to
enable men to either fire over the wall, or through notches, or
else the wall must be loopholed (Fig. 5).
Loop- 55. Loopholes should not be closer together than 3 feet from

holes. centre to centre, and can be made by means of crowbars or
picks. It is desirable to make the opening on the outside as
small as possible, to lessen the chance of the entry of the bullets.
In a moderately thick brick wall the loophole may be commenced
by knocking out a " header " from the outside of the wall,
the interior dimensions of the loophole being afterwards
varied with the direction in which fire is to be delivered,
In actual warfare a rough hole only can generally be formed,

PLat& Jl

HED6E.S
Fi^. 1.

yt^^g^: NcUaraL DztcTv
ire rear

Fzg. Z.

t^ MtturctlliiUh
TTV frortt.

Walls

Fig. 3

0 ston^ coping &.raiJbi7ig
t2v scatter ecb

Fig. 4 ElevatLOTL of Fig. 8

Two Tiers of Fire
7s ^tcLoing ofPlcaiks
anJilBarrels .

SancUbag loaphdU
or caiy other sort
of loophole

«06^h 05

Weller A Graham. L^ Lj.cho Lonuon.

CHAPTER VIII. — IMPROVEMENT OF EXISTING COVER, ETC. 27

which should, nevertheless, conform to the conditions above
laid down as far as possible.

Figs. 6 and 7 suggest methods for preparing walls for a double
tier of fire, which might be used for flanking purposes.

56. In preparing hedges for defence, weak places should be Hedges,
made up with boughs, stakes, wire, &c., and if a ditch is on

the defenders' side, little else requires to be done. If not on
the defenders' side, something in the nature of a shelter trench
may be dug, and the earth thrown up breast high against it
when such command is necessary, and if the hedge is strong
enough to support it.

In no case should excavated earth be thrown in front of the
hedge, so as to indicate its occupation.

The time required to excavate such trenches is longer than
for ordinary trenches on account of the presence of roots,
and the work required to strengthen the hedge.

In preparing a hedge for defence, if the top of the bank on
which it stands is not thick enough to keep out bullets, it
must be made so.

Hedges sometimes form very good screens for field guns.
It would generally be advisable for the guns to be in action
about 150 to 300 yards behind the hedge.

57. Embankments are not as a rule good positions for a Embauk-
firing line, because they offer such a good mark to the enemy's ments.
artillery, but nevertheless embankments in front of a position

and parallel to it, will generally have to be held.

Embankments can be defended by occupying the nearer
edge, as in Fig. 1, PI. 12, or the further edge, as in Fig. 2.

The front edge gives the best command of the ground in
front, but cover can be obtained with less labour at the rear
edge.

58. Either side of a cutting can be defended, according to Cuttings,
circumstances (Fig. 3). The rear side gives the best obstacle ;

the front side is best for a subsequent advance, and secures good
shelter for supports.

A road cut on the side of a hill would generally be visible
to the artillery of the attack for a long distance, and therefore
should not be held unless it offers special facihties for defence.

Fig. 4 shows a method of defending a road, the fence or

28 CHAPTER VIII. — IMPROVEMENT OF EXISTING COVER, ETC

hedge on one side being converted into an obstacle^ and that
on the other used as cover.

Woods.

Woods, 59. Woods vary so much in character that it is impossible

to give general instructions for their defence suitable to all
cases. Those which reach down towards the enemy are very
dangerous and require special consideration.

The two most important attributes of woods, which are
common to nearly all, are the obstacle which they make to
the passage of troops, whether in defence or attack, and the
concealment they offer. As to the obstacle it is the defenders'
business to arrange that it shall cause the least inconvenience
to his own, and the greatest inconvenience to the enemy's
troops. The concealment afforded should be so utihsed as to
be almost entirely in favour of the defence.

The front edge of a wood very often has a boundary capable
of being easily made into a good shelter, while the materials
for abatis are at hand: In order to economise troops, especially
if the edge of the wood is indented, portions may be defended
while the remainder is entangled ; the portions to be defended
being those whence the most fire can be developed. The edge
of a wood, however, often offers a good mark for the enemy's
artillery ; for this reason it is sometimes desirable to place
the firing Hne some distance in advance.

Entrenchments and breastworks in the interior of a wood
involve great labour and should seldom be used. Where the
ground is favourable, clearances in front of interior positions
may be made, and the wood cut down made into abatis.
Log Log breastworks, especially of hard wood, will, of course,

breast- give a good deal of protection against bullets, even if it is not
complete.

If the defence of the rear of the wood is more convenient
than that of the front, the best arrangement will be to entangle
the rear edge and take up a position commanding it and some
distance behind it. The rear edge may be cut so as to leave
well defined saUents. This will induce the attackers to crowd
into these salients and so make a good target.

works.

M^teJZ

Cuttings & Embankments.

Embankments

/ly ;

/t^ 3

5 t.

Railway CuTT'MG.Jkj

;-SS?^-

Road on Hillside

y/el!er& Graham L'"= Litho London

Opposite p(xge 2-S .

PlxxjbeJS

Defence of a House

Doors.

JE^cczt^ door'
Str'utte/d/

Mg.Z.

\'\yctk^ atones

^^f^ff?^^^^^WW?W^^'..

Fi^.S.

^^OjCJ' covers

Ti^.^.

IKeJIer & Graijam. L^ ituho. LondotK.
Opposite pa^e Z^

PUUe Uh

Defence of a House

Doors

JFuj.^.

l^:Z

JPntfrnxxL J^l^^ation

Windows.

Tlsf,3,

JFzff.4^.

of2»^cJcsrL starve^ hetivejgrf.

vVer.er&G'-aham.U? ^Jtho ucndon

CHAPTER VIII.- -IMPROVEMENT OF EXISTING COVER, ETC. 29

Communications through the wood should be improved,
if the front is to be held ; if the position is in the rear of the wood
and the latter is merely to serve as an obstacle, they should
be blocked.

In making clearances, large trees should not be felled.
Much can be clone by judicious thinning.

With limited time, it ivill generally he best to occupy it in
improving the communications rather than in multiplying
obstacles.

Defence of Buildings.

60. Buildings can seldom be held under artillery fire. When Buildings,
time and labour are available they may, however, be prepared

for defence. When screened from artillery fire they are of
great value.

The principles for defence of buildings are the same as those
laid down in Chap. I, Sec. 1, but the following special points
must be dealt with : —

Barricading of doors and ^vindows {see Pis. 13 and 14).
(One door should be available for use and must be
specially dealt with.) Arrangements for ventilation
(usually by upper windows) ; for storing ammunition,
provisions and water ; for a hospital and for latrines ;
and precautions must be taken against fire.
Any neighbouring buildings which are not to be occupied,

should be made useless to the enemy.
If the building is large and strongly built, and it is intended
to make a determined defence, arrange for interior
defence by loophohng partition walls and upper
floors, and providing movable barricades to cover
the retreat from one part of the building to the other.

Stockades.

61. Stockades are improvised defensible walls, which, in Stockades.
addition to affording cover to their defenders, form a fair
obstacle to assault. They are only suitable for defences

of a purely passive character, where not exposed to artillery
fire.

30 CHAPTER VIII. — IMPROVEMENT OF EXISTING COVER, ETC.

The commonest forms of stockade consist of earth, gravel
or broken stones, &c., between two upright revetments
The necessary thickness w^ll be obtained from the table in
Chap. T, Sec. 4 {see PI. 15, Fig. 1).

Eails or iron plates, if available, are useful materials. Types
of stockades of rails and sleepers are shown on PL 15, Figs. 2
and 3.

62. It must be remembered that the loopholes through which
the defenders deliver their fire should be so arranged that the
enemy, if he succeed in closing with the obstacle, will not be
able to use the loopholes in his turn.

Loopholes may be formed of sandbags or by inserting a
plank box in the earth, gravel, &:c., taking care to give some
splay to the rear to admit of lateral range. They should be
from 3 to 5 feet apart.

Loopholes may with advantage be bhnded when not in use
by an old sandbag or piece of sacking in situations where the
nature of the back ground would indicate their position clearly
to the enemy.

If required two tiers of fire can be obtained in a rail stockade
by arranging a staging of sleepers for the upper rank to stand
on, lea^nng sufficient head room underneath the staging for
the lower rank standing on the ground level. In this case
there should be a ditch in front.
Screens. 63. In these da^^s of smokeless powder the value of screens,

both for attack and defence, cannot be over-estimated. Much
can be done in a close country by judicious thinning or leaving
of woods, trees and hedgerows. Where no natural screens
exist they can be made. Smoke sometimes forms valuable
cover for working parties, especially against search hghts.

Sacks filled rather tightly with straw, left open at each end
and slit to allow the escape of the smoke, form simple and
portable smoke producers. They should be lit in the centre
of the straWj so as to burn outwards.

Piafr 15.

Stockades

topu^Ceis dH^€?t^ into qpyjxt/idL/

S'toS'ctpariy

WelU 'KGri^-aip L" urt>o Lordon

Oppoicte page SO,

en AFTER IX. — EARTHWORKS. 31

CHAPTER IX.— EARTHWORKS.

64. Earthworks may be classed generally under two heads, Earth-
viz. : — Trenches and Redoubts. works.

The defences of an extended position will usually be trenches. Trenches.
They may be disposed in irregular lines arranged mainly for
frontal fire, as may be best suited to the ground, or in groups
with intervals. The ground sometimes permits of these
groups being arranged so as to provide flanking fire for the
intervals and front of other groups. In laying out such
trenches the danger of enfilade fire must be considered.

Redoubts will be used principally for isolated positions, Redoubts,
such as posts on lines of communication, or a chain of advanced
posts watching a long line of front. When placed as supports
to the front hne of an extended position they must be care-
fully withdrawn or concealed from view.

With all intrenchments invisibility is of the utmost impor- Inrisi-
tance, and is almost of as much value as the cover itself. bility.

65. Every effort should be made to utihse and improve Existing
existing cover in order to save labour and time. On the ^o^^^'-
defensive there will generally be time to make a trench before

the attack commences. In attacking across open ground,
under fire, men will not, as a rule, be able to stand up and dig. Attack.
When brought to a halt, they will have to make such cover as
they can while lying down, but no opportunity should be lost
of entrenching ground that has been gained.

Siting of Trenches — {See also " Combined Training," 1905,
Section 126).

66. The following points must be considered : — Siting of
A good field of fire ; this is most important and should trenches.

not be sacrificed to any other consideration.

As much concealment as possible, particularly from the
enemy's artillery.

Ground in rear suitable for reserves.

When the position includes commanding ground the
firing hne need not necessarily be on it; it should be

CHAPTER IX. — EARTHWORKS.

Arrangfe-
ment of
trenches.

in the best position for fire effect. It will often be a good
plan to place the firing line at or near the foot of a slope,
so as to obtain a grazing fire, with the artillery on the high
ground above.

The advantage of high ground for a defeusive position is
often over-estimated. It need oidy be high enough to conceal
and shelter the defenders' reserves and their movements, and
to expose the movements of the enemy.

67. The arrangement of trenches should be simple. There
should be one main line of defence. Several tiers of trenches
may sometimes be useful, to increase the volume of defenders'
fire, and also to deceive the attack as to the actual position of
the defence ; but there should be no idea of using these trenches
as successive lines of defence. The defenders should understand
clearly which is the main line of defence, and what it is that
they must hold on to when the assault is pushed home.

The main line should not as a rule be continuous. If
echelonned in suitable lengths, say for companies, or even
smaller units, it will be more difficult for the enemy's
artillery to get the range.

In tracing a trench attention should be paid to probable
enfilade fire.

Every artifice should be used to mislead the enemy as to
the positions of the trenches, e.g., conspicuous dummy trenches
to draw his fire.

Invisibility.

Tnvisi- 68. Every effort should be made to conceal the trench.

biiity. Concealment may be gained by (a) careful siting, i.e.,

position, (h) Assimilation to surrounding ground. When
possible a position should be studied both before and after the
construction of trenches from the front, and especially from
the enemy's artillery positions. Well-marked features of
the ground, such as isolated hedge-rows, Hues of road, sharp
changes of gradient, or anything which casts a shadow are,
at long ranges, more visible than the trenches themselves.

The neighbourhood of such objects forms a target, especially
for artillery fiie, and should when possible be avoided.

PlrrJe JO

Fire Trench es

Surplus ea7*th. m/iy
he hecuped- or sprecLeL
in. re^xr of trerhcJv

*806-S as

we'-e'SiGra^aT' L'' iJtio Lonoon
Opposite pajqie.33.

CHAPTER IX. — EARTHWORKS. 33

The front of the parapet maybe covered with sods or branches,
or whatever will make them look like the surrounding ground.
Sharp hues must be avoided and attention must be paid to
back ground.

If the parapet is on the skyline, spare earth may be piled
up behind the trench to make a back ground for the defenders'
heads. As a rule, however, a sky line is to be avoided.

The parapet should be kept as low as possible consistent
with fire effect ; in some cases no parapet is required.

Trenches.

69 . Trenches are distinguished as "fire trenches" and "cover Trenches,
trenches," according as they are for the firing line or merely

to cover troops not actually engaged.

Fire Trenches.

70. The design of the trench will depend on the time and Fire
labour available, on the soil and on the siting, but the following trendies,
points are important : —

(1) The parapet should be bullet proof at the top; 2 feet

6 inches to 3 feet will iLsually suffice. But see Sec. i.

(2) The trench should be as invisible as possible.

(3) The interior slope should be as steep as possible.

(4) The bottom of the trench (unless there is a step)

should be wide enough to allow men to sit in it.

(5) The interior should be protected, as far as possible,

against oblique and enfilade fire, and sometimes from
reverse fire,
(G) Drainage should be attended to.

71. Types of fire trench are given in Pis. 16 and 17, but see
Sec. .3.

Fig. 1 gives good cover against frontal artillery fire,
and allows room for the supernumerary rank to pass behind
the firing line.

To excavate the normal length of 2 paces of this trench
will take an untrained man about H hours, in moderately
easy ground.

(528'J) c

34 CHAPTER IX. — EARTHWORKS.

In Rpecially difficult soil the width may be reduced to 2 feet.

Should time be available, the cover and the facility of com-
munication may be much improved by deepening and widening
the trench, as shown on PI. 16, Fig. 2.

Should a higher command than 1 foot 6 inches be required,
to enable the defenders to see the ground in front, the parapet
must be heightened with earth obtained from widening and
deepening the trench. A firing step, at least IJ feet wide, is
necessary 4J feet below the top of the parapet, the interior
slope of which must be revetted.

PI. 16, Fig. 3, is a case where the ground in front can be seen
without any command, and it is desired to dispense with a
parapet for the sake of concealment. The excavated earth
must be scattered or removed to form a dummy parapet.

PI. 44 shows how fairly good cover can be rapidly obtained
for men lying down ; the trenches can be connected up £is
shown by the dotted lines.

An elbow rest is & useful feature in a parapet. It increases
cover considerably, gives support to the men while firing,
and is convenient for ammunition. It should be 9 inches below
the crest and 18 inches wide.

Earth thrown up should not le rammed.

Head Cover and Loopholes.

Head 72. Head cover tends to diminish the number of rifles that

cover. p^j-^ i^g p^^ jj^ ii^Q ajj(j reduce the field of view and fire, and

generally makes the work more conspicuous, but is of

undoubted advantage for protection, especially against

shrapnel.

It requires careful arrangement so as to ensure the maxi-
mum of fire effect and of invisibility with the minimum of
exposure.

It will usually be obtained by making notches in the
parapet for the rifle, or by loopholes.
Lo'^p- Loopholes can be made of sandbags, sods, or other materials

hole^. available on the spot, such as biscuit boxes or sacks filled with

R^Ltt J 7

-1

"?3

-I

to
q:

-|W

lli

1,1

—

W€Uftr*6rahani. \J.* Lirtio.London.
Opposile pCLg& J^4.

PZccLe JS.

Head Cover .

SojixL'bcuf Loophjole with. Loophole Plcutes
on Lei^el^ groujvcL.

Ftg. 1 Fig. Z

Section

Fi€f. 3

Sandbag Loophole

Sod

Plan of j*ir Courses

Plan of^&tt Courses

Stbdks to cccrry
tap soTLdba^s

S ECTION

ler&Graham.L" Urho, London
Opprtsitje jtctgfi>3S.

CHAPTER IX.~ EARTHWORKS^ 35

earth. The size of the openings must be governed by the
ground to be covered by fire,* and can best be regulated by
testing with a rifle with the bolt removed to ensure that
neither line of sight nor line of fire are obstructed.

Sandbag loopholes, as shown in PI. 18, Figs. 3 and 4, can be Sandbag
made in a continuous line as close as 3 feet 3 inches from loophole,
centre to centre.

Sandbags sag a good deal unless well supported.

Loopholes made with earth or sandbags may have the larger
opening either inside or outside. If the larger opening be
inside, the loophole is very much less conspicuous, which is
often a point of great importance.

If the larger opening be outside, a defender can fire with much
greater ease, since he can cover the whole arc without moving
his position.

The choice must depend upon the requirements of the place.

A compromise between the two above methods is shown in ,

PI. 19, Fig. 1.

A very good form of loophole which has the advantage of Con-
giving a wide field of view, is a slit all round the work, tinnous
continuous, except for the supports of the material above {see ^^^ ^^ ^'
PL 25).

Loopholes made with hard material, such as stone, must have
the larger opening inside to prevent ricochet.

Steel loophole plates, see Figs. 1 and 2, PI. 18, are articles of Steel
store. They make the best head cover, but cannot, as a rule, loophole
be provided for hasty defence work. plates.

Loopholes should never show against the skyline, but
should be blinded, say, by canvas hung behind them. The
front of the loophole may be masked with branches, long
grass, fee.

Overhead Cover.

73. Overhead cover gives the best protection against
shrapnel from guns and howitzers. It is especially useful

* The minhiium depth of openings for a parapet 2 feet 6 inches tliick
on level ground, using the new service rirte at 2,000 yards range, is, for
the inside, six inches ; for the outside, four inches.

(5289) c 2

3G CHAPTER IX,— EARTHWORKS.

against oblique fire ; 9 to 12 inches of earth, or say 3 inches
of shingle, supported by brushwood or other suitable material,
will suffice. (PI. 20.)

Two sheets of corrugated iron sloping to the rear at about |,
afford good protection against shrapnel {see PL 19.) The
corrugations must be parallel to the line of fire.

Overhead cover of above natures will not keep out a common
shell, but the effect of a burst in the trench can be locahsed
{see below).

A row of heavy steel rails arranged in the same way as the
corrugated iron, has been found to be practically proof against
G-inch howitzer shells filled with high explosive.

Overhead cover against weather may be made with
branches, corrugated iron, canvas, or any other covering
available.

See also Sec. 88.

Traverses.

Traverses. 74. Open trenches and parapets which may be exposed to
enfilade fire and to the oblique fire of artillery, should be
traversed and recessed. Traverses are simple means of
gaining protection against enfilading shell, and also of localis-
ing the effect of a shell bursting in the trench. They are also
effective against rifle bullets, on account of their flat trajectory.
An irregular fine of trench will answer the same purpose, when
it suits the ground.

Against shrapnel bullets coming obliquely, or in enfilade,
traverses will not suffice, on account of the steep angle of
descent of the bullets. Eecesses made in the parapet, lar^e
enough to hold one or two men, give the best protection against
these. See PL 21. Such recesses are best made after the
trench is excavated.

75. Traverses to localise bursts may consist of two walls of
brushwood, with about 1 foot of earth between.

Protected Look-out.

Look-out. 76. In all trenches some sort of protected look-out is useful.
It should not be distinguishable from the front.
A well-made loophole may suffice for this purpose.

Flate. J9.

Fi^.1.

Sod Loophole

J^.2

Elbow ^es\

SocLs

Sods

Overhead Cover

-K / 6

Welter & Graham. L^f Litho London.

PUlIa 20

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Gun Epaulment.

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Fig. 5.

SectUnv across Wix^on Grver.
\ ^ - j^ LenxjftTh aucc^rdiTui toTva/nber*

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Piate 23

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rear crest of hill

COVER FOR ^
WAGONS. ^

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Section on AB

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Section

S/tfe- • r.. we;!ers.r-a-3r

To follon' plate 22.

chaftrr ix.— earthworks. ^ 37

Drainage of Trenches.

77. This is an important point, and should be attended r)rainage.
to from the outset. A gutter should be formed in the trench,
usually at the back, and the bottom of the trench sloped to

it. Any water collecting in it should, where possible, be led off
to lower ground, otherwise into soak pits, which may be about
2 feet or 3 feet in diameter and 3 feet deep.

Communication Trenches.

78. If time admits covered communications should be Communi-
arranfTed behind the firine line. These, while concealing the cation
movements of the defenders, will also permit of the firing line

being withdrawn altogether while the artillery bombardment is
going on. A trench similar to PI. 16, Fig. 4, will usually
suffice.

It may be necessary to make long lines of such approaches,
but every possible use should be made of the ground to mini-
mise labour on them.

They may require parapets on both sides, and where much
exposed may be given overhead cover.

Cover Trenches.

79. Cover trenches {see PI. 24, Fig. 1) are useful to protect the Cover
firing line during a bombardment, and for troops not actually trenches,
engaged.

The section of these trenches may be as in that figure, or,
if more time and material be available, as in Pis. 28 and 29.
When time is limited and materials are not at hand, a section
similar to PI. 16, Fig. 1, might be employed, but with slightly
higher parapet and no elbow rest.

Cover for Artillery.

80. Cover for field guns will take the form of epaulments, or Cover
pits, as shown in Pis. 22 and 23. An ammunition recess must for

be provided close to the gun, and cover for one or more ammu- ^^'"^^^7-
nition wagons near the emplacement is also desirable. There
should be covered communication between the gun emplace-
ment and the wagons. Parapets to be bullet and sphnter

CHAPTER IX.— EARTHWORKS.

proof. The height of the parapet should be regulated by the
site and range. Three feet is suitable for medium and long
ranges. Howitzers will, as a rule, be in concealed positions,
wdierc they can only be reached by high angle fire. If they
are likely to be for some time in one position, e.g., in siege
operations, they can be surrounded by splinter-proof walls
[see Traverses).

Field

redoubts.

Definition.

Kmploj-
ment.

Detached
posts.

Trace.

Field Redoubts.

81. Field redoubts are Avorks entirely enclosed by defensible
parapets. Their dimensions should, as a rule, be such that
they could be constructed in from 12 hours to 24 hours.

It may be generally laid dowm that redoubts in defensive
positions must not, under ordinary conditions, be used on sites
w^here they can be recognised as redoubts by the enemy:
This \\\\\, as a rule, prevent their employment in the front line,
although irregularities of the ground, &c., may shelter certain
portions of this line where redoubts may find place. A redoubt
has greater resisting power against infantry than a group ol
trenches.

As supporting points in rear of the front hne, redoubts w^ill
more often be employed. In such retired positions there will
generally be sites which, while commanding the foreground,
will not be exposed to view from a distance.

It should be remembered that a redoubt does not necessarily
need a high or thick parapet ; a fire trench parapet may suffice.

82. Redoubts may have to be used for detached posts, and
posts in lines of communication. Such works wall often have
to be a refuge, shelter and depot for passing troops, and room
inside must be given. It will hardly be possible to make these
works invisible, as it is essential that the parapets should
conceal the interior from view\ Plenty of splinter-proof cover
should be provided, and a good obstacle near the parapet is
essential.

83. The plan or trace of a redoubt will depend on —

(a) Fire effect required from it.
(6) Configuration of the ground,
(c) Proposed garrison.

Plate Z^.

Cover Trenches
Fig r

REDOUBT(Low Command)

111.

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Opposite pa^e>39

FJjubt 25.

■</eli»rfcGraha(» V* Lirtio. London

To follow plale^ 24

CHAPTER IX.— EARTHWORKS. 39

84. The site should be such that the surrounding foreground Site,
may be well swept by the fire from the parapet, and the work
should be so disposed as to give the strongest possible fire on

the enemy's best lines of attack. There must be no dead angles.

A redoubt may be of any shape that suits the ground and
provides good firing fines. There is no necessity for symmetry
in the design, although it has advantages. On a level site
a rectangle with blunted angles would be suitable.

All faces should be long enough to give an effective fire.
Those making a considerable angle with neighbouring faces,
as in a rectangle, should not be less than 20 yards long, and
the short faces which blunt the angles should be at least
10 yards.

It is often convenient to use curved faces. These, as a rule,
should be struck with a radius of not less than 20 yards.
A complete circle should be avoided, except for very small posts,
as its fire is weak in every direction.

85. The garrison should always consist of one or more Garrison,
units of command. The proportion of defenders, including
supports and local reserves, to size of work should be from

1 to IJ men per yard of parapet, but the proportion of
parapet to men may have to be much larger.

86. In a redoubt in front line exposed to artillery fire Low
invisibihty is the first consideration. This will entail in most command
cases a low command, about the same as that of the neighbour- I'^doubt.
ing fire trenches. This should be combined, w^hen time per-
mits, with a deep trench in rear, both to increase the cover

and to afford cover to troops not actually engaged. A redoubt
of this type is shown on Pis. 24 and 25.

87. For a work placed as a supporting point behind the High
front line, the question of invisibility is not generally so urgent, command
In this case a high command has four advantages : —

(1) It has a better command of its field of fire than a low

redoubt.

(2) It has a better moral effect on its defenders.

(3) It conceals the whole of the interior of the redoubt

from view.

(4) It can be easily combined with a good obstacle.

CHAPTER IX. — EARTHWORKS.

Reverse
fire.

Overhead
cover.

The disadvantages lie in the extra labour and time entailed
in making the large parapet.

In the case of a detached post, which may be surrounded,
invisibility is of much less importance than that the defenders
should be able to move freely about the whole interior of the
work without being seen.

A type of parapet with high command is shown in PL 26.

Since a redoubt is intended for all round defence, precautions
must be taken to prevent the defenders suffering from reverse
fire.

88. Overhead cover for a redoubt should consist of about
9 to 12 inches of earth supported on brushwood or other
material.

Various forms of these shelters are shown on Pis, 26, 27, 28,
and 29. They all require a great deal of material. They
should always be given transverse partitions, at intervals of
from 10 feet to 12 feet, to localise the effect of sheU.

A fairly bomb-proof roof can be made with rails sloping
down from line of fire [see Chap, IX, p. 36).

Shelters for the flanks, when artillery attack is expected
from the front only, may be given in trenches roughly parallel
to the front faces ; some of these may be continued with ad-
vantage across the whole redoubt, for purposes of com-
munication.

When the artillery attack may come from any direction,
as with some detached posts, the shelters must be arranged to
meet this by facing various directions.
Entrances. 89. The entrance to a redoubt used in civilised war may be
a gap left in the face least exposed to attack, and covered
by a traverse, inside or out as may be most convenient. The
entrance should be wide enough to admit a wagon, see
Chap. XXII.

90. The drainage of the redoubt and trenches must always
be provided for, and should be put in hand as soon as the work
is commenced. Soak pits will seldom suffice for this purpose,
and, as a rule, the drains should be led out of the redoubt
to lower ground if possible.

91. When a redoubt is to be occupied for more than a few
hours, latrines and cooking-places should be provided within
it.

Drainage.

Latrines,
&c.

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CHAPTER X. — OBSTACLES. 41

92. Obstacles should always be provided in connection Obstacles,
with redoubts. They must not mark the j^osition of the
redoubts.

The nearer the obstacle is to the parapet the less labour
and material will be required, and the more efiective will be
the defence, especially at night.

CHAPTER X.— OBSTACLES.
For time, labour, tools aiid material required, see table, p. 120.

93. Obstacles judiciously placed add very much to the strength General
of a defensive position, and are especially useful as a protection eonditious
against night attacks. The following conditions should be
observed : —

(a) They should be under the close rifle fire of the defender.

For small posts or redoubts they should be quite close,
so that they may be effectively defended at night.
They should afford the enemy no cover, and, if
possible, be sheltered from his artillery fire.

(b) They should be difficult to remove or surmount, and

will be most effective if special appliances, not usually
carried by troops, are required for their removal.

position may be unknown to the attacking force.

(d) Except where the purely defensive is inevitable, they

should be arranged so as not to impede counter
attacks.

(e) As obstacles on a large scale may interfere with an Caution.

advance, they should not be constructed without
authority.

For the protection of small posts at night some sort of
automatic alarm is desirable, such as tins hung on a wire,
rifles fired by trip wire, &c., see p. 47.

42 CHAPTER X. — OBSTACLES.

abatis. 94. Abatis formed of limbs of trees firmly picketed down and

interlaced, with the branches turned towards the enemy
and pointed, form a very efficient obstacle (PI. 30).

Figs. 1 and 2 show method of covering abatis from artillery
fire.

Fig. 3. — The method of forming an abatis from small
branches. Several rows are used, the excavated earth being
replaced after the branches are secured. To make abatis
carefully, at least a relief of six hours and a strong working party
are required, so that very little of it can be undertaken in
hastily-fortified positions. A very effective abatis may, how-
ever, be made much more rapidly when the trees can be
utilised where they are felled, no excavation being made for
them and the branches being only roughly trimmed.

Strands of wire interlaced between the branches are a useful
adjunct to abatis.
Tree 95. Tree entanglements (Fig. 4, PI. 30) are formed by cutting

entangle- trees, brushwood, &c., nearly through at a height of about
3 feet, and interlacing or securing the branches by pickets
to the ground. They make a formidable obstacle at the edges
of woods and orchards, and for blocking roads, and can often
be formed w^hilst clearing the foreground.

Wire 96. A low wire entanglement is formed by stout stakes

entangle- (Jnyen into the ground about 6 feet apart, in rows arranged

Low ^' chequerwise, their heads being connected by strong w^ires

twisted round them and crossing diagonally about 1 foot or

18 inches above the ground (Fig. 3, PL 31).

The outside pickets should have ware stays, as shown in
Fig. 3.

It is not a good obstacle unless constructed amongst brush-
wood, small bushes, or long grass, which conceal it, when it
may be of great use against mounted troops. It is especially
effective in the bed of a river.

High. 97. High wire entanglements form effective obstacles, es-

pecially if barbed wire be used. PI. 31, Figs. 1 and 4, give
two different types. Fig. 4 shows a method of improving a
wire fence, but is not so efficient an obstacle as that shown in

ments.

I^lcutG 30.

Obstacles

Abatis.

j^ 1

Palisades

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High wire Entanqlement

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Barbed wires

WcJIcr 4 Graham. L**^ UthoLondon.
Opposite poLge ^3.

CHAPTER X. — OBSTACLES. 43

Fig. 1. The pickets should be about 4 or 5 feet high, driven
firmly into the ground and sta3^ed as in the low wire
entanglement.

Where two wires cross they should be fastened together with
fine wire or string. Where materials are available the obstacle
should be two or three rows deep.

98. Palisades are occasionally used for the defence of ditches, Palisades,
and for closing the rear or gorges of partially enclosed works.

They would principally be employed in savage warfare. They
are made of timbers about 10 feet long, arranged so as to form
a stout open paling, and pointed or spiked at the top. The
timbers may be round, spUt, or sawn to a rectangular or tri-
angular section ; they should be 6 inches to 8 inches wide,
and are placed upright about 4 inches apart, and spiked
to two ribands about 1 foot from either end, the butt ends
being sunk 3 feet or 4 feet into the ground. The top riband
should be on the defenders' side of the palisade. They are
most conveniently made and placed in lengths of 10 feet or
12 feet, the ribands being arranged so as to overlap.
(PI. 30, Fig. 5.)

99. Fraises are palisades placed horizontally, or nearly so. Fraises.
They should point downwards if placed on the defenders'

side of the ditch and upwards if on the enemy's side. Both
ribands are buried, the one nearest the points being placed
underneath, the other on top. The points should, if possible,
be at least 7 feet above the bottom of a ditch.

100. Barricades, used to close streets, roads and bridges, Barri-
can be made of any materials at hand. They should not, as a cades,
rule, completely close the road to traffic, but be made in two
overlapping portions, or be placed where a house standing
back from the general line of building allows a passage round

the barricade.

The defenders should be able to fire over them, and, if
placed in a street, they should be flanked both in front and
rear by the fire from adjacent houses.

101. Foagasses and land mines {see "Instruction in Military Foujjas'es
Engineering," Part I) are a useful adjunct to the defence. ^"^ ^*"*1
They should only be laid by officers who have a thorough ^^^°^^'
knowledge of explosives.

CHAPTER XI. — DEFENCE OF POSTS, VILLAGES, ETC.

Inunda-
tions.

Passage of
obstacles.

Illumina-
tion of
obstacles.

General.

Choice of
ground.

102. Inundations can be made by damming up a stream.
A bridge is a good place to select for the purpose.

If the inundation is likely to be very shallow, the ground
should be first prepared by digging irregular trenches and holes,
the existence of which will render the passage of even a shallow
inundation a difficult matter.

103. Obstacles may be crossed by using hurdles, planks,
fascines, bundles of straw, &c., or by rough ladders with steps
made of pieces of plank about 9 inches wide and a pace apart.
Handsaws, axes, bill-hooks and cutting pliers should always
be carried by a party removing obstacles. Ropes, grapnels,
hedgers' gloves and guncotton may also be useful.

104. For illumination of obstacles see page 47.

CHAPTER XI.— DEFENCE OF POSTS AND VILLAGES.

Organisation for Defence of Large Positions.

{See also " Combined Training," 1905, Section 123 and
following Sections.)

105. Campaigns of the present time often entail a long
line of communications in a more or less hostile country.
Even when protected by a field army this is, if the enemy is
strong in mounted troops, very liable to raids and must there-
fore be protected by fortified posts. These posts may involve
(a) the protection of a comparatively large area of ground or of
villages containing supply depots, and will, in the case of a road,
have to afford protection to the convoys and transport animals
which are working along it, or, if on a railway, to protect
rolling stock, station buildings, telegraph stations, &c. ; or
(6) may only have to protect a very hmited area, e.g., bridges,
signalUng stations.

106. For strategic or other reasons the choice of ground
for a post may be limited. Tactically the ground to be
defended will not always be of the best, and the art of the
field engineer will be taxed to the utmost. Water may not
be readily obtainable, and may have to be stored ; to insure
that this and all other supplies are easily accessible, much
forethought is required.

CHAPTER XI. — DEFENCE OF POSTS AND VILLAGES. 45

107. Every man employed on communications is in a sense Scheme of
wasted, therefore the garrisons of such posts must be kept as i^ptV-nce,
low as possible, and every effort made by the skilful use of g^'"'^**^°^'
ground and field fortifications to economise men.

The main princij^les to bear in mind are as follows : —
{a) Organisation of defence.

(b) Defenders to be close to the ground they have to defend.

obstacles (automatic alarms if possible).
{d) Clear field of fire, adequate cover, good communica-
tions, including telephones, telegraphs, or a well
organised system of signalUng.

Plenty of time is usually available for the organisation
of the defence, and in these days of rapid fire, given adequate
supplies of ammunition, food, water and material, small posts
can be made practically impregnable against raid attacks,
even though the invaders be accompanied by a few guns ;
while larger posts can be so held that, even should the enemy
be able to penetrate under cover of darkness, the risk and
loss involved would be hardly worth the attempt.

Owing to the paucity of troops the defence will usually
be entirely passive, and except for a small reserve to meet
emergencies, every man will have his post assigned to him,
and every rifle will be in the first hne. Works and picquets
suddenly attacked at night cannot, as a rule, be reinforced from
a distance, and for this reason it is essential that the garrisons
told off for the defence of such works should live quite close to
them.

108. The defence of a post of class (a) (Sec. 105) will consist Detail,
of a ring of closed works supporting each other ; the number and
distance from the centre will depend on the ground and troops
available ; the intervals will be closed by a strong obstacle,
which latter must be flanked by a fire from the works. The
works themselves, in view of a night attack, must be sur-
rounded by an efficient obstacle at a very close range, say
20 to 50 yards. The field of fire must, of course, be cleared as
much as possible. In most cases an inner hne of defences
will also be required, and possibly a " keep.'*

4G CHAPTER XI.— IJEFENCE OF POSTS, VILLAGES, ETC.

Tiiis ring of defences will not be of as elaborate a pattern
as those of the outer line, described in the paragraph following,
and will generally consist of fortified houses, garden enclosures,
small blockhouses, &c., placed in the immediate outskirts
of the village or depot, and arranged so as to sweep all approaches
and internal communications.

The posts of class (6) will consist of only one or two of the
above works, and their garrisons may vary from say 6 to 50
men.
Type of 109. The types of works will necessarily depend on the nature

work. Qf ^]^Q probable attack. If the enemy is provided with artillery

deep trenches and splinter proof cover must be provided
(unless the ground affords adequate cover close at hand) ;
against rifles only, walls or blockhouses may suffice. Against
badly armed savages stockaded enclosures are good enough.

Invisibility is not essential, but every effort must be taken,
with due regard to effective rifle fire, to protect the defenders.
To this end head cover is necessary, and overhead cover often
desirable, while, since the attack is hkely to come from every
direction, enfilade and reverse fire must be considered. Each
of these closed works must be self-contained, the storage of
reserve ammunition and water is imperative.
Design HQ. The construction of the works will mainly depend on

construe- ^^le materials locally available. South Africa produced corru-
uorks. gated iron and shingle blockhouses surrounded by barbed
wire ; on the north-west frontier of India stone sangars are
the rule ; in the Lushai Expedition of 1889 bamboo stockades
were made ; in the Soudan breastworks of sand and thorn
zerebas. Where railway stations have to be protected,
blockhouses, stockades and splinter proofs made of rails and
loopholed buildings will predominate, while for a bridge the
piers and girders can often, with a little ingenuity, be made
into good cover for a small post.

In savage warfare the best hints as to designs may generally
be got from the enemy, who, in the course of intertribal warfare,
will most likely have evolved the types of defence best suited
for local materials, and to resist the same form of attack and
weapons which he will employ against us. Such types, when
improved by the light of our own knowledge, modified to

£iiZ££z

Defence of a Post on a line of Communications .

{Springfontein —South African iVar/899-OZ .)

1 nil

FORU®

i^^UCvmphmaitfafftflea

TUjcLc 33

Defensible Post
UcHA Jawa 1897.

To follow plate 32>.

I'LuU 34.

Defensible

POST.

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Fig, 2^.

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Profile of Stockade

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around.

WederiGraham. 'J* LiHiotondon

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LusHAi 1889.

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CHAPTER XI. — DEFENCE OF POSTS, VILLAGES, ETC. 47

suit our weapons, and executed with the aid of good tools
and engineering skill, will, as a rule, be suitable for our own
use. For types of such defence, see Pis. 32 to 41.

111. Automatic alarms and flare lights, worked mechanically Alarms
or by electricity, are useful where night attacks may be ex- *^^ flares,
pected. They are usually combined with obstacles. One

of the simplest alarms is a row of tin pots, each containing a
pebble, hung on a wire fence so as to rattle when the latter
is disturbed. A piece of tin, 2 inches to 3 inches in diameter,
e.g., the top of a tin pot, bent round the wires answers the
same purpose. Trip wires can be arranged to fire a rifle or to
fire a cartridge, which in its turn will ignite a flare {see PI. 43).

For electric alarms, see Part 1, 1.M.E.

Arrangements for automatic alarm signals in connection
with entanglements or intermediate fences, generally have to
be improvised on the spot with whatever material is available.

112. The spring gun shown in sketch (PI. 37) is simple to fix Meclmni-
and is reliable in its action ; another mechanical device is cal alarms,
shown in PI. 43.

113. Means of temporarily illuminating the foreground will lHumiua-
suggest themselves according to the material available. The ^^^" ^^
illumination must be arranged so as to leave the defenders in ground,
shadow.

A "flare " made of tow and oil is described on PL 43. A
special illuminant is made in the Ordnance Factories under
the name of " Lights, illuminating, wreck." This can be lit
with a match or with either instantaneous, or safety fuze.
The instantaneous fuze should be stripped to ensure good
contact. The light will illuminate a circle up to about 100 yards
diameter and will burn for 20 minutes.

114. On a dark night it is difficult to ensure the men's rifles Fixed rifle
being aimed in the required direction. Any device to assist i*«st.
them in this matter is useful. In the South African war of
1899-1902 " fixed rifle rests " were employed to fire along

the obstacle. By the arrangement shown in PI. 42, a number
of rifles can be clamped in the required direction and elevation,
while only one man, who can be practically under cover,
is required to load them; failing this, some such device as a
wooden bar can be arranged across the loopholes, to prevent

48 CHAPTER XL— DEFENCE OF POSTS, VILLAGES, ETC.

a man raising his rifle barrel too high. Posts painted white
on the defenders' side make a good aiming mark, if the night is
not too dark.
Steel loop- 115. Loopholes made of sandbags, sods, &c., unless very-
holes, carefully made, do not afford a good field of view and fire
combined with adequate protection. To meet this objection
a steel loophole plate has been introduced into the service. It
would be specially useful for det?vched posts. {See PI. 18,
Fips. 1 and 2.)
Entrances. H g. The entrances to closed works must be carefully attended
to. They may be closed by a gate, barbed wire or other
obstacle. When wire is used, a good plan is to construct an
intricate winding approach, making access by night difficult.
In all cases entrances must be covered by the fire of the defence.
Entrances to admit artillery require a width of 7 feet.

Defence of Villages.
Tillages. 117, Villages will very often occur in or near a defensive
position, and although they are unsatisfactory for defence they
must generally be occupied, rather than be left to the enemy.
They conceal the disposition and strength of their garrisons,
and afford a shelter from the weather, but they take up a large
number of men who are necessarily scattered.

A village should be divided up into well defined sections,
each held by a tactical unit. Each section might have two
lines of defence. There will be a general reserve for the
whole under the commander of the village, to reinforce a hard
pressed section, make local counter attacks, and furnish the
garrison of the central keep of the village, if any.

1 18. The arrangements of the defence might therefore be as
follows : —

(1) Clearing field of fire.

(2) Making communications.

(3) Providing or improving cover for first line along

hedges, garden walls, &c., loopholing walls of houses
as a second line.

(4) Placing obstacles. This would be partly done at

the same time as (1).
i(5) Preparing keeps.

Plcite ^74.

Cove^ for* Oiztposte

Fia 3

Trvo/er^G Cfyvermg entrccnco
flpow^ exposed iScceJ

COVER - LYING DOWN

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^^w v^;# %^<?'s

.#1^

hf^p;,;,^ >?i^

CHAPTER XI. — DEFENCE OF POSTS, VILLAGES, ETC. 49

Defence of Camps.

119. When operating against an enemy who is accustomed Camps.
to make night attacks, the defence of camps is a most important
question. There are two essentials for camp defence : the
first is a well defined firing hne for the defenders, and the second
is a good obstacle in connection with it.

For a small force the first thing to be done on arrival in
camp is to mark out the positions to be taken up in order to repel
a night attack. If there is only time to do this with a line of
stones, it will give the defenders a definite line of defence and
something to hold on to.

For convenience in camping, troops should generally occupy
the same relative positions each night, but this convenience
must be sacrificed to the arrangements necessary for defence,
as it is very important that units should camp close to the
ground which they would have to hold in case of attack.

In selecting a camp regard must, of course, be had to the
position of the water supply. This should always be under
effective rifle fire, but it must be remembered that a good
position against probable night attacks is one of the first
considerations.

Cover for Outposts.

120. Where no natural cover exists, outposts should be Outposts
entrenched.

The guiding principles in the design of the defences should
be : —

The provision of an all-round field of fire and the protection
of the garrison from reverse fire.

Plate 44, shows various types of cover suitable for out-
posts. Such works should, whenever possible, be surrounded
with obstacles.'

■ (5289) P

50 CHAPTER XI. — DEFENCE OP POSTS, VILLAGES, ETC.

Organisation for Defence of Large Positions.

Defensive 121. In order to ensure a good system of command and
positions. orp;anisation, defensive positions should be divided into well-
defined sections, each under a separate commander, to whom
should be allotted a distinct force, e.g., a division, brigade,
etc. {see " Combined Training ").

Each section commander will be responsible for the
occupation and preparation for defence of his section in
accordance with the orders received. He will either indent
on the service or department concerned, or may make
arrangements by hire, contract, or requisition with the local
civil authorities, according to the circumstances of the case,
for such extra labour, tools or materials, as may be required.
For Tables, giving roughly time required for various works
and form for working parties, which will be found useful in
connection with the above, see pp. 120 and 136a.

CHAPTER XIL— TEMPORARY ROADS.

1 22. Temporary communications by road are usually Tem-

required :— " vovnvy

(a) In comiection with a defensive position to enable '-■°°^™^'^^"
^ ' , -,.■, -IP • cations,

troops to be readily moved irom one portion to

another.

{b) For the movement across country of detached

columns.

In both cases provision will generally have to be made for
wheeled vehicles, while simple means to enable the infantry to
pass dryshod over water should not be neglected. The pro-
vision or improvement of such communications can, as a rule,
be carried out bv unskilled labour. For more permanent work
see Chap. XXII, Part II.

Communications inside a position will consist in repairing
existing roads. filUng up soft places, cutting ramps in steep
ground, cutting gaps through fences and clearing roads or
paths through woods.

The points to be kept in mind are : That troops should be
able to move on as broad a front as possible, and that troops
and messengers should be guided to their destination by sign-
posts, by " blazing " trees or other means.

The work in connection with detached columns will generally
consist in repairing existing tracks or fords and making boggy
or soft ground fit for wheeled transport.

Since soft ground, even though passable, is very trying to
draft animals and causes delay, a little labour, well applied, will
be amply repaid.

123. The best foundation for a temporary road over boggy Tem-
ground is a layer or layers of fascines placed touching one porary
another ; the top row must he across the direction of the ^'^''^^^ o^^'^'
traffic, but when time is not available or suitable material not gpf^nd
at hand, much can be done by throwing down brushwood,
heather, or even straw or grass, care being taken that this,

like the fascines, is laid across the road.

If there is much wheeled transport, a reserve of material
should be collected to replace any that gets worn through.
(5289) D 2

52 CHAPTER Xlir. — KNOTTING AND LASHINGS.

In very wet ground it may be necessary to dig a drain on
each side of the road {see PL 82, Fig. 3).
Corduroy 124. Where timber is available and heavy traffic is expected,
road. a " corduroy " road may be made. This is constructed by

felling trees, cutting them to the required lengths and laying
them across the road at right angles to its direction, ribands
being spiked to them at either end ; or the logs may be held
together by interlacing with rope or wire.

The interstices between fascines, brushwood, logs, &c., may
be fUled with small stones and earth to make a better surface.

CHAPTER XIII.— KNOTTING AND LASHINGS.

Knots and 125. The following are the most useful knots for bridging
bitches. and lashing spars, and their principal uses : —

(a) To make a knot on a rope, or to prevent the end from

unf raying, or to prevent its sUpping through a block ;

the thumb knot (Fig. 1, PL 45) or the fgure of 8

(Fig. 2).
{h) To hend or join two ropes together. The reef knot

(Fig. 3) for dry ropes of the same size ; the single

sheet hend (Fig. 4) for dr\^ ropes of different sizes ;

the double sheet bend (Fig. .5) for great security or

for wet ropes of different sizes, and the hawser hend

(Fig. 6) for joining large cables.

The bowline (Figs. 7 and 8) for a loop at the end of a
rope, the bowline on a bigh^ (Fig. 9) for a loop in the
middle, with a double of the rope.

[d) To secure the ends of ropes to spars, pickets, &c., or to

other ropes.
Half hitch (Fig. 4, PL 46) for securing the loose ends

of lashiDgs, &c.
Clove hitch (Figs. 1 and 2, PL 46) (two half hitches)

generally used for the commencement and finish of

lashings.

:FZjcct^ 4-5.

KNOTS

:Fiy.5.

SeiscLrzg

J^.9.

J^oWlznje^

5186% OB

W<ll«r i Graham. L^o Litho.Undon.
OppcsiXs ptxgfe^S^

Plat^46.

KNOTS.

ZMaZfJIibch^

J^i^.^.

Z^cd/'JBztoh^es.

JBervdy

JY^.S.

JF^.^.

(Umzrrfjenc/eciy

619 f 8.99.

Weller & Graham, L^ LithaUsiion.

.I^Jt^ 4/7.

KNOTS

SFr-^.

CoctkjPa4y,(m/

corrurvenjeedy

StopptfT

JVy.S.A

Jjsn^torL^

Shirwr/210 ou Gash/

sise.8. 9S,

#eHer*Oraham.-L!- Litlw. Lontfoiv
To fbULow platje 4-G .

CHAPTER XIII. — KNOTTING AND LASHINGS. 53

Timher hitch (Fig. 3) for catching hold of timber, &c.,

where the weight ^vill keep the hitch taut.
Round turn and two half hitches [or rolling bend) (Fig. 5)
for belaying (or making fast) a rope so that the strain
on the rope shall not jamb the hitches.
This will be used for making fast a rope to a bollard
or anchorage. Should the running end be incon-
veniently long, a bight of it should be used to form
the half hitches.
Fishermen's bend (Fig. 6), for making fast when there
is a give-and-take motion, e.g., for bending a cable to
an anchor,
(e) To fix a spar or stick across a rope.

Lever hitch (Fig. 7), for drawing pickets by a lever and
fulcrum, fixing the rounds of a rope ladder, fixing
bars to dragropes, &c. v

(/) For forming a loop on dragropes.

Man's harness hitch (Figs. 7 and 8), the loop being of a
size to pass over a man's shoulder.
{g) To fix a rope with a weight on it rapidly to a block.
Catspaw at the end (Figs. 1 and 2, PL 47) or in the

middle of a rope (Fig. 3), for hooking on a block.
Blachvall hitch (Fig. 5), a simple hitch (with a pliant
rope) which will only hold as long as the weight i^'
applied.
(h) To transfer the strain on one rope to another.

Stopper hitch (Fig. 4), for use on occasions when it is
necessary to shift the strain off a rope temporarily.

126. To sling a cask horizontally. Make a long bight with a siingmg
bowline and apply as shown in Fig. 6. casks.

To sling a cask vertically (Fig. 7). Place the cask in a bight
at the end of the rope, and with the running end make a
thumb knot round the standing part of the rope. Open out
the thumb knot and slip it down the sides of the cask. Secure
with a bowline.

127. A rack lashing, an article of store, consists of a length Rack
of 1 J-inch rope, with a pointed stick at one end. Used for lathing,
fastening down ribands at the edge of the roadway of bridges.

CHAPTER XIII. — KNOTTING AND LASHINGS.

BclaTing.

Commenced with a thumb knot at a, Fig. 1, PI. 48, the end
t\visted in the bight. The stick is then put into the bight,
t^^^sted against the hands of the clock till all is taut, and
finalh^ jammed in from right to left between the lashing and
the outside of the riband. A rack lashing is readily impro-
vised (Figs. 1 and 2, PI. 48).

128. To belay a cable to belaying cleats. First take a round
turn \\ath the standing part of the cable on the belaying cleats,
then as many figure of 8 turns as necessary. Half hitches are
on no account to be used in belaying any rope which is likely
to have to be cast off quickly.

Square or

transom

lashing.

Dingonal
liisbing.

Lasliing
block.

Lashings.

129. To lash one spar square across another, commence by a
clove hitch on spar a below h, PI. 48, and twist ends together,
carry at least four times round the spars, as shown in figure,
keeping outside previous turns on one spar and inside on the
other ; two or more frapping or cross turns are then taken, the
corners of the lashings being well " beaten in " during the
process, and finished off with two half hitches round the most
convenient spar (Figs. 3 and 4, PI. 48).

When the spars are the leg and transom of a trestle or frame,
the clove hitches should be on the leg below the transom,
and the lashings should be finished off on the transom outside
the leg.

130. To lash two spars together that tend to spring apart.
Begin with a timber hitch or running bowline round both
spars and draw them together, then take three or four turns
across each fork and finish with frapping turns and two half
hitches. (Fig. 5).

Wedges with well rounded points are often useful for tighten-
ing lashings. They are generally used by builders in scaffolding,
and should be driven in at the top of the lashings.

131. To lash a block to a spar. — The back of the hook is laid
against the spar, a clove hitch is taken round the spar above
the hook, then several turns round the hook and spar, and
finished off with two half hitches round the spar below the
hook (Fig. 6).

LASHINGS

r/aia.48.

JFz^.^

Jtct/*k/ JOcLshinjq

TUf.S.

Tig. 4-.

:Fiff.5

IWUZB

JFu/.7. So7^fciSty

VVeMe;- J Graham L^<? Jtho. London.

To fctcepaffe . ^4

CHAPTER XIV. — BBIDGES. 55

132. The hook of a block is moused by taking some turns Mousing
round it with spun yarn or very light lashing, commencing ^ block,
with a clove hitch on the back of the hook and finishing off

with one or two frapping turns and a reef knot (Fig. 2, PI. 47).

133. The end of a rope is seized to the standing part with spun Seizing,
yarn or string, by forming a clove hitch round one of the ropes

with the spun yarn near its centre, taking each part round both
ropes in opposite directions, leaving one end long enough to
take two frapping turns between the ropes, and connecting
the two ends with a reef knot (Fig. 6, PI. 45).

134. A picket used as a holdfast must be driven into the Holdfasts
ground at a slope to meet the strain. If the latter is great o^ anchor-
and the pickets small, additional strength is gained by the ^^^^'
methods shown in Figs. 7 and 8, PI. 48. In using heavy rope, three

or more pickets can be driven in a cluster to form a bollard.
If a large piece of timber is used as a bollard, its corners must
be rounded off. Fig. 9, PI. 48, shows a method of using a log
for large strains.

135. For strength of rope, wire and lashings, see Part II.

CHAPTER XIV.— MILITARY BRIDGES.

136. The approximate site for a bridge will usually be decided ^i^'«-
by the tactical requirements in selecting the exact position
over a river, and regard must be had to the following points,
most of which must also be considered when an existing bridge
has to be repaired, viz. : The nature of the banks and ap-
proaches, the nature of the bed, width to be bridged, depth of
water, strength of current, and the probability and extent of
floods. If a tidal river, the rise and fall of the tide should be
ascertained. A note should be made of any material near the
proposed site which would help in the construction of the
bridge.

137. The approaches on both sides of a bridge are of the utmost Banks
importance, marshy banks should be avoided, if ramps are ^^^
required the gradients should be easy. Moaches.

56 CHAPTEPw XIV. — BRIDGES.

Easy access and a difficult exit is sure to cause a crowding
on the bridge.
Strength 138. The simplest plan for measuring the velocity of a strea m
of current, is to use a light rod weighted at one end so as to float nearly
vertically, with its tip above water. Note the distance it
floats in a given number of seconds ; then seven-tenths the
mean number of feet a second gives the number of miles an
hour, in which terms the velocity should be stated.
Materials. 139. The materials usually available in the field are timber of
all sorts and sizes, railway plant, hemp or mre rope and floating
material.

The different parts can be fastened together with rope or
wire, iron bolts and nuts, spikes and dogs, iron straps, &c.

The simplest construction consists of round spars lashed
together with rope or wire, but squared timbers, e.g., timber as
used in the construction of houses, and iron fastenings, are often
more easily obtained than spars and rope. Iron fastenings,
however, necessitate a few carpenter's tools.
Form of \^Q, The form of bridge will vary according to the materials
^ ■ available, the traffic expected and the nature, breadth, depth,
&c., of the span to be bridged.

When bottom can be touched throughout, a trestle bridge
(PI. 49, Fig. 1), or some form akin to it, will generally be the
moot economijal in material and the easiest to make. The
method of constructing it should be thoroughly understood.
When there is no available bottom the bridge becomes more
complicated: Sinlple bridges for small spans are the single
lock bridge, the double lock bridge, and the cantilever bridge
(numbers used in the North of India). These are described in
Part II. Where floating material is available and depth of
water and current are suitable, a floating bridge will be the
quickest and simplest to make. For long spans where bottom
cannot be touched, tension or suspension bridges, or
some form of girder bridge, may be suitable, but their
construction requires skilled labour and will not be dealt with
here.

Fig. 3 shows a combination of frame and trestle. Fig. 4
of floating piers and trestle — the depth of the gap in each
case necessitating some support other than trestle.

I'lcct^AU

TYPES O? BRIDGES.

Tia. 7.

'-"-^

jn^.s

Sf-iff.^-.

0/ipcs4jC^ ,f>-',£^ SB

P/^.//? oO

s,3e.6. OS.

BRIDGES

Fu/.^.

Weiler&Gradam. L!r' Lirho.London
OpposLte pouje 51.

CHAPTER XIV. — BRIDGES. 57

141. The same nature of roadway can be applied to cacli Construc-
type of bridge, and its usual form is shown in PL 50, Fig. 1. ^'^^^ ^^

The planks or chesses, A, A, placed across the width of ^^^^ ^*^'
roadway are supported on longitudinal baulks or road-bearers,
B, B, which in their turn rest on transverse transoms, T, T, and
the method of supporting these last depends on the type of
bridge. The chesses are kept steady by two ribands, R, R,
which are secured to the outside baulks either by rack lashings
or by lacing, or the chesses may be simply nailed down.

142. A width of 8 feet in the clear — ^.e., the clear space between Width of
the ribands — suffices for infantry in fours, for military vehicles in roadway.
one direction, and for c&Yalvj in. half -sections — i.e., two abreast;

but 9 feet in the clear is a better width, especially when there is
likely to be a sway on the roadway, as frequently happens in
the case of floating and suspension bridges.

The " normal " width of bridge is 9 feet in the clear.

Six feet will take infantry in file, cavalry in single file, and
field guns passed over by hand ; IJ feet to 3 feet will take
infantry in single file.

143. Planks IJ inches to 2 inches thick are sufficient for Chesses.
ordinary traffic.

For continuous or heavy wheeled traffic additional chesses
should be laid longitudinally, to form wheel tracks.

Chesses can be economised, if they are longer than the width
of the bridge, by placing them diagonally.

Hurdles, short fascines, corrugated iron, &c., can be used
in lieu of planks, but are not good for horse traffic.

When material is available, chesses may be laid on the ground
on the banks on each side for a short distance, to allow horses
to become accustomed to the noise before actually getting
on to the bridge.

1 4 4. A handrail should be provided, especially for horse traffic. Handrail
They must be strongly built. Screens on either side are desirable and
for passing animals over a bridge, especially over running water, ^^^eens.

145. In most bridges the ribands should be fairly pliant, in Ribands,
order that the rack lashings may press them tightly down on
the chesses throughout. In suspension and floating bridges,
however, stiff ribands are desirable, as they tend to stiffen
the bridge.

58 CHAPTER XIV.^-BRIDGES.

Rack lashings should be applied at intervals of 4 feet or
5 feet.
Baulks. 146. The number of baulks depends upon the size of the

timber available. They should be sufficiently close together
to support the chesses.
Bays. 147. The distance bridged by one set of baulks, i.e., the

distance between any two transoms, is called a hay.

The length of bays depends chiefly upon the size of available
baulks ; 10 feet to 15 feet is a convenient length.

When the trestles are large, material and labour should
be economised by making the bay as wide as the length
and strength of the available road-bearers will allow.
Strength 148. Whatever arm of the service it is constructed to carry,
of bridges. ^ bridge should be capable of supporting it when crowded
in the formation for which it is intended. Thus a bridge
intended to carry infantry in fours should be strong enough to
take infantr}^ in fours when crowded.

A bridge that will carry infantry in fours crowded at
a check wiU carry field guns and 5 -inch howitzers and most of
the ordinary wagons that accompany an army in the field.

Timbers of bridges for carrying heavier weights, e.g., guns
of position, should be calculated {see Part II.).

The following approximate dimensions for spars of unsdected
timber are necessary for carrying infantry in fours crowded : —
For bays of 15 feet — Road - bearing transoms, mean
diameter, 10 inches. Baulks (six), mean diameter,
7 inches.
For bays of 12 feet — 1 inch less than above will suffice.
Other timbers not affected by length of bay : —
Ledgers and handrails, mean diameter, 4 inches to 6 inches.
Braces and ribands, 3 inches at tip.
Legs, trestle, mean diameter, 6 inches.
These dimensions are calculated for spars of rather weak
wood, such as larch, and allow for a factor of safety of three.
Five road-bearers are enough for selected spars.
Camber. 149. The roadway is generally constructed with a sHght rise
towards the centre of the bridge to allow of subsequent settle-
ment ; this is technically called the camber, and should be about
-^\ of the span.

CHAPTER XIV. — BEIDGES. 59

150. RefTulations for the passage of troops over field bridges Precau-
are laid down in " Combined Training," 1905, Sec. 27. ^ions to be

With the officer in charge rests the responsibility of no j'^^^ J^^ ^^
physical obstacles occurring to cause checks or crowding on bridges.
the bridge itself.

The passage of troops o-ff a bridge should be always
expedited, their passage on to it carefully regulated, and, when
necessary, checked by material obstacles.

The officer superintending the construction of a bridge
is responsible that it is strong enough to support the weight
it is intended to carry. To prevent it being over-strained he
should place a signboard at either end, stating the greatest
permissible load, thus : —

" Bridge to carry infantry in fours."

" Bridge to carry infantry in file."

" Bridge to carry guns not heavier than 13-pr."

Trestle Bridges.

151. Trestles made of spars lashed together \vith rope or Lashetl
wire may be of three kinds — two, three, or four-legged. spar

The ordinary form of two-legged trestles is shown in PL 50, *^^^stles.
Fig. 2.

152. To make trestles for a particular bridge the centre line of Order of
the bridge should be marked out on either side of the gap, and a '^ork.
section of the gap laid out on flat ground showing the depth of

the gap at each trestle (two sections, if the depth on one side of
the bridge is different to that on the other). For each trestle
the position of the lashing on the transom is dependent on the
width of the roadway, and the lashing on the leg dependent on
the depth of the gap allowing an outward splay of -f- The
ledgers are usually lashed on about 1 foot from the bottom of
the leg, parallel to the transom, their point of lashing depending
on the length and splay of the leg. For a muddy bottom

CHAPTER XIV. — BRIDGES.

Placing
and

bracinn;
trestles.

Three-
legced or
tripod
trestles.

the ledgers should be close to the butts, so as to take the mud ;
for a rocky bottom they should be high enough up not to
touch.

Square lashings {see Sec. 129) must be used. The braces
are put on the frame with both butts and one tip on the
same side, the second tip on the reverse side ; their butts
can be lashed simultaneously with the ledger and transom.
The frame must then be squared by testing the diagonals,
measuring from the centre of the ledger lashing to the centre
of the transom lashing on the opposite leg, and the frame must
be adjusted till these measurements are equal. The braces can
then be lashed at the tips and crossing point.

If the timber is weak both legs and transom can be doubled.
Ledgers and diagonal braces can be of light material, as little
strain is brought upon them, but they should be well lashed.

When the water is very shallow the trestles can be carried
out and placed by men working in the water. When the water
is too deep for this they can be carried on to the bridge and
lowered feet first down inchned spars to their final position,
or taken out on rafts and by means of guys taken to shore
tipped up into position.

Two-legged trestles are kept upright by lashing the road-
bearers to the transoms and by cross-bracing from each trestle
to its neighbour {see PI. 49, Fig. 1), the nearest trestles to the
banks on either side being rigidly connected thereto by light
spars lashed to the tips of the legs and to bollards on the bank.
These light spars are put on before the trestle is launched,
and help to get it into position, they also serve as handrails
when the roadway is placed.

153. PL 51. Fig. 1. shows three-legged trestles, two of which
are required for the support of a single transom ; to make them,
it is best to lash two legs together by a sheer Ipshing, open them
out, and then add the third leg or prypole (see Fig. 2) ; the
trestle must t' en be up-ended, the feet placed on the angles of
an equilateral triangle with sides of about half the height, and
thr^e light ledgers attached.

The advantages of tripod trestles are that they utilise light
material, will stand without bracing, and admit of more ready
adjustment, raising or lowering, of the roadw^ay than either

TRESTLES

PLaJ^iS]

s/as.s .OS .

Wel («r k Gr«h««ii. Lflf U rte^^^Oon

Opposite jJC^Mf^ SO.

BRIDGING EXPEDIENTS.

J^i^.1.

If^^i.os.

Opposite pn^ 6/.

CHAPTER XIV. — BRIDGES. ol

of the other forms ; they are, however, unsuitable for aa
uneven bottom, and extremely difficult to place, excepting by
actually carrying them into position. They are usually
placed from rafts when working over water, and their legs must
be weighted.

154. Fig. 3 shows a four-legged trestle ; it is made of two Four-
frames similar to two-legged trestles, locked at the transoms, legged
and connected by short ledgers at the feet. One frame must trestles,
therefore be made narrower than the other. The inclination

of the legs should be such that the breadth of the base on which
the trestle stands should not be less than half the height. The
legs must also have an outwards splay of |.

Four-legged trestles can be made of fairly light material, and
will stand without bracing. They are consequently useful
for small bridges of two bays,' requiring one central support,
and as occasional steadying points in a long bridge of two-
legged trestles.

When a carpenter's tools are available, trestles may be
made with iron fastenings ; they are more durable than those
made with rope. Figs. 4 and 5, PL 51 are examples. Fig. 5 is
especially useful when only light timber is available.

155. Communication may be rapidly established across a gap BridiJing
by the method shown in PL 51, Fig. 6. In Fig. 6 two spars expe-
are rested about their centres on the transom of a narrow <lients.
light trestle and launched across. The transom should be
lashed at such a height that when the trestle is inclined
forward so as to land the tips of the spars on the opposite

bank, the transom will be on a level with the two banks.
Planks can then be laid on the spars to form a foot bridge.

156. In PL 52 are shown various expedients which can take Sub-
the place of regularly constructed trestle bridges. Fig. 1, a ^titutes
roadway laid on carts. for trestle

Fig. 2, piers of crib work. This is a specially useful form of " ^^^*
pier when timber is plentiful and other stores deficient. If
used in water a tray should be formed in the bottom of the
crib, which latter can be towed into position, weighted with
stones and sunk.

Fig. 3, small gaps crossed by means of brushwood, in the
form of gabions or fascines.

62 CHAPTER XIV. — BRIDGES.

Fig. 4 shows a method of roughly trussing a log, frequently
used in Canada.

Floating Bridges.

157. In selecting a site for a floating bridge it should be
remembered that the bed of the river should afiord good holding
ground for anchors if required.

The use that can be made of islands to economise material
should be noted.
Koad\>ay. 158. The roadway of floating bridges is similar to that
already described in Sec. 141 ; wide roadways are preferable
to narrow ones, on account of their great steadiness.
Buoyancy. 159. Each pier must have enough available buoyancy to
support the heaviest load that can be brought on to one bay
of the bridge. No extra allowance need be made if the load
is live.

The length of the piers should be at least tw4ce the breadth
of the roadway for the sake of steadiness, and they may be
connected together at their ends by tie baulks or lashings.

The ivaterway between the piers should never be less, and
should if possible be more, than the width of those piers.

Floating piers may be made from specially constructed
pontoons, boats, casks, or timber rafts ; inflated skins, or
anything that w^ill float, may have to be resorted to on emer-
gencv.
Boats. 160. Open boats should not, except in sluggish water, be

immersed deeper than within 1 foot of the gunwale, and a
still larger limit of safety wall be required in rough water or a
violent current. They should be placed in bridge " bow on "
to the current, and slightly down as the stern ; or if the
river is tidal they must be placed alternately bow and stern.

If the boats be not each buoyant enough to form a pier,
they may be used in pairs (Fig. 2. PL 53). The sterns are
lashed together, and the spars AA^ BB| are held over the side ;
four 2-inch ropes at AB, CD, CiDi, A,Bi, are passed under the
boats and secured to the poles, and four double ropes are
passed round the latter at the same points and cross over the
boats ; these ropes are racked up tight. Crosspieces, MM, are
then lashed to the poles and thwarts, and blocks on the thwarts

I'Uilf. S3

BOAT PIERS

^^.;.

^^j^

SexitLon. Jl.JB.

J^O/.Z.

^^•10^

3 fiddle^ ^eearv

W^Thj/^'ccyV

SI a 6. B 05.

W«ller46fah«m.L'* Lirfto,Lon«Jon.
Opposite' pcLge 6Z .

^,1

Plate 54

CASK PIERS

rtavruda

SlUL^S

-^F3:3ir

^rTvrrvf If- ^:^l 7^

Szde JElevaJturn. 2njg 8 ^^-^

Pg^"^

^SS.Z.05.

Welleri Graham. L'* LirhoLondon

Opposite- paqC'SS

CHAPTER XIV. — BRIDGES. 63

at EE support the saddle beam, which is lashed to the thwarts
and to the stern rings of the boats.

Few boats, with the exception of heavy barges, are strong
enough to allow of the baulks resting on their gunwales.
A central transom should be improvised, which can generally
be done by resting a transom on the thwarts, and blocking them
up from underneath, thus bringing the weight directly on
to the kelson. This arrangement is shown in Fig. 1, PI. 53.

161. The available buoyancy of a boat may be (most simply) Buoyancv
determined by loading it with unarmed men to such a depth of boats,
as is considered safe, usually within 6 inches of the gunwale

in sluggish streams and 1 foot in rapid, and multiplying this
number by 160. The result gives the available buoyancy in
pounds.

1 62. The usual method of forming a number of large casks Piers of
into a pier is shown in Figs. 1, 2, and 3, PL 54. The casks are ca»iks.
laid bung uppermost, and Hned, two baulks technically known as
gunnels (GG) are placed over the ends, and the slings (SS)

are secured under the ends of the casks to - the gunnels.
Between each pair of casks, on each side, a brace is secured
on the shng, and is then led round the gunnel ; the opposite
braces are crossed and secured again on their own side.

A knot must be made as shown near the standing end of
the braces to prevent tbe crossed parts shpping. Care must
be taken that the braces are pulled taut ; this is best done
by rocking the barrels, at the same time hauling in the
slack. For large piers the shng should be 2J-inch to 3-inch
rope, the braces can be of IJ-inch rope. (For a detailed
description of this method, see Part II.).

163. Fig. 4 suggests a method useful for smaller casks.
Small piers of three or more casks, aa, bh, cc, being made as
above described, and subsequently united by two large
gunnels, X, X.

164. Figs. 5 and 9, show another method useful for medium-
sized casks. The braces are first fastened to a gunnel and
stretched out perpendicularly to it ; the casks are then placed
in two rows, end to end, on each side of the baulk and over their
own braces. On the casks are laid two gunnels, loosely lashed
together at the ends and at one or two intermediate points,

64 CHAPTER XIV. — BRIDGES.

the distance between them being less tlian a bung diameter,
the braces are then secured to the gunnels by two round turns
and two half-hitches ; the lashings connecting the gunnels
are then racked up, and finally the two at the ends are secured
to the underneath baulk by lashings, which are also racked
up taut. Other methods can be readily devised according to
the material available, e.g., the cask can be completely
enclosed in a wooden framework, the parts of which are
lashed or nailed together {see Figs. 6, 7, and 8.
Tie baulks. 165. Piers of casks when in bridge should always be rigidly
connected to each other at their ends by tie baulks, which must
be lashed to both gunnels of each pier ; the roadway baulk?
can then be laid, without lashing if rectangular ; they should
rest on both gunnels of each pier.

If, however, the baulks are round, or there is likely to be much
sway on the bridge, and especially for animal traffic, it gives
additional security to lash, at any rate, some of the baulks
both to each other and their overlap, and also to the gunnels.
Headless casks must be enclosed vertically in a specially
prepared framework.
To form 166. To form a raft, the logs should be placed side by side,

a raft thick and thin ends alternating ; they should then be strongly
secured with rope, and, if possible, by cross and diagonal pieces
of timber fastened by spikes or wooden trenails ; or the logs
can themselves be connected by dogs.

If a raft is to be used as a pier in a bridge, it will frequently
be necessary to place the logs in two layers, to avoid obstructing
the waterway. A central raised transom must be used.
The up-stream end of the raft may, with advantage, be slightly
convex.

Rafts are most easily put together and manipulated in the
water.
Anchoring 167. Anchors are of various weights. For ordinary bridge
of bridges, work 5G-lb. anchors, with a reserve of 112-lb. anchors, will
generally suffice for moderate streams.

The cables are generally of 3-inch rope. The length of cable
" out " should be ten times the depth of the stream, and rarely
less than 30 yards. The cable is attached to the ring of the
anchor (PI. 55, Fig. 1) by a fisherman's bend ; a buoy should

I'/'rt^> 55.

ANCHORS

^^.^.

CrownX — ^

IFigr.S

Fi^.^.

5/86. S 05.

Wwlertirfltism.L" Li>t>ci,Londoo

Opposite pcfj^e- 65.

CHAPTER XIV. — BRIDGES. 35

be attached to the anchor by a buoyline of l-inch rope, fastened
to a ring of the buoy by a fisherman's bend, and round the
crown of the anchor, with a clove hitch split by the shank,
and two half-hitches round the shank. The use of the buoy is
to mark the position of the anchor and serve as a means of
raising it.

As a rule there should be an up-stream and down-stream
anchor to every second pier of a floating bridge.

If anchors are scarce, one may be made to serve for two
piers by attaching two cables to it on the down-stream side
of the bridge, as shown in Fig. 2.

Care must be taken before heaving an anchor overboard to see
that it is carefully stodced.

Timber raft« and cask piers being, as a rule, a greater strain
on anchors than boats or pontoons.

In d very rapid current, anchors can seldom be trusted.
The bridge must then be secured to a hawser stretched across
the river " up-stream.*' Wire rope is convenient for the purpose
(Fig. 3). Short bridges can be kept steady by cables stretched
from the piers to the banks, up and down stream (Fig. 4).

168. The following are substitutes for anchors : — Makeshift
Two or more pickaxes lashed together. anchors.
Heavy weights, such as large stones or railwav irons ;

the latter are best when bent.

Nets filled with stones— remarka^bly effective on rocky
bottoms.

169. X bridge can be formed by booming ov.t, i.e., the head Methods
of the bridge already constructed is continually pushed out o''^"o?''^'ng
into the stream, fresh materials being added at the tail. This ?°^^^^°
method economises the distance the materials have to be BoomiiT^
carried, but necessitates a certain number of men working out.

in the water, and cannot be used vrhen the banks are steep,
and there is deep water close in shore, as for instance, in the
case of a wharf wall.

In for thing up. material is continually added to the head Forming
of the bridge, the tail being stationary. This method is up.
uninfluenced by the nature of the banks, no men being required
to work in the water. Its only drawback is the distance the
roadway materials have to be carried.

(5289) T,

CnArTER XIV. — P.TIIDGES.

Bafting.

Swinging.

Forming
cuts.

Protection
of floating
bridges.

Passage of

heavy

artillery.

Passage of
arms and
ammuni-
tion.

Ferries
and flying
bridges.

In rafting, the bridce is put toiretlipr in difTeront pcrtionp or
■rajt? along the shore, each raft consisting of two or morn piers,
which rafts are successively warped, rowed, or towed into
their proper positions in bridge.

This method has the advantage that a large number of men
can be employed simultaneously ; and if secrecy b?5 an object,
the various portions can be constructed at some distance
from the eventual site of the bridge, and a favourable oppor-
tunity seized for its construction.

In swinging, an entire bridge is constructed alongshore,
and then swung across with the stream.

A long bridge can be constructed by a combination of two
or more of the above methods.

If a bridge has to remain down for some time, arrangements
must be made for the passage of the river traffic, which can be
done by having two or more rafts, at the centre of the bridge,
arranged for " forming cut " as required ; or the two halves
of the bridge may be swung, to afford the requisite passage.

170. Arrangements must always be made, up-stream, for
the protection of a bridge from damage by floating substances,
either by a boat patrol or by stretching a net or some inter-
cepting obstacle acioss the stream.

171. If heavy siege artillery has to be passed over a broad
river it will generally be most economical of m.atcrial to con-
struct the bridge of only sufficient strength for the ordinary
traffic, and to warp the guns across on rafts constructed of
sufficient strength for the purpose.

172. To keep rifles and am.munirion dry when men swim
across a river, small rafts can be made of w;iterproof kitbags
filled with straw, blown-out ma'^aks (water-skins), cooking
kettles or any similar vessels, which should be placed mouth
downwards.

The simplest form of permanent ferry consists of ropes
stretched across the river by means of which rafts can be
sheered or hauled backwards and forwards from bank to bank.
If it be not convenient, for the sake of traffic or other reasons,
to stretch a rone across the stream, recourse may be had, if
the current is rapid and regular, to a flying brid<7e, which is one
in which the action of the current is made to move a boat or

P(xrf€.^e.

FORDS & FLYING BRIDGES

Stream^

^^*^ tP- 7^^-^.

VMIerii&r»t>a« 'C* li>(M.Lon(ton

()ppcsxjb& Jiaxfp^ 67,

CHAPTER XIV. — BRIDGES. G7

raft across the stream by acting obliquely against its side,
which should be kept at an angle of about 55° with the current.
(PI. 56, Fig. 3.)

Long narrow deep boats with vertical sides, to which lee
boards can be attached, are the best for the purpose, and
straight reaches the most suitable places, as they are generally
free fiom irregularities of current or backwaters.

The cable, which should, if possible, float, such as coir rope,
can either be anchored in mid-stream, in which case the raft
can swing between two landing piers ; or two cables may be
used, one anchored on either bank, as shown in Fig. 2. This
method requires less skill in manipulation, but necessitates
two cables and four piers.

The length of a swinging cable should be one and a half to
two times the breadth of the river, and it will work better if
supported on intermediate buoys or floats to prevent it from
dragging in the water.

Telegraph wire, buoyed up as above, on meat tins, makes
a good swinging cable. Another way is to stretch a wire
cable across the river, and arrange the raft so as to travel
along it {see Fig. 4, PI. 56).

173. The following depths are fordable : — • I'unls.

For infantry, .3 feet.
For cavalry, 4 feet.
Artillery, 2 feet 4 inches.
Gravelly bottoms are best, sandy bottoms are bad, as the sand
gets stirred up, and the depth of water thus increases.

Fords should be clearly marked by long pickets driven into
the river bed above and below the ford, their heads being
connected by a strong rope. It is well to mark the pickets in
order that any rise of the water may be at once evident.

The depth of a river is generally most uniform in straight
parts ; at bends the depth will generally be greater at the
concave bank and less at the convex. Thus, in PI. 56, Fig. 1,
the depth will probably be above the average at C and F,
and there will be shallow spits at D and E.

For this reason a river which is not anywhere fordable straight
across may be found passable in a slanting direction betweer
two bends, as at A B, Fig. 1.

(5289) E 2

CHAPTER XV.— CAMPING ARRANGEMENTS.
Cooking.

Field
kitchens.

Covered
kitchen.

Expedi-
ents.

Kettles.

174. To cook for a large party, the most economical method
is to dig or build up a long trench for the fire, place the kettles
on it (its width not being sufficient to yllow them to drop into
it), and cover up between them with stones and clay, that the
fire, fed from the windward end, may draw right through.
A chimney can be built at the other end to increase the draught.

The section of a typical trench for this purpose is shown in
Fig. 1, PI. 57.

The chimney can be built of sods, and is supported where it
passes over the trenches, by flat stones, slates, wood covered
with clay, &c. The inside of the trenches and of the chimney
may be plastered with clay, which makes them last longer.
Several such trenches may be combined, as shown in Fig. 2,
to form what is known as the "parallel or rectangular kitchen,
or three trenches may converge to one flue, as shown in Fig. 3,
forming what is known as the broad arrow kitchen.

175. The gridiron kitchen (Aldershot pattern) is shown in
PL 58.

176. PI. 57, figs. 4 and 5, gives details of a covered kitchen,
suitable for standing camps. The roof may be covered with
tarpauhns, or in the manner described in Section 193.

177. For a small party the cooking may be done by digging
a shallow trench, in the direction of the wind, to contain
the fuel. Small pieces of iron will be found very useful to
support the kettle. Another way is not to excavate the ground
at all but to build up two rough walls of stones on the top
of which the kettle is placed.

The simplest and best arrangement for cooking in the field
for any party over 20, especially if the stay in camp is only
for one night, is to place a porportion of the kettles on the
ground in two parallel rows about 0 inches apart, handles out-
wards, block the leeward end of the trench so formed w4th
another kettle, lay the fire and place over it one or two rows
pf kettles resting on those already placed in position {see PL 59).

JPlccte.51.

KITCHENS.

riy.z

Seotvo

RECTANGULAR

CvoJcj f»f V'.ft-i BROAD

3 A? ftten.

ARROW

COVERED KITCHEN

\f^'\\ Tr^.^. i'^:^!^

Ti^.5

WeU«r«,«ireh««.L'* liH>O.U>«««r

Opposite pciqe S8,

J^lat^5ti

GRIDIRON KITCHEN

I'Zjr^.?.

up!'^^ a

¥:r ii

.^f1

^!-f-'?---:-jf-*'---^-'ii

1 — n

/\ /\ /\ /\ /\ /\ /

\J\

^rervchy 36 '^2'' X 7 'S oi&^pff

JPVy.^.

ALDERSHOT OVEN

J^z^.S

cae 8 OS

welter &€r«h4n.L" LitftoLondon

7h foZlcnv plate 37.

Plate f 3.

COOKING IN THE FIELD

Fiff.l.

>.^^> -^'■

™.^.'-. " -~>tK*/

V/eller<<CrBtiafn L" LirNc lor.do'^

2« foUcrrv pluJ:^SS

FIELD OVENS

^iff.4:

Sectlorv CU

>--->■

•^jTjjr.^.

-i* ♦,'

^^-?

:Pljajv

-i

j^.S.

«« g-

Wef1tr«i6f«h«m, L'f Lirho.Lon^on
To fblZo^ plate 59.

CHAPTER XV. — CAMPING ARRANGEMENTS. 69

Mess tins can be arranged similarly, but in their case not Mess tins,
more than eight should be used together.

178. The simplest form of a field oven consists of a hearth Field
sunk below the ground surface, with, an arch formed by a hurdle o^^^ns.
or sheet iron {see ?1. 60). The two gable ends are formed
with sods. The whole of the interior of the oven is well
plastered with cowdung and clay. The hurdle, well plastered

on the outside with cowdung and clay so as to leave an arch
when it burns away, is covered with earth from the excava-
tion. The entrance to the oven is closed either by a hurdle
plastered with '^]ay or simply by sods.

This oven is specially suitable for making bread, and will
bake for about 150 men at a time.

Figs. 5, 6, and 7 show an oven with a flue underneath an
iron hearth. The oven is first heated by lighting a fire inside
it, and this is afterwards raked out and pushed into the flue
below to maintain the heat. It is a very useful oven for
baking or keeping men's dinners warm. The service oven,
Aldershot pattern, should be fixed up without the flue, but
placed on a prepared flattened site.

Latrines.

179. Latrines should be made as soon as troops arrive on Latriues.
the ground ; a small shallow trench will suffice for one night ;

and should be invariably filled-in in the morning, before the
troops march oS. In standing camps latrines may be made
with seats, the seat being a pole (see Figs. 1 and 2, PI. 61) ;
additional comfort may be given by adding a top pole
to form a back, as shown. Other forms are shown in
Figs. 6 and 7.

In order to keep out flies latrines, where practicable, should
be closed in and made as dark as possible.

Latrines should be constructed to seat if possible at least
5 per cent, of the troops, 1 yard per man being allowed.
The trenches must be narrow and deep to prevent the contents
being blown about. When natives are employed special
latrines for them are necessary.

70 CHAPTER XV. — CAMPING ARRANGEMENTS.

It is very important that a couple of inches of the driest
earth obtainable should be thrown over the soil twice daily ;
this, if carefully done, will prevent all smell and tend to
prevent flies collecting. The earth may be dried by pihng it
close to the trenches of the field kitchens. Lime or charcoal
may also be used to deodorise the soil in the trenches.

On leaving camp the site of latrines should be carefully
marked.

Too much care cannot be bestowed in selecting the site of the
latrines; since flies are very active agents in propagating
diseases, latrines must be placed well aw^ay from cook-houses.
Care must be taken that no filtration from them may reach the
water supply.

Water Supply.

Wator 180- Each man requires for drinking about 3 to 4 pints per

supply. diem; for drinking and cooking, 3 to 4 quarts; for drinking,
cooking, and washing, 3 to 4 gallons.

Each horse requires for drmking 5 to 10 gallons, according
to work and chmate, soft water being the best ; for cleaning,
6 to 8 quarts (which may be salt). Each mule or ox drinks
G to 8 gallons ; each sheep or pig 6 to 8 pints. These are
minimum quantities.

Horses drink about I J gallons at a time.
In calculating troughing, allow each horse five minutes
at the trough.

^.B.—See also " Combined Training," 1905, Sec. 43.
One cubic foot of water = G^ gallons (a gallon = 10 lbs.).
Pleasure- 1 81. The rough average }4eld of a stream may be measured as
iiient ot follows : — Select some 12 yards or 15 vards of the stream

..; -.1 .1 ...

where the channel is fairly uniform, and there are no eddies.
Take the breadth and average depth in feet in three or four
places. Drop in a chip of wood and find the time it takes to
travel, say, 30 feet. Thus obtain the surface velocity in
feet per second. Four-fifths of this will give the mean velocity,
and this multiplied by the sectional area in square feet will
give the yield per second in cubic feet of water.

quantity
ivquiivd

yield.

rCucteGJ

LATRINES

S' 0 3 0 rr

. 4-. M

J-^g.5.

Section^ 6/./^.

"sias 8.0S

Opposite p<^^ 70

CHAPTER XV. — CAMPING ARRANGEMENTS. 71

The source of the water supply should be carefully in- Source,
vestigated, and measures tiiken to prevent the pollution of the
water en route to the drinking supply.

182. In the field the supply is usually obtained from sources
which are at once available, such as streams, ponds, or existing
wells. In default of these it may be necessary to sink wells
and make reservoirs.

Surface springs should be sought for in hollows, at the Surface
foot of hills, where the earth is moist or where the grass is springs,
unusually green, where the thickest mists rise in the mornings or
evenings, &c.

183. If the supply be from a lake, pond, or stream, separate Protection
watering-places for men and animals must be marked out and <^t" tlie
sentries posted. Stagnant water, as in a pond, is apt to be ^^^^^^^ ^'
contaminated by large numbers of animals going in to drink ;

and even in a stream, when many animals are drinking, those
below get foul water. If possible, therefore, the water should
be drawn from the source and run into drinking troughs ;
these are best made of canvas or of boards ; but trenches lined
with puddled clay answer the purpose.

1 84. The overflow from the troughs must be carried ofi with
the surface drainage. The sites of the troughs should, if
possible, be paved and drained for a width of 10 feet, and should
be so arranged that the animals may move to and from them
without confusion or crowding, arriving from one direction
and leaving in another.

Each horse occupies laterally 4 feet ; if possible, all the horses
in a camp should be able to be w^atered in an hour.

When troughs cannot be made, the banks should be cut
down, and a hard bottom formed on the ramp to prevent the
animal from sinking in. A barrier may be placed in the pond
to prevent them from going out too far. The water should not
be less than 5 inches or 6 inches deep where beasts are to drink.

185. In a stream the men should draw w^ater above the place Supply
for the animals ; while washing, &c., should be done below, ^'"'^"^
and drainage should enter below the others as far down stream ^ '**''^"^*-
as possible.

Barrels sunk in the bed of a small stream afford convenient
dipping places.

from
spring

72 CHAPTER XV. — CAMPING ARRANGEMENTS.

Supply 186. If the supply be from springs, each springhead should be

opened up and surrounded by a low puddled wall to keep out
surface water. Casks or cylinders made of brushwood, like
gabions, make good linings for springs. After they are placed,
puddled clay may be worked down between the banks and the
cask or cylinders. The overflow may be received into a suc-
cession of casks or half barrels (which may with advantage
have their insides charred) let into the ground close together,
the overflow from the first passing into the second, and so on ;
or deep narrow tanks with puddled sides may be constructed
to catch the overflow.

Water from small ponds and shallow wells should be avoided,
if there be a choice.
P^- 187. The lift and force pump is in most general use in the

service. It is worked by two men. It can lift water from a
depth of 20 feet to 28 feet, and force the water to a height of
60 feet from its former level, dehvering 12 gallons per minute.

Purifying Water.

Boiling. 188. The best method of purifying water is by boiling.

It gets rid of temporary hardness, renders dissolved organic
matter harmless, and when carried out effectually practically
destroys all micro-organisms. The water should be kept at the
boil for at least five minutes.

Boiled water should be aerated before use. This can be done
by passing through a sieve. Improvised methods can be
arranged according to the means at disposal. Empty biscuit
tins pierced with small holes suspended over a storage tank
do very well for this purpose.

Care is necessary to prevent the addition of fresh impurities
during aeration and distribution,
riltraiion. 189. As it is not always possible to provide means of boiling
water on a large scale, filtration must be resorted to.

Formerly mechanical filtration only was attempted and a
clear sparkling water was considered good. Efforts are now

CHAPTER XV. — CAMPING ARRANGEMENTS. 73

directed to remove meclianical and chemical impurities as
well as micro-organisms. Several filters have been brought
before the public, all claiming to effect these purposes. The
type most familiar is the " Berkefeld " filter. These filters,
if treated with care and strict attention to detail, work satis-
factorily. Their chief defect is a very slow dehvery when water
containing a large percentage of suspended matter is used.
The porcelain candles become almost impervious when coated
with fine mud and constant cleaning is necessary. This,
however, is an easy process.

Dirty water should be strained before filtering. A good
method is to tack a sheet on to a wooden frame so as to form a
bag or basin ; put a couple of handfuls of wood ashes in the
bottom, and then pour on the water, allowing it to percolate
into a receptacle beneath.

190. Chemicals are sometimes added either : {a) to precipitate Addition
suspended matters ; [b) to remove hardness or ; (c) to oxidise ^^
organic impurities, {a) Muddy water may be cleared by adding ^ ^^^^^^^ ^•
alum. Six grains of crystallised alum per gallon is sufficient.
It should be added some hours before the water is required.
[b) Water can be softened by the addition of Hme water for
drinking and carbonate of soda for washing purposes. The
latter is unsuitable for drinking water as it gives an unpleasant
taste, (c) Permanganate of potash (Condy's fluid) removes
offensive smell from water and to some extent oxidises dissolved
organic matter. It should be added until a faint tint remains
permanent. It has not a disagreeable taste.

Shelters and Huts.

191. Bivouacs are but seldom resorted to except in the neigh- Bivouacs,
bourhood of an enemy, when miUtary rather than sanitary
considerations are of primary importance. The following are
the chief points to borne in mind in determining the sites
for bivouacs : —

In the presence of an enemy, tactical considerations, e.g., Choice of
favourable ground for defence in the event of attack, conceal- ground

74 CHAPTER XV. — CAMPING ARRANGEMENTS.

ment, facilities of protection, and consequently, economy
in outposts are of the first importance. The comfort of the
troops, in conjunction with sanitary conditions, is the next
consideration.

A good water supply is essential, but considerations of
safety may necessitate a camp or Livouac being placed at
some distance from it. Other points to be considered are the
facilities which a site offers for obtaining shelter, fuel, forage
and straw.

The site for a camp or bivouac should be dry, and on grass
if possible. Steep slopes should be avoided. Large woods
with undergrowth, low meadows, and newly turned soil
are apt to be unhealthy. Clay is usually damp. Ravines
and watercourses are dangerous sites, as a sudden fall of
rain may convert them into streami.s.

If the occupation is to be of a permanent nature, as
in investment warfare and the defence of strategical points,
the men ought to be hutted.
Tem- 192. PI. 62 suggests methods of forming simple shelters,

porarv Yis. 1. Two forked sticks driven into the ground with a pole
restmg on them ; branches are then laid resting on the pole,
thick end uppermost, at an angle of about 45"^, and the screen
made good with smaller branches, ferns, &c.

A hurdle may be supported and treated in a similar way.

Fig. 2. A waterproof sheet, blanket, or piece of canvas
secured by poles and string.

Fig. .3. A tent (Tabri for four men, formed with two blankets
or waterproof sheets laced together at the ridge, the remaining
two blankets being available for cover inside.

Fig. 4. A wall of straw or reeds nipped between two pairs
of sticks, tied together at intervals.

Figs. 5 and 7. Sentry box for standing camps.

When no other materials than earth and brushwood are
available, a comfortable bivouac for 12 men can be formed
by excavating a circle with a diameter of 18 feet, or there-
abouts, and piling up the earth to form a wall 2 feet or 3 feet
high. The men lie down, like the spokes of a wheel, with their
feet towards the centre. Branches of trees, or brushwood stuck
into the wall, improve the shelter.

shelters.

L V

^W^ex^

BIVOUACS.

:Fzff.i.

SFig.Z'.

STteZce?^ Terut

:Fcgr.3.

^^■^'

^rv:>7ft. of T-ourLdySooo

sias 3. as

Opposi/^. page 74

Plojte 63.

HUTS.

^7^anrk4s.

THATCHING

?ra^

siee i .OS.

Plate ^4

HUTS

\^^ : ^'.'n <■ ' -"', f-, f I -* ■? -, » ' -r^ '^'^

pieces

-?'"Y<y. ^.

JLoq. SuJ(>

J±^Z,ou7y

SIB9. a.os.

WcilerAGratiam. LH Litho. London.

CHAPTER XV. — CAMPING ARRANGEMENTS. 75

193. The materials of which huts are made depend upon the Huts,
resources of the locality, and are principally brushwood, logs,
straw, reeds, clay, turf, and stones.

The best form of hut is generally rectangular in plan, with Plan,
sufficient width for two rows of beds, and a passage down the
centre, but, where the material available is of small size,
one row of beds may be provided, or the hut may be made of
circular form. A width of at least G feet should be allowed for
each row of beds, and the passage may be from 2 feet to i feet
wide.

The accommodation may be calculated on active service Accommo.
at one man per foot in length of the hut, when there are two ^^^^o"-
rows of beds, and one man to every 2 feet when only one row
on beds.

Fig. 1, PI. 63, shows how the ordinary 6-foot hurdles may
be arranged to form a hut. A fascine at the ridge, with thatching
of straw, reeds, &c., may be used as roofing.

Hurdles may be made of special dimensions for hutting Hurdles,
purposes. Fig. 2 shows how a hurdle 10 feet long (measured
on the curve) may be made into a hut. The hurdle is constructed
on a curve slightly flatter than that it is intended to have,
so that it is necessary to spring it together to get it into position.
It is then secured with pickets, and covered with sods, or daubed
with clay in the manner described in Sec. 195. The ground
forming the floor of the hut may be sloped as shown before
putting on the hurdles.

Hurdles for hutting purposes should have the ends of the
pickets cut off as close to the web as possible, so as to leave no
gaps between them.

194, When brushwood of 2 inches or 3 inches diameter and Brush-
14 feet or 15 feet long is available, a hut for a double row of wood,
beds may be made as in Figs. 3 and 5.

The section of the hut being decided on, is laid out on the
ground ; from this the length of the rafters is obtained.
Each side of the roof is then made separately on the ground
as follows : —

Poles of 2 inches to 3 inches diameter are laid on the ground
parallel to each other, from 18 inches to 2 feet apart, as aa,
in Fig. 4, PL 63. These form the rafters. On the slope of the

CHAPTER XV. — CAMPING ARRANGEMENTS.

ixiaterial.

Passa*.

rafters, and at right angles to them, hght rods or laths, hh.
from -J inch to I inch thick are laid, the uppermost one being
at such a distance from the bottom of the poles as will allow
the frames^ when made, to lock at the desired height above th^^.
ground, the lowermost one being within a few inches of the
bottom, and the interval between being divided according to
ll-e length of the thatching or covering material. The distance
apart of these laths should be slightly less than half the length
of the covering material, so that the latter may be supported
i.t three points. With good wheaten straw the !nterv:il may
be from 12 inches to 1^ feet. At each point of crossing the
laths and rafteis are secured by a short length of one strand
of spun yarn, and the frame thus made is afterwards stiffened
by diagonals lashed underneath.

The roofing material, which may be unbroken straw, rushes,
long ferns, &c., Is now put on. Commencing at the bottom,
a layer 4 inches or 5 inches thick is equally laid over the three
lowest laths, ears or tops downwards ; it is here secured by
a light rod or thatching piece tied with spun yarn at intervals
of 2 feet or 3 feet to the second lath from the bottom. A second
layer is now put on one lath higher up, and is secured in a
similar w^ay to the third lath from the bottom, and so on
until the top is reached ; the last layer projecting over the
top lath, so that when the frames are locked the ends may
be twisted together to keep out wet (Fig. 6, PI. 63). When
both frames are ready they are raised and locked, as in Fig. 3.
Forked uprights and a ridge piece may be added to stiffen the
roof.

Each side of the roof may be made in one piece, or if large
and inconvenient to move, in two sections. The ends of the
laths should project about 2 feet beyond the extreme rafters,
and are supported by the framework forming the Gable ends,
Fig. 5. The latter are made and thatched in a similar way to
the roof, and simultaneously with it, an opening being left
for a door.

In order to give additional headway, the passage may be sunk
as in Fig. 3, with steps at each end, the earth being thrown
to the eaves as additional protection, and to give more head
room when lying down. In very cold weather the whole
interior of the hut may be excavated, fireplaces constructed

CHAPTER XV. — CAMPING ARRANGEMENTS. 77

as in Fig. 1, PI. CA, and, if the rafters be strong, some of the
excavated earth may be thrown on to the top of the roof,
a collar tie being added to strengthen it.

Huts may also be thatched by forming the straw or grass into Panels.
panels. The straw in moderately thick layers is doubled
and nipped near the centre between two rods, one above and
one below, which are tied tightly together at the ends and at
intervals of about 6 inches.

The panels formed thus are tied on to the roof, being placed
so as to overlap hke large slates.

195. Walls may be constructed of ivattle and daub, i.e., Wattle
continuous hurdle work daubed over on one or both sides with «^f^ daub
clay, in which is a proportion of any fibrous substance, such ^'^*^'^'

as straw, grass, horse hair, &c., chopped into short lengths
to prevent the clay cracking and opening as it dries. This
mixture, which should be kneaded into the consistency of a stiff
paste, should be worked in with the hands. The sides should
be strutted at intervals to resist wind, and the roof mav be
carried on a ridge pole, which may be strengthened by uprights
in the centre, Fig. 3, PL 64.

196. When timber is abundant, log huts maybe constructed Log huts,
as shown in Fig. 4, PI. 64. No fastenings are required beyond

some trenails (wooden pegs) to secure the rafters to the top
logs. The roof may be made as already described, or the
covering material may be of slabs of wood, bark of trees, &c.

Bark may be got off trees in large strips by cutting round
the tree with a knife at intervals, say, of 4 feet ; then cutoff
width required, and beat with a flat piece of wood to detach
the bark from the tree.

197. When straw is issued for the troops to he upon, it may Straw
be made up into mats in the manner shown in Pis. 65 and 66. "^at?.

To make the mat shown on Fig. 1, pickets are driven into
the ground, the outside pickets being at a distance apart
about 6 inches less ttan the width of the required mat. A
crossbar, AB, is fixed about 2 feet from the ground. Several
lengths of spun yarn are then taken and made fast, about their
middle, to the crossbar, AB, at a distance of 5 inches or 6 inches
apart, and their ends made fast to the bar, CD, and to the
other pickets, as shown in the figure. Handfujs of straw

70 CHAPTER XVI. — HASTY DEMOLITIONS.

rather longer than the width of the mat are taken and pushed
in between the yarns, and the bar, CD, being alternately
raised waist high and depressed to the ground, and passed
inside and outside the end pickets, so as to form a hitch.
Finally, the sides of the mat are trimmed to the right size
by a sharp pair of scissors or a knife, and the yarns finished
off at either end with reef knots.
Straw The mat shown in Figs. 2 and 3 is formed by making

ropes. straw ropes and interlacing them on pickets driven into the
ground. If the straw ropes are carefully made, this makes a
more durable mat than the previous one. (PL 67.)

CHAPTER XVI.— HASTY DEMOLITIONS WITH
EXPLOSIVES.

Explosives.

Explosives 198. The service explosives available for hasty demoHtions
th^Tlrf" in the field are guncotton, gunpowder, cordite ; guncotton being
specially carried for this purpose. Dynamite may also some-
times be obtained locally.
Coin- For hasty demohtions guncotton is by far the best of the

parison of service explosives. Its chief advantages over gunpowder
Guncotton ^^^ *^^^ ^^^ equivalent effects a guncotton charge takes up
and much less room, and does not require the same amount of

powder. tamping* ; it is therefore much more easily and quickly placed
and fired, which is an important point in hasty demohtions.

* "Tamping" is covering tha charge over with earth or other material
so as to confine the gases at the commencement of the explosion, and thus
develop their force more fully.

Plate. 65.

STRAW MATS

MALAY HJTCH

STRAW ROPE MATS

^^J7- ^

^^.3.

J*Lckjsts G'apccrt.

"VTsr.

WielleriCrabam.Qf Utho.Loftdon.

Plaix.66,

MAKING STRAW MATS

jBfeM

Wel'erA Graham L^r Litho,London.
To foUvyv j>hx±c. S5

^Zcote, 67

MAKING STRAW ROPE

*&g i •S.

Welier fc Graham. Lff Lirti6.Loodon

Tc fellow pLocte 6^

CHAPTER XVI. — HASTY DEMOLITIONS. 79

Guncotton is also safer in transport and handling.

Cordite and dynamite are nearly as powerful as guncotton, Cordite
and have the above advantages over gunpowder, but are not ^"^
so safe m transport.

Where a lifting and shaking effect is required, gunpowder is
best.

Where a cutting or shattering effect is required, which is
most likely in hasty demolitions, guncotton, cordite or
dynamite are best.

Guncotton.

199. Guncotton, if steeped in water, will absorb about ProporMes
30 per cent, of its weight. ^^ ^^'©t

Wet guncotton does not ignite easily, and requires the ex- ^^"^^^^ °"'
plosion of a very large amount of detonating substance, such
as fulminate of mercury, in contact with it to detonate it.

Dm guncotton will not detonate in the open in small quantities Properties
if a light be set to it, nor if a bullet strikes it when not heated. °^ ^^^

It will detonate if it is struck between two hard substances. ^"^°°

If dry guncotton, especially when finely divided in the shape Sensitive
of fluff, becomes heated in any way (through friction or the T^^^I^.
heat of the sun) it is much more sensitive to percussion.

If a small quantity of detonating substance such as fulminate Means of
of mercury be exploded in contact with dry guncotton, it will detonating
detonate with great violence, and also cause the complete ^^^
detonation of any wet or dry guncotton with which it is in ^^^^^
contact.

The explosive force of wet guncotton is slightly greater than
that of dry.

So that for safety in transport, &c., in the field, the bulk of Carried
guncotton is carried and used wet in the shape of " slabs^ ^®^-
For detonating this, dry guncotton is also carried in the shape
of small discs called " primers''' The following table gives Primers,
the dimensions of the slabs and primers for land service : —

Slabs are issued in two sizes, about 6 inches square, weighing
1} and 14 lbs. respectively.

Primers are also issued in two sizes, weighing 1 oz and 2 ozs.
respectively.

80 CHAPTER XVI. — HASTY DEMOLITIONS-

The slabs have two holes in them, one to fit the 1 oz. primer
and the other the 2 oz. primer.

Cavalry pioneers carry special 1 lb. slabs.
Primers are carried dry in airtight tin cyhnders.
Use of wet For auger holes and for necklaces round timber, dry gun-
and dry cotton primers form the charge. Otherwise the charge is
S"^^^"'^"- always of wet slabs.

Details. The slabs can be cut without danger with a sharp knife or

saw, care being taken to press the guncotton between boards
whilst it is being cut to prevent it flaking away. There is
a special clamp in the R.E. equipment for doing this. The
guncotton should be kept damp.
]\reans of A charge of wet guncotton is detonated by means of the
detona- explosion of a dry primer in close contact with it. The primer
*'^®°' is exploded by means of a " detonator," the detonator is

detonated by means of either " safety " or " instantaneous
fuze," which is lit by a fusee or other means. (For details
of detonators, fuzes, see Sec. 205 and onward.)
Tinpro- If dry primers are not available, a piece of wet guncotton

rised can be dried hy exposure to the sun, and used instead,

primer.

Connect. 200. A charge is connected up for detonation as follows : —
ing up for '£\iq fuze (safety alone or safety wdth instantaneous) is cut
to the required length. The end to be ignited is cut on a slant
to expose as much of the composition as possible.

The end to be inserted in the detonator is cut straight across.
The straight cut end is then gently inserted into the open
end of No. 8 detonator, from which the paper cap has been
torn. This end of the detonator is then slightly bent (or with
new-pattern detonator, pinched) to make it grip on the fuze
and so prevent its being withdrawn.

(Cavalry pioneers carry detonators with a short length of
safety fuze ready fixed, the fuze having a piece of quickmatch
added to the end to facilitate lighting.)

The primer having been placed in close contact with one of
the slabs of the charge, either in one of the holes or tied to a
slab (see that the primer is dry), the small end of the detonator
is gently inserted into it so as to fill the entire length of the
hole. If the hole is too large, a piece of paper or grass must

detoiia
tion.

CHAPTER XVI. — HASTY DEMOLITIONS. 81

be wrapped round the detonator to make it fit tight ; if too

small, it must be enlarged with the rectifier* or piece of wood, Rectifiers.

but not with the detonator.

The charge must he in dose contact ivith the object to he de- Arrange-
molished, and all the slabs must he touching each other. n^ent of

Where the charge is a very long one, more than one detonator " ^^^S®-
should be used.

The charge must extend across the whole length of the object placing of
to be cut. charge.

Arrangements must be made to prevent sparks from the
fuze falling on it and so setting it alight instead of detonating it.

For calculation of charge, see Chapter XXI. Amount of

charge.

Gunpowder.

201. Gunpowder is not so suitable for hasty demolitions as Details,
guncotton. and the larger the grain of the gunpowder the less
suitable it is, owing to its slow burning.

Except the larger grained prism and moulded powders,
which are packed in cases, it is usually carried in barrels,
the powder being contained in a waterproof bag inside the
barrels.

Powder is usually fired by safety or instantaneous fuze. Ignition.

A gunpowder charge should be made up in as compact Making up
a form as possible, and if sandbags filled with earth are used t!iechargf.
to tamp it, the charge should be of the same shape as the sand
bags.

A service sandbag will hold about 40 lbs. of gunpowder,
which is about as much as a man can carry conveniently.
When a charge has to be placed under fire, and the amount is
greater than this, it should be divided amongst several bags,
as required, rather than put into one large one. In this case
only one bag need be fuzed.

* Eectifiers arc boxwood implements supplied for enlarging tlie per-
forations in guncotton primers so as to take the shanks of detonators.

(5289) V

82 CHAPTER XVI. — HASTY DEMOLITIONS.

Connet- A gunpowder charge should not, as a rule, be spread evenly
ing up along the whole breadth of the object to be destroyed, but
'"■■'^'* should be divided up into portions, which may generally be

ignition ^^ ^ distance apart of twice the thickness of the object. The

several portions must be fired simultaneously.

In the case of a stockade or fort gate, one concentrated

charge will make a breach wide enough to admit of easy

entrance.
Amount of For the amount of charges suitable, see Chapter XXI.
fharge.

Cordite.

Supply. 202. Cordite can be used instead of guncotton or dynamite.

It may be obtained from gun cartridges, and would only be

used where no other explosive is available.
Making up It must be detonated with a guncotton primer, and the
charge. cordite should be tied up in a tight bundle with the primer in

the centre.

The primer being connected up with No. 8 detonator and

fuze as described for guncotton.

Its successful detonation is rather uncertain.
Placing As with guncotton, the charge must be in close contact with

charge. the object to be demohshed.

The cordite must be covered up with fresh grass or leaves

to prevent the sparks from the fuze setting it alight, which

happens very easily.
Amount of As for guncotton, see table, Chapter XXI.
charge.

Dyxamite.

Supply. 203. D}Tianiite, where procurable, can be used instead of

guncotton.

For military purposes the only advantage that dynamite
has over guncotton is, that being plastic it is easier to fit into
narrow and irregular holes such as are used for blasting rock.

CHAPTER XVI. — HASTY DEMOLITIONS. 83

For demolishing masonry it is not so good as guncottom,.
as its action is even more local.

It cannot be used after exposure to wet, which separates General
the nitro- glycerine and makes it dangerous. properlies.

It freezes at 40° F., and remains frozen at higher tempera-
tures. Frozen dynamite can be distinguished by being
harder than unfrozen, by being more brittle than plastic, and
being of a slightly lighter colour.

Frozen dynamite should if possible be thawed before use.
It cannot be usad when frozen as it will not detonate readily,
though it will explode bv simple ignition.

IT MUST NOT BE THAWED NEAR A FIRE, but by
the warmth of warm water, in some apparatus like a common
glue pot, where the dynamite can be kept dry while surrounded
by warm water not hotter than the wrist can bear.

It is usually obtained in 2 oz. cartridges wrapped in parch- Supply,
ment paper.

It can be detonated by fuze and No. 8 detonator, or by Detona-
fuze and cap. tion.

No. 8 detonator is unnecessarily strong.

When cold weather is likely, dynamite should be buried a Storage.
foot or two underground.

Dynamite Charges.

204. If a No. 8 detonator be used, this is connected up with Connecb-
fuze, as described for guncotton, and the end inserted into one J^g ^^P
of the cartridges for about 2 inches and tied in. ^^'^^ ^

•1 • 11 -1 itj^ix means oi

If a commercial cap is used, the straight cut end oi the luze oietona-
having been gently inserted into the mouth of the cap till tion.
it touches the fulminate, the mouth of the cap is squeezed to
hold the fuze in place.

(5289) F 2

84 CHAPTER XVI.— HASTY DEMOLITIONS.

The cap, with the fuze attached, is then inserted into one of

the dynamite cartridges almost as far as its length, and tied

into position.
Arr.in2e- For a bore hole for blasting, or an auger hole in timber, as
inent of many cartridges as necessary are inserted, and each squeezed
cimrge. -^^ separately with a wooden rammer {see Fig. 7, PI. 68). Iron
Boreholes, must not be used to ram with, and the ramming should be

gently done.

The cartridge with detonator or cap for firing should be the

last,
ri icing For other charges the dynamite should be tied up in as

.thiirges. compact a parcel as possible, and placed tight against the

object, the means of detonation being in one cartridge.

All the cartridges of a charge must be in contact.

Hole for Holes for detonators or caps must be made with the rectifier

f-^P- or a piece of wood.

'lamping. The tamping of a bore hole may be sand, clay, or water,

but in the latter case the cap must be kept dry.
Ciiccldite. A new explosive called cheddite is coming into use; it has

about the same explosive effect as dynamite, and has the

advantage of not freezing at so high a temperature. It would

be useful in blasting work.
Use under For use under water dynamite and similar explosives should
uater. \jq ^ied in a waterproof bag {see PI. 68, Fig. 8) .

Means of Detonation and Ignition.
Detonators.

Dctoua- 205. There are two kinds of detonators in the service for

tors for detonating guncotton ; only one will be here described,
gunootton, y^^., that called " Detonator No. 8 for safety fuze " ; the

other, which requires electrical firing apparatus, being beyond

the scope of this manual.
Iso. 3 Fig. 1, PI. 68, gives a section of this detonator. It consists

dcionalor. ^f ^ brass tube painted red, the small end of which, A, contains

PlCLte f'8

HASTY DEMOLITIONS

Irq. J.

0Ti-Lrky^)lLCfj"7t

Ft^ 9.

■Jbi

^^•7'

s/ee. 4,05.

Sot/et^' fiae^s^J

TrkjfLe Commfn^rJ /fT C/tp

?oz d^y disc^

Tz^.S,

(pr'im.eif^j

.6.

^^ 7oz 7>rii

SFi^.S.

weiiera.GfiMtam.Lr!' urhoxenden.

Opposite pct^if S4

CHAPTER XVI. — HASTY DEMOLITIOMS 85

t"he detonating compound (fulminate of mercury) ; above this
is a wooden plug with a hole in it, through which passes a
piece of quickmatch. The upper end of the tube is empty,
for the insertion of the fuze, and is closed by a small paper cap.
These detonators are packed in tin sealed cylinders painted
red, which contain 25. A new pattern No. 8, with a short
shank, will shortly be introduced.

No. 8 detonator will detonate dry guncotton, but it will not
detonate wet guncotton or cordite without a primer. Both
safety and instantaneous fuze can be connected to it.

Where dynamite is obtained a smaller kind of detonator Com-
used in civil works will often be available and should be used in mei-ciai
preference to No 8 detonators as being more economical. *^''^'^^^
This is the " commercial cap," which is made of copper, and
contains less fulminate than the No. 8 service detonator, see
Fig. 9, PI. 68.

These caps vary slightly in size and strength. To detonate-
dynamite, trebles are used as a rule. The weaker sorts cannot
be counted on to detonate guncotton primers, but "sextuples"
are strong enough.

They can be connected up to safety or instantaneous fuze.

Detonators must be stored apart from explosives ; when Storage-
attack is likely they should be protected from bullets.

Fuzes.

206. The present pattern of safety fuze is known as " Safety, Safety
No. 9." i"2s-

This consists of a train of fine gunpowder enclosed in jute
yarn, covered with guttapercha and waterproof tape. It
is packed in tin cylinders containing 8, 24, or 50 fathoms.
It is coloured black.

Safety fuze will burn under water. Bnmin^

under
water.

86 CHAPTER XVT. — HASTY DEMOLITIONS.

Bate of For practical work the rate of burning can be taken as 3 to

burning. 4 feet per minute.

Old fuze. Old fuze should have its rate of burning tested before
being used. Fuze which has been more than six months or so
in a tropical climate should be very carefully examined.

Lighting It is difficult to light safety fuze with a match or flame. A
portfire or vesu\'ian (fusee) is best, but in the absence of such
means of ignition,, the head of a match inserted in the fuze and
lit by another match, forms a good method of lighting. A
glowing cigar, cigarette or pipe is also good for the purpose.

Instantaneous Fuze.

Instanta- 207. Consists of two strands of quick match enclosed in flax
neous and several layers of guttapercha and waterproof tape,

fuze. j^ burns at the rate of 30 yards a second, or practically in-

stantaneously ; it is packed in sealed tins holding 100 yards.
It is coloured orange.

It can be distinguished in the dark from safety fuze by
feeUng the open crossed thread snaking outside it.

Joining Fuzes.

Joining 208. In firing charges with instantaneous fuze, a piece of

fuses. safety fuze should be joined on for hghting, in order to allow

time for getting away, except in special cases where the instan-
taneous fuze used is long enough to admit of being ht from
a safe place.
Joining To join safety and instantaneous fuze, cut the instantaneous

safety and f^ze on the slant so as to expose the quickmatch for a short
instanta- igng^ji ^Iso the safetv fuze in the same wav, takino; care that

DCOU.S O ' • ^^ ? o

fuze. the composition is well laid open.

Join these two surfaces together and bind up tight. A small
'^' ■ piece of wood is useful as a splint, and if handy, a little powder
or quickmatch can be put between the two fuzes (Fig. 2, PL 68).
Joining To join two lengths of instantaneous fuze, slit the outer

^^° covering of each piece of instantaneous fuze at the end, it

if"? t ^^^ ^^^^ ^^ turned to expose the quickmatch ; the strands are
neous then twisted together, the outer covering made to overlap the

fuze. joint, and firmly fixed with twine.

en AFTER XVI. — HASTY DEMOLITIONS. 87

Joints in fuze can be made waterproof by wrapping them Water-
round tight with indiarubber tape smeared with indiarubber pf'^ofing
solution, which aro articles of K.E. equipment. Ordinary ■'^"^ ^'
tape and tallow would do for a short time against damp.

Simultaneous Charges.

209. Charges are best fired simultaneously by electricity. Simulta-
When this is not available, it may be done as shown in Fig. 3, ^^"^
PL 68, by using equal lengths of instantaneous fuze, " 6c," '°
which are ignited at " 6 " by a length of safety fuze, "a?>."

The joint at " b " can be made with a small bag or box
of gunpowder, into which the end of the piece of safety fuze
and the ends of the instantaneous fuze are led, the quick-
match in the latter being exposed.

Care must be taken that the lengths of instantaneous fuze
are equxil, irrespective of the distance from the powder box to the
charges.

Substitutes for Service Fuzes.

210. When service fuzes are not available, means of firmg
must be improvised.

" Mealed powder " (which is very fine), moistened, or ordinary Mealed
gunpowder ground into a fine paste with water between two powder,
pieces of wood, can be pressed into a tube and used instead
of safety fuze.

Tliis burns at the rate of 2 feet per minute, or slower, depend-
ing on the dampness of the powder.

Powder hose, made up by filling tubes of strong linen Powder
with fine powder, can be used instead of instantaneous fuze, ^^o^^-

The tubes can be from -J inch to 1 inch in diameter, made
from one strip of stuff ; they are loaded in lengths up to 20 feet
through a funnel. The lengths can afterwards be joined.

It burns at the rate of from 10 feet to 20 feet per second.

Precautions.

211. For amount of explosive required, see Chapter XXI. General
For cordite and dynamite use slightly more than is required ^^^^'

for guncotton.

CHAPTER XVI. — HASTY DEMOLITIONS.

Storage of
(letonators
iu cam}3.

Connect-
ing up
detona-
tors.

Connect-
ing up
caps. '

Protec-
tion to
detona-
tor for
lamping.

When possible, tamp all charges. If guncotton charges
are tamped, one-half the charges given in the table are sufficient.

For demohtions in the presence of the enemy, increase the
calculated charges by 50 per cent.

Detonators should be buried to prevent being exploded by
stray bullets.

When connecting up No. 8 detonators with fuze, the de-
tonating ends of the fuze should not be pointed at anybody.

When carried out under fire, take every precaution against
a possible failure ; detail spare men to carry the stores to
replace casualties, and see that every man with the party has
tl'^^ mean." of lighting the charge.

For large charges of all sorts which cannot easily be got at
after tamping, and for demolition work where certainty and
rapidity are essential, it is a good rule to insert two fuzes (and
detonators if required) in the charge in case one should prove^
faulty.

When pinching or bending the mouth of a detonator or cap
to grip the fuze, care should be taken not to squeeze the
detonating end.

When tamping a guncotton charge with earth, stones, &c.,,
the detonator should be protected from being knocked.

Make arrangements to prevent sparks from the fuze causing
premature explosion of gunpowder charges, or setting fire to
guncotton.

Brickwork and Masonry.
General. 212. For the demolition of brickwork or masonry with gun-
cotton, the charges worked out by the formulae in the table-
will sometimes be too small to allow the whole length of th&
breach to be cut, being covered with whole slabs touching each,
other. In such a case : —

(a) If guncotton is available, do not divide slabs, but add

extra slabs till the whole length to be cut is covered

by slabs touching each other.
(6) If plenty of guncotton is not available, cut some of

the slabs so as to make the charge stretch right across.

Smaller pieces than thirds of slabs should not be

used.

PlaU^ 69.

Ttq.3.

PREPARING CHARGES

Tx^.4-:

^^■o.

^o^vd&r

-4 14 'i^ ^

MB / 5^ no/ hag holds about 50 lbs of Gunpotvder.

We»l<riS/»l»*iJi. L'f UWW.Lon^OO.

Y^jo.^it^ pa^f^ s^.

CHAPTER XVI. — HASTY DEMOLITIONS. 89

213. Where there is a series of arches, as in a viaduct, the Brick anca

best result is got bv cutting the piers and so bringing down two masonry

arch
b rid "res.

arches for each charge, but in hasty demolitions this can only ^

be done when the piers are thin and high.

214. The best explosive to use for this purpose is guncotton. High and
The charge should be placed w^here the section of the pier is thin piers,
smallest, and if possible a groove should be cut in the pier to G"""-
place the charge in ; this reduces "T" and also to some extent co*^*^<^^'
tamps the charge. Otherwise the charge should be tied in a
continuous strip along a board, and this fixed on to the pier with

the guncotton next it (PL 70, Fig. 1, and PL 69, Figs. 1 and 2).

215. The piers cannot be satisfactorily demolished with Gun-
gunpowder in haste, as the speediest method of placmg the powder,
charge would take some time ; it would generally be better

to attack the arches.

The following is the quickest Avay of attacking piers : —
Divide the whole charge into two or three parts, and as the
chambers cannot be cut in the pier, place the charges in pits
dug in the' ground close alongside each pier. Tamp with earth
and fire simultaneously. If the piers are in water the above
cannot be done.

216. The amount of guncotton and gunpowder for cutting Short and
short and thick piers is prohibitive, and the arches should be thick
attacked. The best method of doing this is to place a charge P^^''^-

at eacJi " haunch " of the arch. This ensures a much larger gap
being made than if only one charge were placed at the " crown."

217. If guncotton be used, a trench must be dug down to the G-un-
back of the arch ring at each haunch. Then the slabs (tied to cotton,
a board if possible) should be laid all along the trench on the
back of the arch ring. If it is desired to economise the
explosive, tamping maybe used, but it is not essential (PL 70,

Fig. 4).

218. If gunpowder be employed, the charge for each haunch Gun-
should be divided into equal parts, which should be placed powder,
about twice the thickness of the arch-ring apart from each
other, the outside ones being placed twice the thickness of the
arch-ring from the side walls, to avoid the charges blowing

out through the side walls. A pit must be dug for each
portion of the charge down to the back of the arch, and tamping
is necessary equal to twice the thickness of the arch.

unaer
arch.

90 CHAPTER XVI. — HASTY DEMOLITIONS.

In all cases the charges at both haunches should be fired
simultaneously.

When there is not enough time to reach the haunches,
the crown {a) may be attacked in a similar way, but the result
is not so satisfactory (PI. 70, Fig. 4).
6iin- 219. Where time presses, small arches can be cut by gun-

cotton cotton at the crown without digging through the roadwav. The
charge to cut through the arch can be tied in a continuous
strip along a plank, and this hold up underneath the arch
by ropes from the parapet at the qtovhi, vdXh. the guncotton
next the arch. These ropes should be windlassed up tight
so as to ensure contact between the guncotton and the arch.
The plank should be supported or trussed to prevent sagging
in the middle.
Walls. 220. To demolish a wall by guncotton, a groove should be

cut, if possible, for the charge in the wall ; if not possible,
Gun- the charge should be laid against the wall. {See PL 70,

cotton. pi^g_ 2 and 3.)

Gun- With gunpowder the total charge should be di\dded up into

powder. parts, each part being placed from the next a distance equal
to twice the thickness of the wall. Earth tamping should
be used.

To bring down the top of a wall, the length of the breach
cut must be not less than the height of the wall.
Houses 221. For weakly-built houses, place a charge in the centre of

and huts. ^^^^ room, shutting all doors and windows. If possible, fire
charges simultaneously by electricity. The amount of
explosive required depends on the size of the rooms and the
nature of the walls. Mud huts up to 18 ft. square, with walls

2 feet thick at the bottom, have been destroyed by about
4 lbs. of guncotton placed inside the hut in one corner, all
openings being closed; 6 to 12 lbs. of guncotton will probably
destroy a four-roomed cottage. For strongly-built buildings
it mav be necessary to attack the walls.

Towers of 222. Towers such as those in the North- West Frontier of
stone and j^^^^^ ,^^^ usually 15 feet to 20 feet square in plan, with walls

3 feet or 4 feet thick, solid up to a height of 15 feet to 20 feet.
Gun- "Yi^Q walls consist of stone and mud. \^'ith layers of brushwood.
CO ton. rp^ blow down one of these, a tunnel should be made into the

centre of the tower under a layer of brushwood (which keeps

PlctJbe 70.

HASTY DEMOUTIONS.

J-t^.7.

^P^-3.

J^^.^,

SI 9 e. 8. 05.

WeilerA Graham, L»^ Li tho. London.
Opposifje pcuge 90.

CHAPTER XVI. — HASTY DEMOLITIONS. ' 91

the roof from falling in), and guncotton charges placed at
the ends of the tunnel, the whole being tamped.

223. Charge for a tower with a solid base of 15 feet side is Charges,
about 16 lbs.

Charge for a tower with a solid base of 25 feet side is about
24 lbs.

For hollow towers charges of 6 lbs. of guncotton placed inside
the tower at one corner, and in the centres of two adjacent
sides, fired simultaneously, will generally be effective.

Timber.

224. It is more economical to destroy baulks of timber by Tin^b^r
cutting them down or burning them than by explosives, which uprights,
would only be used when time presses.

225. Of explosives guncotton is the best, and is most G-un-
economically used when placed in auger holes bored horizon- ^'otton in
tally at the required height for cutting. For baulks up ^^^^^
to 18 inches diameter one auger hole will suffice, bored to

just beyond the centre, the centre of the charge being in
the centre of the timber (PI. 68, Fig. 4).

For larger baulks two or more holes will be needed, bored
alongside each other, the intervening portion of wood being
cut away.

The whole charge should consist of primers : 2-oz. primers
in a 2-inch auger hole, or 1-oz. primers in a It-inch auger hole,
earth or clay being used for tamping. The fuze may be hung
on a nail or splinter to take the weight off the detonator.

226. Dynamite can be used in a similar manner. It must Djnamite.
be carefully and gently rammed to fit the auger hole.

227. To save the wood rom being splintered, or where great ^^eck!ace
haste is necessary, the demolition can be done with a necklace of g""-
of guncotton primers ; but this method is very wasteful of ^°*^°"
explosive, and can only be used for small timbers, and is not 1^^^°^^"'
even certain then.

Sufficient primers, threaded on a string, to reach all round the
timber, each f rimer touching the next and the timber, are hung
on nails. The detonator may be inserted in one of these
or in an extra primer tied to one of the others.

Timber may also be blowm down by a charge of guncotton
in slabs. In this case a niche may be cut for it to decrease " T."

92 CHAPTER XVI. — HASTY DEMOLITIONS.

Timber may be made to fall in any required direction hy
getting a strain on it beforehand with a rope.
Timber or 228. The most convenient way to place a guncotton charge
timber and against a stockade, so as to ensure contact between the slabs,
^f , , is to tie them beforehand on to a board, and to carry this up
with the guncotton attached; a hole must be cut in the board
for the detonator and fuze (PL 69, Figs. 1 and 2).
Gun- The board is placed with the guncotton next the stockade,

cotton. j^jjjj ^^yQ pici^ets can be driven into the ground to keep it there,
or a couple of nails driven into the stockade, to which, the
charge may be hung.

The length of the board and the charge must equal the
breadth of the breech to be made.
Gun- 229. A gunpowder charge can be made up as follows (PI. G9,

powder. j'igg 3^ 4^ and 5) :—

Making up The powder should be placed in a well tarred sandbag, or

tlie charge, faihng that, in one sandbag inside a second one. About half

the powder is first poured into the bag, and then the safety

fuze, knotted round a stick to prevent its being pulled out, is

Connect- inserted, a piece of stout wire or a withe being also attached

ing up ^^ ^j^g stick, to help to support the fuze after it leaves the

means of mouth of the bag. The rest of the powder is then poured into

ignition, the bag. and the mouth is secured with spun yarn as shown, so

as to make it more easy to carry, a last seizing of the spun

yarn being made round the fuze so that any pull on it wiD

fall on the spun yarn and not on the fuze iteslf .

The fuze will almost invariably ignite the charge by burning
through its wrapping as soon as it reaches the powder. The
necessary lengths of fuze should therefore be measured from
outside the mouth of the bag.

Instantaneous fuze in addition to safety fuze should not be
used where there is only one charge, as it increases the liability
to missfire.
Placing 230. To place a bag against a gate or stockade, the precau-

tliechavgc. tions mentioned in Sec. 211 should be observed, and, in addition,,
the men carrying the tamping bags should be thoroughly
drilled as to how the charge and tamping is to be placed.
The man carrying the powder bag on his shoulder leads the
way, and placing the bag, fuze down- wind, and so that the fuze
does not curl up against the charge, against the stockade^

CHAPTER XVI. — HASTY DEMOLITIONS. 93

prepares to light. The other men, each carrying a bag in the
same way, successively drop them so as to place them as shown
in Fig. 5, PI. 69. The fuze is then lighted, and all get away as
quickly as possible.

For a gap 5 feet to 6 feet wide, a charge of 60 lbs. to 80 lbs.,
roughly tamped with sandbags, as shown in Fig. 5, PI. 69, will
suffice.

231. The gate of a fort may be treated as a very strong Fort gate,
stockade. As the thickness cannot usually be known, a good
margin in the amount of the charge should be allowed.

For guncotton 50 lbs. will usually be enough, either placed Gun-
on the ground or hung to the gate on a nail carried for the cottou.
purpose and driven in.

For gunpowder a charge of 200 lbs., tamped with sandbags, Gun-
should suffice. powder.

Railways.

232. On railways, the easiest parts to attack in hasty demoli- Bridges,
tions are the bridges.

233. Masonry arch bridges should be attacked as described Masonry
already. bridges.

234. Iron and steel bridges can be destroyed with small ex- iron and
penditure of explosive. steel

The girders maij be destroyed by placing charges of gun- bridges,
powder or guncotton beneath the ends at the supports ;"but Gun-
by far the quickest may is to actually cut the girders them- cotton,
selves with guncotton.

Nearly all girders consist of a top and a bottom " flange " or Girders.
" boom,'' cr^nnected by a " web,'' which may either consist
of continuous plating or of open cross bracing.

All girder bridges have at least two main girders which Usual
carry the flooring and go right across the span, and these main arrange-
girders alone need be attacked. "^^"'^ '^^

As a rule the best effect will be produced by cutting a girder bridges.
near a point of support, and this course will be economical p^g-^i^^ q£
of explosive, as the flanges are usually slighter at the ends than charge,
at the centre. In the case of a girder continuous over several
spans, the point selected should be in the first or last span, at
the end awav from the shore.

94 CHAPTER XVI — HASTY DEMOLITIONS.

If there is any doubt about the efiect of one charge, the girder
should be cut at each end of a span.

In the case of girders buiit on the arch principal, two charges
should always be employed, with the object of blowing away
a segment of the arch. (PL 71, Fig. 5.) In girders with an
open web, the top and bottom flanges should be cut. In
girders with a plate web (unless this is very thin relatively to the
flanges) both flanges and web should be cut. When there is
a lack of explosive, the bottom flange is the most important to
cut.
Charge?. The arrangement of the charges will depend on the section
of the girder ; to simplify the firing arrangements, they should
be divided up as little as possible. The charge for the top
flange will generally be placed on the top, and that for the
bottom flange underneath. In each case they will be most
easily fixed if fastened to a board. The charge for the web,
if any, should be tied to a board, the ends of which can be wedged
up between the flanges.

Where there is a choice between masonry and iron girder
bridges, the girder bridge ought, as a rule, to be attacked, as
the demolition of the girder bridge will be much quicker,
and will save guncotton {see PI. 71).
RmIs. 235. Two-thirds of a lb. of guncotton is necessary to destroy

heavy rails. Two-thirds of a lb, is most conveniently got by
cutting a l|-lb. slab into thirds, as this size fits into the web
of the ordinary sized rail.

Six 2-oz. primers (with the detonator in one of them) will
also do, but is not so convenient to fix. Where the charge
can be wedged between the rails at points or a crossing, a
less charge will do this, as this tamps it.

On the straight line the slab should be tied tight into the
web of a rail close to a chair on the same side as the key.
Lead strips are provided for fixing the slabs to the rail, but
string suffices (PL 72, Figs, 2 and 3), or the key may be
removed and the charge put in its place. In the hasty
demolition of a railway fine care must be taken that the break
J6 sufficiently broad, or the rails displaced, so as to ensure the
stopping of traffic.

An effective way of damaging a railway line is by firing

I>lat^ IL

GIRDER BRIDGES

VrT\ I I I

Wedged

J^osztioTLr o/" CTiccnaes 21X,

ope

Clip

JfooderL

riifu

GirdLer' -itztA plate.

-^^.

•pT'znczpZe- sTvcnvrLhy ciott&d^

Fi^.^.

Ti^6

CTtaarffe-TrL

FToTLof ytrdeT^

S/8€. 8 <tS.

Opposite pcLge 94,

CHAPTER XVI. — HASTY DEMOLITIONS. 95

charges under the rail joints. This will bulge the rails
vertically and make traffic impossible. This method however
requires a large amount of explosive. If alternate joints are
attacked every rail mil be damaged.

236. Blowing in tunnels is a very good way of stopping traffic, Tunnels,
but to be effective requires a large quantity of explosive.

Gunpowder is best for this. Gun-

The points attacked should be some distance w^ithin the powder. ,

tunnels, and it is better to blow dowm one long tunnel in several
places than several tunnels in one place only.

The crown or the haunches should be attacked as in cutting I

arches, and the lining should be brought dowm for some distance
along the length of the tunnel.

In hard soil it will not do much harm to cut the lining only,
as very little of the soil may fall.

The charges should be placed as far back from the interior Placing
surface of the arch as time and explosive available will allow, charges,
and twdce as far from each other as from the surface. ^

For calculating the charge, T should be taken as the total Amount of J

distance from the surface of the lining to the charge. ^ arges. ig

The charges should be in chambers branching off the gallery ^^

dug in from the surface of the tunnel.

Instructions for the Destruction of Guns.

237. (1.) A shell having been loaded in the ordinary w^ay, the Field and
guncotton charge necessary for the destruction of the gun ^i^gi? guns
should be packed in behind it so as to be in close contact wdth
the shell and with the sides of the chamber. After the insertion
of the primer, sods, earth, paper or other material that may be
at hand should be used to keep the guncotton in position.

(2.) The breech block should then be swung to as far as
possible, just allowing room for the safety fuze or electric leads
for igniting the charge.

(3.) The charges required for guns from 3-inch to (3-inch
caUbre are given by the following rule : —

CO CHAPTER XVII.— HASTY DEMOLITIONS.

*' For a 3-inch gun use 2 lbs., and double the charrrc for

every inch increase in calibre, e.g., for a 4-inch gun

use 4 lbs., and for a o-inch, 8 lbs."

(4.) A shell is not absolutely necessary for destroying a gun

l)v the above method, but, if available, its use increases the

effect.

(For B.L. guns, if a crowbar or heavy hammer is available,
much damage can be done by opening the breechblock
and smashing the block and screw threads in the breech, thus
saving explosive.)

Heavy M.L. guns can be demolished by placin,^ 4 lbs. of
guncotton at the bottom of the bore and tamping with sand or
water.

Demoli-
tion of
rail WOTS.

ijlation?,
buildingsi,

CHAPTER XVII.— HASTY DEMOLITION OF RAILWAYS
AND TELEGRAPHS WITHOUT EXPLOSIVES.

RaUways.

238. When a demolition is contemplated, all unnecessary
rolling stock should first be withdrawn. Simultaneously with
this, all reserves of railway plant and the most important
technical tools should be removed from the station, as well
as all individuals entrusted with the working of the railway ;
and the signals, first the electric and then the visual, should be
destroyed. The permanent way should be attacked, and either
destroyed or removed altogether, the most important item
being the destruction of as many points and crossings as
possible ; and the engineering works, such as the bridges,
tunnels, embankments, and cuttings, would also be important
items in the demolition if the abandoned line could be of use to
the enemy alone.

239. Buildings not being indispensable to the traffic, are
seldom worth destroying.

The different workshop fittings should be taken away alto-
gether, telegraphic appt'-ratus and batteries removed and
handed over to the Director of Telegraphs, and stationery
engines made unserviceable by taking out the piston, &c.

PlaX^ 72

HASTY DEMOLITIONS

^ <^.

Fi^.S.

fdse.6 . OS.

WellerAGrahaw.LW Litha Undort.

i).

CHAPTER XVII. — HASTY DEMOLITIONS. 97

The water supply of a line should invariably be attacked, Water
and the more complete the destruction of tanks and pumps supply.
the better.

240. The rolHng stock, if it cannot be removed to the rear, Rolling
may be rendered unserviceable by burning ; or trains may stock. "
be run against each other at full speed on the same line, or

they may be run over an embankment by turning a rail.

Locomotives may be rendered useless, but still repairable,
by taking oft the inj ector, or the connecting rods on each side
of the engine, or the piston or safety valve.

In carriages the springs may be removed so as to let the
body of the carriage fall on the wheels and axles, or the axles
themselves may be cut through by guncotton.

241. The method in which the permanent way is attacked Perma-
must depend greatly on the extent of damage desired, the time ^^ent way.
at disposal of the demohshing party, and the strength of that

party.

<:\ simple method, when explosives are not used, is to remove
portions of the hue at intervals, especially at curves, remove
switches, &c., and carry them away. To remove the rails,
unscrew the fish-plate nuts w-ith a spanner, if available, if not,
they may generally be broken ofi by hammering. The enemy
will find considerable difficulty in fitting in rails of the right
length in the demohshed portions, but if this method is adopted
on a double hne, at least one line of rails must be entirely
removed, and the other partially so, otherwise an adversarv
might renounce the advantages of a double Hue for a time, and
employ the material from one line of way to complete the
partially destroyed one.

242. A second method, used where many men are available,
and where the time is short, and the plant not required elsewhere,
is to attack the Une at several point at once, tear up the per-
manent way and render it useless on the spot.

Labourers are employed in preparing sleepers in piles for burn-
ing, placing rails upon them, and then twisting them. If the rails
are only bentthey can bebent back and used again, but if twisted
they must be sent to regular workshops to be re-rolled before
they can be utihsed. The chairs should be broken by a sledge

(5289) G

98 CHAPTER XVII. — HASTY DEMOLITIONS.

hammer. A variety ol this style of demolition is to lift up and
turn over whole portions of the railway, together with the
attached sleepers. This method is specially useful on high
embankments. The men are formed along a rail in single rank,
outside of it and facing inwards, the rails at both flanks are dis-
connected and at a signal they seize the rail, lift it up ^vith the
sleepers attached, and turn it over. Of course the ballast
must be previously removed. Teams of horses or oxen can be
hooked on to the rails and used in Uke manner.

243. Another method is to di\'ide the destropng party into
squads of ten men each, and to equip each party with two iron
hooks (Fig. 5, PI. 72), two axes, and two ropes, each six yards
long and two levers. The irons are then fixed as shown. The
ropes attached to the ends of the levers are hauled on, the rails
twisted and the chairs destroyed, one end of the rail being
pre\4ously disconnected. Each rail requires about five
minutes' work, so that in one hour a squad can destroy twelve
lengths of rail.

244. A fourth method of demolition is to take up the perma-
nent way and remove it bodily in wagons. Where there is a
double fine, the first line is removed by packing it into the
wagons which are alongside on the other line ; but the second
line has to be packed into wagons which have been run up close
to the end of the second line itself. This is the most satisfactory
of all styles of demolition, but requires much time, and careful
arrangement of the necessarily large working parties.

Tdegraj)hs.

Demoli- 245. The amount of damage that can be done in a short time

tion of ^Q a line of telegraph depends chiefly on the number of separate
oralis wires running parallel to each other on the same poles in the
° * case of an aerial line, or the number of separate cables con-
tained in the same set of pipes in a subterranean line. These
forms are by far the most likely to be encountered on service.
The case of a subaqueous line, which may sometimes be met
with, will be discussed later.

246. It is assumed that the line to be destroyed lies in a
country occupied by the enemy, to which access has been

CHAPTER XVII. — HASTY DEMOLITIONS. 99

obtained for a short time by a raid ; since if any part of the line

lay in a part of a country from which the enemy had been

expelled it would be of course easy either to disconnect the .

wires and appropriate them, or, leaving the lines intact, to "3

interpose instruments, and thereby read any messages sent by *

the enemy.

247. The poles can be readily cut or blown down, the easiest Destruc-
and safest poles to attack being those that have stays. tion of

A rope should first be fixed to the top of the pole or thrown ^^^'^^^ '^'^^•
over the wires in order to put on a strain tending to overthrow
the pole.

The pole should then be partly cut through at about i feet
from the ground. All hands should then commence to strain
on the rope, except one man, w^ho should cut the stay through
with a file or pliers. The men on the rope must be sufficiently
far from the pole to be well clear of the wires when they fall.

The destructive effect will be increased by previously
cutting partly through the adjacent poles on each side, and,
if several adjacent poles are also stayed, cutting their stay at
the same time.

Cast iron poles can easily be broken with a sledge hammer.

Having brought down as much as possible of the line in this
way, the wires should be cut at each end as far as can be reached,
and twisted up so as to be rendered useless. The insulators
should also be broken.

Any damage of this sort, however, can be quickly repaired by
the enemy using cable, and even the complete restoration of
poles and wires w411 not take very long to accomplish.

248. Probably an equal amount of delay could be occasioned Faults,
with less trouble by skilfully placing what are known as

" faults " on the Une.

Faults consist of " disconnections," "leaks," and "contacts."

" Disconnections " are partial or complete breaks in the
continuity of the conductor.

" Leaks " are partial or complete connections of the conductor
to earth. A complete connection is known as " dead earth."

" Contacts" are formed by one wire touching another or being
put in connection with it by some conductor. They are very
troublesome faults, since they affect two Hues, and cannot be
(5289) G 2

100

CHAPTER XVII. — HASTY DEMOLITIONS.

Durcage
done to an
office.

Destruc-
tion of
subter-
ranean
line.

Destruc-
tion of
subaque-
ous line.

overcome, as other partial faults can be, by increasing the
battery power.

All artificial faults, however, to be successful as causes of
delay require to be skilfully made, and the description of the
methods of making them is too technical to be suitable for
inclusion in this book.

249. If possession can be obtained of an office, wires can be
discomiected. Any papers connected with the working of the
line and, if possible, the instruments, should be sent to the
officer in charge of the field telegraphs.

Records of messages should be sent at once to the Head-
quarters.

250. A subterranean line is naturally more difficult to
discover than an aerial one ; for this reason among others they
are now extensively emploved in countries liable to invasion.
In England they are rarely met with except in large towns,
where overhead wires are dangerous.

The existence of such a line being known or suspected,
marks should be searched for at equal distances apart, indicating
the position of test boxes.

These marks are usually about 100 yards apart, and generally
consist of blocks of wood or stone numbered in succession.
They would very probably, however, have been removed by
the enemy.

If not to be found where the line is known to exist, a cross-
trench should be dug at right angles to the probable direction
of the fine, about 2 feet deep, and in this way the pipes may be
discovered. These can then be dug up as far as possible, and
bent or otherwise destroyed if means are available, the wire
being pulled out and cut to pieces.

If possible the trench should be carefully filled in and all
traces removed.

251. A subaqueous line is rarely employed except for
crossing seas or big rivers, but in time of war they may be
laid along the course of the rivers to connect towns on their
banks, as was done at Paris in the Franco- German war.

To destroy such a line it should be grappled for with a
grapnel, and when caught as large a piece as possible cut
out of it ; the piece should then be cut into smaller pieces and
thrown into deep water.

PART II.

CHAPTER XVIII.— STRENaTH OF MATERIALS
AND BUOYANCY.

Cordage.

252. The word " rope " is now officially u?3d to denote steel Kopes and
or iron wire rope, while hemp and fibre ropes are termed cordage.

" cordage." Colloquially " rope " is still used to denote
both classes.

The size of a rope is denoted by its circumference in inches,
and its length is given in fathoms. (A fathom is 6 feet.) Cord-
age is usually issued in coils of 113 fathoms, and steel wire
ropes in coils of 100 fathoms.

253. The breaking strain of ordinary sound cordage is obtained Strength

Q2 of cordage.

with fair accuracy from the formula 17 tons, where C is the

circumference in inches.

For field purposes C- cwts. has been laid down as the safe
working load for all cordage, but this may be increased, for
good cordage in good condition, to a maximum of 2C- c^vts.

254. The strength of wire varies greatly : as a very rough Strength
rule it may be taken that the breaking weight in pounds of wire,
equals three times the weight per mile in pounds. This rule

holds good for iron and hard drawn copper wire, while steel

wire may be taken as about twice as strong as iron wire.

The breaking strain in tons of iron wire rope is about equal Strength

to the square of the circumference in inches. Steel wire rope of wire

rope.

102

CHAPTER XVIII. — STRENGTH OF MATERIALS, ETC.

StrengUi
of chain.

is from 2 to 2J times as strong as iron wire rope. Wije rope
can be worked, for field service, up to half its breaking strain.

255. The following table gives the strength and weight of
ordinary crane chain, obtained chiefly by experiment (ordinary
commercial iron chain is not verv reliable) : —

256. The strength of a lashing may be taken as 4 of the
number of returns from the object lashed, e.g., a square
lashing with four turns has a holding power of i x 16 x
strength of rope ; in the case of a hook lashed to a spar with
four turns it is 4 x 8 x strength of rope.

When using wire in lashings, multiply by | instead of 4.

Timbers of Bridges.
Sfcrengtli 257. The following are the maximum weights, which are
of bridges, brought on by the passage of troops in marching order, per
lineal foot of bridge : —

Infantry, in file, crowded at a check, 2J cwts.

„ in fours ,, „ 5 ,,

Cavalry, in single file, crowded at a check, If cwts.
,, in half-sections ,, ,, 3i ,,

258. Maximum weight brought on a bridge by howitzers,
guns of position, &c. : —

5-inch B.L. howitzer and E.A. ammunition
wagons, Mark II with limber. Maximum
concentrated weight in one bay = 30 cwts.

4*7 -inch Q.F. guns of position wdth limber, on
travelling carriage. Maximum distributed
weight =85 „

CHAPTER XVIII. — STRENGTH OF MATERIALS, ETC. 103

259. A bridge that will carry infantry in fours crowded at a
check will carry any of the field guns and m.ost of the ordinary
wagons that accompany an army in the field.

260. A good rough formula for calculating the necessary sizes Formula
for road bearers and transoms is given below. The formula ^^^ ^ect-
includes a factor of U for live load, and gives a factor of ^^S^^^'*
safety of 3 ; it also allows for the weight of superstructure.

Unselected rectangular beams —

W=:^^xK {A)

Where W ■=■ actual distributed weight in cwts. (superstructure
not to be included).
h = breadth of beam in inches.
d — depth of beam in inches.
L = length of span in feet.
K = a variable quantity for different timbers (see below).

261. Uuselected round spars — Formula

Vr=^x^:xZ iB) i-T"'

The S3mibols being the same as for formula (.4), h and d
being- here equal, and round spars being- only about -5^0 as
strong- as square beams of^ the same depth.

262. For larch and cedar .. .. .. K=l Yaluea

„ Baltic fir K = l oiK.

„ American yellow pine . , . . A^ = f

„ beech and English oak . . . . A" = -^

In the above formula, W is the distributed weighty such as
that of troops, on any span.

263. If it is wished to use these formulae for a concentrated Concen-
weight, such as a gun, the actual weight on the gun wheels irated
must be multiplied by two to reduce it to the equivalent ^°^^^-
distributed load, when it can be substituted for W. When,

as in the case of a transom, there are concentrated loads at Transoms,
more than four points along the span, it will be sufficient to
take the total as being distributed.

264. With several baulks under a roadway, the two outer Baulks,
ones can be assumed as taking only half as much of the weight

as the inner ones.

104 CHAPTER XVIII. — STRENGTH OF MATERIALS, ETC.

the outer baulks each bear ^

Arrange-
menrs of
baulks.

Formula
for can-
tilever
bridge.

total
(In calcu-

Thus, with five baulks
weight, the inner baulks each bear J total weight
lating, the greater weight must be worked to.)

Rectangular beams are stronger on edge than on the flat,
and should be always used on edge.

265. In calculating the strength of a tapering spar when
used as a baulk, d is to be taken at the centre of the spar.

Experiment has proved that such baulks, when supported
at both ends and overloaded, will break in the centre, and
not at the small end.

Knowing h, d and L, from formula (A) or (B) we can find
TT^, the safe distributed load, for these data. Knowing \]\
and choosing L, a convenient length, we can find b and d^
the necessary section of the beam.

266. A rough formula for strength of cantilevers is as
follows : —

W = ^ --r- X K for square timbers.

W= the total live load which can be brought to bear

on the end of the cantilever in cwts.
L = the length of the cantilever in feet.
h = breadth 1 - • i
,i = depth I'^-n^l^e^- ■

/C = a variable quantity according to the tree for
values, see Sec. 2G2.

Formula
J or round
spars.

Weiglit of
•water.

For round spars : —

X K,

These formultB .c^ive an allow^ance for superstructure an(
factor of safety of 3.

267. Useful facts-
One cubic foot of water = GJ gallons;

One gallon weighs 10 lbs.

Buoyancy.

Buoyancy 268. In using closed vessels like casks for floating piers, the
of casks, gafe buoyancy for bridging purposes may be taken at y% the
actual buoyancy.

CHAPTER XVIII. — STRENGTH OF MATERIALS, ETC. 105

269. The buoyancy of closed vessels can be determined Closed
by the following methods : — vessels.

(a) When the contents are known —

Multiply the contents, in gallons, by 10, and take -^^ of
this, which will give safe buoyancy in pounds.

(6) For casks, when the contents are not known —

A cfval buoA'ancy = oC^L — AV lbs.
Safe buoyancy = yV {5C-L - W} lbs.

Where C is the circumference of the cask, in feet, halfway
between the bung and the extreme end ; L is the extreme
length, exclusive of projections along the curve, in feet ;
W is the weight of the barrels in pounds.

Collins*
rule.

270. The following are the dimensions, weight and buoyancy Table of
of certain casks : — casks.

§ •

Name of cask.

■&2

5 '**

5>%

ins.

ft.

lbs.

Heager

170

38-5

4-52

9-33

252

1,736

butt

108

33-3

3-97

8-09

174

1,125

puncheon

30-7

3-20

7-57

140

773

hogshead

28*6

2-76

7-05

119

.'i67

barrel

25-3

2-42

6-23

382

half hogshead

22*7

2-12

5-61

269

kilderkin

20-3

1-81

5-02

185

small cask

18-3

1-76

4-49

146

'^ l „

13-8

1 -37

3-40

I'owder f whole barrel

barrels \ quarter ,,

IT -5

1-58

4-26

28-5

115

—

1-17

2 '93

8-5

fton

Commissariat i 5 ton

—

3-2

9-96

1,477

—

3-2

8*69

1,134

vats 1 —ton

—

3-3

7-75

903

Ls-lon

2-5

6-61

499

Water cask

—

106 CHAPTER XVIII. — STRENGTH OF MATERIALS, ETC.

Buoyancy 271. The buoyancy of a log can be obtained by multiplying
^ ^^ ^^' its cubic content by the difference between its weight per
cubic foot and that of a cubic foot of water, viz., 62| lbs.

The actual flotation then of the log given below, if it were
pine, would be : —

95 X (62J - 40)
or 95 X 22^"

= 2,137i lbs.

As, however, timber absorbs a great deal of water, only | of
the above can be safely relied upon.

This available buoyancy will then be —
I X 2J37| = 1,781 lbs.

272. The contents in cubic feet of an unsquared log of timber
can be found by the following rule : —

^ (D- + Dd + d-).

Where L = length of log- in feet,
D, d = diameter at ends.

Thus, if the log- is 3 feet and 2 feet in diameter at the ends
and 20 feet Ion or —

Bridges of
rafts of
timber.

the cubic contents =

20
95 c.f.

W^eightof 273. The follow

ving are approximately the w

imber. foot of different kinds of timber :—

Ash, English

.. 46 lbs. Pine ..

Beech . .

.. 43 „ Poplar

Chestnut

.. 41 „ Sycamore

Elm

., 37 ,, Teak, Indian

Fir

.. 33 ,. „ African

Larch . .

.. 33 „ Yew ..

Maple . .

.. 32 „ Walnut

Oak, English

. . 57 „ Blue Gum

Willow . . . . 25 lbs.

40 lbs.

36
51
61
41
38
63

J'late 73.

Opposi te. jjcLtye 70.

107

CHAPTER XIX.— BLOCKS AND TACKLES— USE OF

SPARS.

274. Blocks are used for the purpose of changing the direction Blocks
of ropes or of gaining power. and

They are called single, double, treble, &c., according to the tac'des.
number of sheaves, which are of metal or hard wood, and
revolve on the pin, which should be kept well lubricated.

Snatch blocks, Fig. 1, PI. 73, are single blocks with an
opening in the shell and strap on one side, to admit a rope
without passing its end through.

The rope with which tackles are rove is called a fall. To
overhaul is to separate the blocks. To round in is to bring them
closer together. When brought together the blocks are said
to be chock.

275. A tackle is rove by two men, back to back, 6 feet apart ; KecTing.
the blocks should be on their sides between the men's feet,
hooks to their fronts, and the coil of rope to the right of the
block at which there are to be the greater number of returns.
Beginning with the lowest sheaf of this block, the end of the

fall which is to be the standing end is passed successively
through the sheaves from right to left and then made fast.

276. In using tackle great care must be taken to prevent the Pre.
tackle from twisting. The best method is to place a handspike cautions
between the returns, close to the movable block, with a rope ^^^^■^
to each end, by means of which it can be steadied. New rope

must be uncoiled and stretched before using it as a " fall."

Crane chain, when used as a fall, should be thoroughly Crane
soaked in oil. cliain.

277. Various tackles are sho\sTi in PI. 73. The power Power.
necessary to raise a weight W is W -f- number of returns at the
movable block -f- about 10 per cent, per sheaf for friction.

278. The fall, in lifting heavy weights, can rarely be worked Machines,
by hand, but has to be " led " to either a capstan or winch,

by which power is gained and a steady pull ensured.

108 CHAPTER XIX. — BLOCKS AND TACKLES, ETC.

Carrying 279. In carrying spars, the party should be equally divided
spars. on either side of the spars, facing it, and sized from one end.
The spar should then be lifted, in two motions, on to the inner
shoulders, the party facing one way. In lowering a spar, the
party should slowly face inw^ards, and lower the butt end
first to the ground, and afterwards the tip.

Derricks. 280. A derrick (Fig. G, PI. 48) is a single spar set up with
four guys, secured with clove hitches. A tackle is lashed to
the head, and the derrick can be used for raising and swinging
a w^eight into any position within its reach, which is about
one-fifth of its height. The anchorages for the guys should be
at a distance from the foot of the derrick equal to twice its
height. The foot should be let into a hole in the ground to
prevent its slipping.

In Fig. 6, PI. 74, a derrick is shown in the act of raising a
pair of sheers.

Fig. 8 show^s a swinging derrick.

Sheers. 281. Sheers (Fig. 4) require only two guys— a " fore " and

" back " guy. They should be fastened to the legs above the
crutch by clove hitches, the back guy to the fore spar, and
vice versa, so that their action may tend to draw^ the spars
closer together and not strain the lashing. The minimum
distance of the anchorages should be double the height.
The upper block of the tackle is hooked to a sling of rope or
chain passed over the crutch. Sheers can, as a rule, be used
for heavier weights than derricks, but can only move them in a
vertical plane passing between the legs. The feet of sheers
must be secured or let into holes in the ground. The distance
apart of the legs should not be more than one-third the length
of the leg up to the crutch, and the sheers not to be heeled
over more than one-fifth of their height.
Sheer 282. The legs of the sheers are laid side by side on a skid, and

lashing. j-ept 2 inches apart by a wedge. The lashing is commenced
with a clove hitch on one spar, carried six or more times
upwards round both spars without riding, then tw^o Trapping
turns, and finished off w^ith two half hitches round the other
spar. (Figs. 1 and 2, PI. 74.)

I*lcOte '74

Fi^.L

USE OF SPARS

jtiq.Z.

Fry. 3

STveei^s

ybte. . JBiflFiff. S. fyctf^pTiriff turns
ar^ cT/oMed' so us to s?to\^

WellerAGratwm.LH Litho.LofxJon.

CHAPTER XX. — FRAME BRIDGES, ETC. 100

283. Gyns, Fig. 5, require no guys, and are good for a Gyns.
vertical lift, such as dismounting gans.

The three legs of the gyn are placed as shown in Fig. 3,
resting on a skid, and 2 inches apart. The lashing is com-
menced with a clove hitch on an outside spar, and carried
upwards over and under loosely and without riding six times.
Two frapping turns are taken in each interval, and the whole
finished off with two half hitches round one of the spars.

Iron chain is better than rope for these lashings, as it admits
of fewer turns, which allows the legs to be more easily opened.

284. In using tackles with sheers, gyns, or derricks, the Leading
running end of the fall should always be led through a " leading blocks,
block," lashed, as a rule, to one of the spars a few feet above the
ground ; a snatch block is most convenient for the purpose.

(Fig. 7, PI. 74.)

CHAPTEK XX. — CANTILEVER BRIDGES, FRAME
BRIDGES, FRAMED TRESTLES, SUSPENSION
BRIDGES, AND CASK PIERS.

285. Pis. 75 and 7G show various types of cantilever Cantilever
bridges as used in Northern India. bridges.

From the smallest to Ihe largest span the method of con-
struction is practically identical. A site is chosen where a
large rock or rocks rise out of the stream or a pier is con-
structed of dry stone work and wooden bindings. On the
top of tliese are laid a number of stout beams, ««, projecting
over the stream, with the projecting end somewhat higher
than the shore-ends. The number of beams, their length and
amount of projection depend on the span. The shore-ends of
each row of cantilevers should be covered with planks or like
material. Stones are then packed round these ends, and the
v/hole weighted down. It is also desirable to lash the top
iayers to the bottom ones as shown in Figs. 5 and G.

CHAPTER XX. — FRAME BRIDGES, ETC.

Frame
bridges.

Single-
lock
bridge.

Double-
lock
br.due.

Supposin^!^ that the central span is too lar.i^e for available
timbers, then more rows of cantilevers are placed on the first
row aa, two more transoms tt are placed near the projecting"
ends and the roadbearers rr are placed in position. There are
<ienerally more cantilevers in the bottom row than in the row
above and so on. Figs. 5 and G.

The step from top row of cantilevers to top of central road-
bearers can be avoided by lashing the top transom underneath
the ends of the top rov/ of cantilevers instead of placing- it on
the top, or an extra row of roadbearers may be added above
the top row of cantilevers. In the case of a long bridge a
few wire ties are a great improvement, as they stiffen the
bridge greatl3\ Fig. 7.

286. The following are simple types of frame bridges : —

{a) Single Lock. — Supporting one central transom, and
sufficing for a span up to 30 feet.

(6) DouUe Lock. — Furnishing two transoms, span up to
45 feet.

They are not so generally useful as trestle bridges.

The span of a frame bridge is the horizontal distance
between the footings of the frames, and is independent of any
increase of span due to sloping banks or bays of trestles.

287. A single-lock bridge (Pi. 77) consists of two frames
locking together ; one frame must therefore be narrower than
the other.

288. A double-lock bridge (PI. 77) consists of two frames
held apart by distance pieces. The frames must therefore be
the same width.

The frames are nearly identical with two-leg-ged trestles
{Fig. 2. PL 50). but the slope of the legs is not so great, ^~-
generally suflricing, and the transom and ledger are lashed on
on opposite sides of the legs, transom on the shore side so as
to bear on the legs, ledger on the outer side so as not to
interfere with the footings. Before lowering the frames into
their places footings must be prepared, holdfasts driven, fore
and back guys attached to the top of each leg, and foot ropes
attached to tach leg below the ledger. The frames are then

J^Utte^ 75.

CANTILEVER BRIDGES

J^i^.7

JSZei/atioTh

S/g6 Bc$.

W«lt«riGreh«m.L'^ lifho Lonoon

To fcLcepa^B JfO.

'Pl^fte 76

To faWjnv plate 75

Flat^> n.

LOCK BRIDGES.

a. road boarers,

b.fork tranaoai.

c. frame transom.

d. shore transom.
e„ legs.
f. djAgonal bra(»3

SINGLE LOCK.

g. ledger.

"• footings.

i. anchorage for

f potropes .
J. chesses,
k. ribands.

a. read bearer.

b. road transom.

c. frame transom.

d. shore transom,
legs.

f . diagonal braces

g. ledger.
n. footings,
i. footropes^
j, chesses.

ribands .

distance pieces

Note J Pootrofes are removecT after franies are locked.

■iiec 9 05

WdlerAGraham. Lri* UHio.London.
To f'olZcw Ptoute 76.

CHAPTER XX. — FRAME BRIDGES, ETC. Ill

lowered, and if a single-lock bridge, locked ; if a double-lock

bridge, held back by the guys a little higher than their

ultimate position. A single-lock bridg'e is then completed

with the usual roadway : for a double-lock bridge two ^

distance pieces must be placed across the ends of the frame

transoms, as shown in the diagram and the road-bearing

transoms lashed across, as shown. The back gu^'s can now

be eased, and the bridge allowed to lock. The roadway is

completed as usual.

In order that the parts of frame bridges may fit together,
considerable accuracy is necessary in taking the measure-
ments and marking the positions for the lashings. To this
end a section of the gap and proposed bridge should be
marked out on the ground, allowing for camber. The spars
for the legs must now be laid on this section in the exact
positions they will occupy when in bridge, and marked to show
proper positions for lashing on ledgers and transoms.

289. The following approximate dimensions of timbers for Dimen-
single and double lock bridges are necessary for carrying ^1*^"^ °^
infantry in fours crowded : —

Legs . . 7 inches at tip.

Frame transoms, mean diameter . . 6 inches.
Distance pieces ,, ,, .. 11 inches.

Other spars as for trestle bridges.

290. Plates 78, 79 and 80 show examples of heavy trestles Framed
made of timbers framed together and fastened by iron dogs, t^^^^^^^*
spikes, bolts ^ etc. They are specially useful for hasty railway
bridges (see also Chap. XXIII) and for road bridges where
heavy traffic is expected. Skilled labour is required for
their construction.

These trestles usually consist of groundsills, capsills, uprights,
struts, and diagonal braces and stringers connecting the trestles
in the line of the bridge.

The uprights should be as far as possible arranged under the
road-bearers, so as to support the weight directly. When
they can be got of sufficient length, it is best to make the trestles
in one tier only, however high the bridge, taking care of course
that they are properly braced both ways to prevent buckling
(PI. 78, Fig. 1 and PI. 79, Fig. 1).

When the material is not long enough, the trestles must be

112

CHAPTER XX. — FRAME BRIDGES, ETC.

Struts.

Bra(

Corbel.

Pasten-
inss.

made in two or more tiers. In this case the upper tiers must
not be made too heavy, or they will be very difficult to hoist
into position. The groundsills of the lower tier must be strong
enough to support and distribute the weight of the uprights.
Where the soil is firm and can be levelled to an even bed, no
other foundation than the groundsill is necessary ; where the
soil is soft a low crib pier may be made to distribute the weight.
The adjoining capsill and groundsill, where one trestle rests
on another, need not be very strong. A 3-inch plank will suffice
for each, and may be spiked to the uprights. In this case
the uprights may be fixed in position with cleats, and dogged
to each other (PL 78, Fig. 2).

291. The inclination of the struts depend to some extent
on the height, width and length of the bridge. They are not
essential for wide bridges of no great height.

Struts for railway bridges must have a greater inclination
than for ordinary bridges to provide for wind pressure on the
side of the train tending to overturn the whole structure.
This is especially the case when the bridge is high and long.

292. For the arrangement of the diagonal bracing, see
Plates 78 and 79.

The ends of struts should not be notched into uprights unless
the latter have a considerable margin of strength and stiffness.
Uprights and struts should be notched into groundsills and
capsills when possible ; but when time presses and few car-
penters are available, a careful arrangement of dogs will suffice,
without notching.

293. PI. 78, Fig. 4, shows a corbel, an arrangement for giving
a wider bearing at the top of a trestle ; and Fig. 5 an alternative
method, which also helps to fix the capsill.

294. Dogs, spikes and bolts are the most useful fastenings
for framed trestles. The position of each dog should always
be considered with a definite object of preventing a possible
distortion of the frame. They should be on both sides of the
trestle. Dogs should not be driven within 3 inches of the edge
of a timber, or within 4 inches of its end.

Spikes, when used in pairs, should be driven inchning
towards each other. They run 5 inches to 10 inches in
length.

J>laJbe78

Fig1

rRAMED TRESTLE

Squared Timber

f-^'SX-A

Tt^ 2

Fi^ 3

wrong position^
for dog.

Fj^,^

Fvg 6

n;^ a a

Composite roadhearers
wittcplxviks fhreaJujiq Joint

■Welleri Graham L!f Lirtw. London

C)j)posvte page J^-^

ricute 79

FRAMED TRESTLES

Sleepy j.,se'.^

Fistcp
5 coaxifv scTt

Tresile with. \'
ilsTv phite g-^^^
rastemn^s

t boU

Vf'drvri%oUs ''^gdrU'-ii'olts ''/a'^drift l>oUs

-^M ' m^

FICLTV

Trestle of Flouaks

CapsilL ^^J-ron stiiap.

Wel!er46raham.l'* Liffto, London.
JhfoUxfyy pZate 78:

PlcLte SO

FRAMED TRESTLE

Round Timbers

"''' "" ~" •*" ' •''T^rfiiTr-ff^r4r;7-;;iri7r

Fi(j. 2

ELe\'aJLiorv

To foll<ryv pbxte 79

CHAPTER XX. — FRAME BRIDGES, ETC.

113

295. When round timbers are used the groundsills and capsills Framed
must be adzed to give a square bearing surface for the trestles of
uprights. I'pund

When there are two or more tiers, it will be best for the ^^ ^^'
upper tiers not to have groundsills. The uprights may rest
directly on the capsills of the tier below {see PI. 80.
They should be wedged up after fixing ; to keep the trestle
together while it is being raised, a light timber or board may
be spiked to the sides of the uprights near their feet.

296. Formula for Use in Suspension Bridges.

Suspen-
sion
bridges.

Length of cable between piers = a +- —

W cr

W=. uniform
dead load on
y cables per
un of

Tension in cable, Tq

Tension at piers, Tg

Pressure on piers = W a J

Height of frame d •= -\- h' (length of centre sling) + camber (1 in 30)

For a concentrated load, such as that brought by a traveller, without

Ad
roadway, safe load on the cable = — x working- strength of

cable.

(5289)

CHAPTER XX. — FRAME BRIDGES, ETC.

297. The followinf;^ table will be found useful for calculating stresses
due to uuiform loads on suspension bridges ; in it the load is \Vx a : —

Dip.

Tension at
lowest point.

Tension at
highest
pcint.

Length of
cable.

Depression at

centre due to

an elongation

of cable of

1 inch.

Ta^ue of
JK.

a
10

1-25 X lead

1 -346 X load

1 -027 X span

1 -875 inches

2o SK

a
ll

1 -375 „

1 -49

1 -022

2 -0625 „

2-75 „

a
12"

1-0

1 -58

1 -0185

2 -25

3-0

a
13

1 -625 „

1-7

1 -0158

2 -4875 ,,

3 •25 „

a
14

1 -75 „

1 -82 „

1 -0136

2-65

3-5 „

a
15

1 -85

1 -94 „

1-012

2 -815

3 -75

298. For length of slings^ = -^ x~.

a = span.

cl = dip.

y = length of sling,

X — distance from lowest point in fee.

Anchor- 299. Pull on anchorage = tension in cables at piers,

age. Strength of log anchorage (Fig. 9. PI. 48) = holding power

of the anchor face, and can be obtained from the following

CHAPTER XX. — FRAME BRIDGES, ETC.

115

table, showing" the holding power of dry loam at varioiuj
depths and inclinations of cable ; —

Mean depth of Face of

Anchorage below

Surface.

Inclination of the force drawing the anchorage
(in a direction perpendicular to its face),
and corresponding ultimate resistance in
lbs. per square foot of anchor face.

2 feet

3 „ ..

4 „

5 »

2,700

4,400

8,000

22,000

3,880

5,860

10,660

29,330

4,032

6,160

11,200

30,800

4,370

6,750

12,260

33,730

300.

jS'ature of Soil.

Relative Holding
Power.

Compact loam, rammed (dry) . .

Hard compact gravel, rammed (dry) . .

Wet river clay (below subsoil water level), rammed

Incoherent river sand, not rammed (damp) . .

0-9
0-5
0-5

301. A 3. 2. 1. holdfast, made of 5 feet park pickets, driven
2 feet 6 inches to 3 feet in the ground, should stand a strain
of 2 tons [vide PI. 48).

302. The following detail shows the most convenient way Cask piers.
of making cask piers with large casks, see PI. 54.

The gunnels should, for a pier of the size shown in the figure G-unnels.
(the casks used being butts), be 21 feet by 4 inches by 5 inches.

The slings of 2J-inch rope, 6 fathoms long, with an eye splice Slings.
1 foot long at one end.

(5289)

H 2

116 CHAPTER XX. — FRAME BRIDGES, ETC.

Braces. Braces of IJ-inch rope, 3 fathoms long, a small eye splice

at one end, and a figure of 8 knot 1 foot 5 inches from the
eye.

Ways. The pier being made, is launched into the water by means of

a sledge called the ways.

Forming To make a pier the number of men required is two more than

piers. double the number of casks, or 2 n + 2, where n is the number

of casks.

Four men stand at the ends of the gunnels, the remainder
opposite the intervals between the casks on either side. The
gunnels being in position, the gunnel men at one end place the
eyes of the slings over the gunnels ; the gunnel men at the other
end secure the slings to their ends of the gunnels with a round
turn and two half hitches. The brace men keep the slings
under the casks with their feet, and as soon as they are secured
adjust the braces as follows, the men working simultaneously
by word of command.

The eye of the brace is passed under the sling in the centre
of the interval between two casks, the end passed through the
eye and hauled taut, the sling being kept steady with the left
foot. The brace is then brought up outside the gunnel im-
mediately over the eye, and a turn round the gunnel taken to
the left, the foot is removed from the sling, and each man then
hauls up the standing part of his brace with the left hand,
holding on to the turn with the right ; as soon as the brace
is taut the turn is held fast with the heel of the left hand, and
the remainder of the brace, in a coil, is placed on the cask
to the left. Each man then takes his opposite neighbours
brace from the cask on the right, and passes 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 bight
so formed below the figure of 8 knot on his own brace, and
placing the end on the cask to 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 his foot against
the gunnel, and hauls taut. The pier is then rocked backwards
and forwards, all the brace men taking in the slack of their
braces and hauling taut until the word steady is given^ when

CHAPTER XX. — FRAME BRIDG^ES, ETC. 117

they take a round turn round the gunnel to the left of the previous
turns, and make fast with two half-hitches round the two
parts of their own brace close to the gunnel, drawing the two
parts close together and placing the spare ends of their brace
between the casks. The pier is then turned up on one side,
and the sling adjusted below the third hoop of the casks, and
a breast line attached to the slings at each end : it is tlien lowered
and turned up on the other side, the other sling adjusted, the
vmys brought up into position^ and the pier lowered on to them
ready for launching.

118

CHAPTER XXI.— DEMOLITION FORMULA.

CHARaES FOR HASTY DEMOLITIONS.

Note. — The charge is in lbs. B = length to be demolished in feet.

T = thickness to be demolished in feet.
i = thickness to be demolished in inches (in the
case of iron plate only).
In the presence of the enemy increase the charges bj 50 per cent.

GUNPOWDER (Tamped).

Object attacked.

Brick arch — one haunch
Brick arch— crown . .
Brick wall
Wood stockade — hard wood

Stockade of earth between
timber up to 3 ft. 6 in. thick

lbs.

Fort gate
Tunnels

fBT^
|BT2
|BT2

40 to 100

60 to 80 per
5 ft.

200
tT3

Remarks.

' Total amount divided into
charges placed apart about
twice the thickness of brick-
work.

One charge. Soft wood half
this.

One charge.

Where T = total distance from
the surface of the lining to
the charge.

Note.

CHAPTER XXI.— DEMOLITION FORMULAE.

CHAEGES FOE HASTY DEMOLITIONS.

-The charge is in lbs. B = length to be demolished in feet.

T = thickness to be demollsbcd in feet.
t = thickness to be demolished in inches (in the
case of- iron plate only).
In the presence of the enemy increase the charges by 50 j^er cent.

aUNGOTrON (Untamped).

If the charge is tamped, decrease by one half.

Obje<;t attacked.

lbs.

Eemarks.

Brick arch— haunch or crown..

fBT=

Continuous charges.

Brick wall— up to 2 ft. thick . .
Brick wall— over 2 ft. thick . .
Brick pier . .

2 per foot
1BT2

1 Length of breech B not to be less
)■ than the height of the wall to be
brought down.

Hard wood — stockade or single

3BT2

In a single charge outside. For"^ .«
a round timber charge = ST^. :g

Hard wood — necklace . .

3BT2

Trees up to 12 ins. diameter. For ! ^

a round timber charge = 3T^ j "o

Hard wood — auger hole , .

Stockade of earth between tim-
ber up to 3 ft. 6 ins. thick
Heavy rail stockade

|T2
4 per foot
7 per foot

Where the timber is not round, ^S
T = smaller axis. J ^

)■ Single charge.

Fort gate

1
J

Breechloading guns

For S-inch gun use 2 lbs. Double
the charge for every inch increase
in calibre. To be placed in breech.
The gun should be loaded with a
shell if possible.

First class rail . . . .

—

PA third of a If -lb. slab against the
\ web near a chair if those are used.

Iron plate

|B^

t is in INCHES.

Iron girders . . * .

fBjf2

r Calculate as for iron plate, given .
< thickness of flange to be measured
[ where it joins the web.

Frontier tower, stone and mud

16 to 30

In one charge in centre of tower.

Wire cable

■ " C " being the circumference in
inches.

120

WORKING

Nature of Work.

Dimensions.

No. of lien.

. Felling trees

. Cutting brushwood

Clearing plantation of brush-
wood, with trees up to 12 in.
diameter; sorting, binding,
carting

Cutting hedge

Making fascines

Gabions

Band gabions

Hurdles

Cutting sods

10.

Loophole in wall, two bricks
thick

Jl.

Notch, two bricks thick

12.

Abatis, roughly constructed ...

13.

Low wire entanglement

14.

High „ „

Up to 1 ft. diameter

Up to about 1|" di-
ameter

Time.

100 yds. X 40 yds. ! 1 company (100
men)

Wood, ^" to 2" diameter
18' long, 9" diameter

1 man

5 men

2' 9" high, 2' external
diameter

2' 9" high, 2' diameter
6' long, 2' 9" high

18" X 9" X 41"

50 yds. deep

3 „
1 man

10 men

1 minute per inch
of diameter

4 hours

minutes to 18
uaautes

1 hour

2 hours

10 minutes
2 1 hours

i M

10 minutes
1 relief
1 hour

4 hours

N.B.— Gabion revetments, 7' 6" high, requires 14 gabions, 3 fascines per
HurdleJ or brushwood, 2' 9" high, requires 9 bundles brushwood,
Sandbag revetment requires 200 sandbags per 100 gup. feet.
For constructing iiead corer, sandbags and sods, on earth parapets,

PARTY TABLE.

121

Amount.

100 sq. yds. or 9 to
10 bundles of
60 lbs. each

About 300 bundles
of 50 lbs. each

2 paces

ICO

2 paces
100 sq. yds.

Tools.

Felling axes: hand axes;
saws, cross-c«t; saws,
band

I Billhooks, lashing or wire;
I a small portion of felling
)■ axes, hand axes and saws ;
a grindstone and a few
I whet stones

Billhooks and hand axes

1 measuring rod; 1 dicker;
3 billhooks: 2 knives ; 1
maul; 1 hand saw; 1 pair
of pliers

1 billhook; 1 mallet; 2
knives; 1 measuring
rod

2 billhooks; 2 knives; 1
mallet ; 1 pair of pliers (if
sewn with wire)

Sharpened
cutter

pades or sod
Crowbar or pick

3 billhooks; 1 maul ; 2 pairs
of pliers

20 yds. length. i 2 billhooks; 2 mauls; 2
pairs of pliers, 1 hand saw

Remarks.

For larger trees the diameter in inches cubed
and divided by 144 will give the number of
ndnutes. With the hand axe allow 2 minutes
per inch of diameter lor trees up to 1 foot;
for trees over 1 foot twice the calculated
amount.

Men opened at 4 yds. interval should cut
25 yds. to their front in 4 hours.

40 men cutting; 40 men sorting and binding;
20 men cartuig.

If very bushy a pole and ropes can be used
to expose their lower branches to the axe.

Materials : 4 bundles brushwood. 60 ft. of wire
or spun yarn if withes are not used. Weight
about 140 lbs.

One and a half bundles of brushwood. Weight
complete about 50 lbs.

10 bands, 10 pickets. Weight compl'ite, 13 lbs.

Trees used where felled.

1 sq. ft. of entanglement takes 1 ft. of wire.

sq. ft. takes 3 ft. of wire. Entanglement
built with 3 rows of pickets, each 2 yds. apart.

100 sup. ft.

wire and stakes for anchoring per 100 sup. ft.

allow ^ hour to 1 hour in addition to the calculated task.

122

CHAPTER XXII. — ROADS — BONING AND LEVELLING.

.£

'B
o

<4-l

o .

1°

1
i

Above or
below
datiini.

A iH W O

^ (N cc O

III

^ 1 '

d rH 1— 1
'^ 1 1

C<1

ft. in.
lino (or start

5 1

6 2
3 10

I— i
r-i

1 y^ m

ft. in.

3 0
5 1
G 2

Horizontal
distances.

ft. in.

5 0
10 ()

8 2

7 10

o 1

1
" 1

?5 * * '

<'i o ;:; s

: 1

123

CHAPTER XXII.— ROADS -BONING AND
LEVELLING.

Roads.

303. A roadway 10 feet wide (8 feet minimum) will take a width of
single line of wagons* passing in one direction, or infantry in roadway,
fours ; 12 feet is better as allowing horsemen to pass without
difficulty ; for each additional line of vehicles 10 feet should be

added to the width of the road.

Where there is little traffic, a width of 10 feet may suffice
for wagons both going and coming, provided sidings are made
at intervals, into which one wagon may go to allow another
to pass.

A width of 6 feet is sufficient for infantry in file or pack
animals moving in one direction.

304. The gradient for a short distance, such as a ramp leading Gradients.
on to a bridge, may be ^, or even J for infantry, i for artillery,

but for animals or wheeled traffic slopes steeper than ■:^\ are
inconvenient, and if the incline be long it is still more desirable
to reduce them. Traction engines will, on good roads, draw a
load equal to their own weight up ^q, twice their own weight
up 2V5 ^^d three times their own weight on the level, or up
slopes not exceeding J3, which is the maximum gradient
in first-class roads.

305. Whenanew road has tobeconstructeditshouldbemade Laying
as straight as is consistent with the extreme gradient permissible, out a new

In laying it out the centre line should be marked by pickets, ^^^^'
spitlocking [i.e., marking out the fine with the point of a pick),
&c.

If the road passes through a wood, it will be well to cut down
a fine of trees in the required direction. The space occupied

* The ordinary -width of the wheel track of W.D, carriages is 5 feet
2 inches from out to out, except that of the pontoon wagons, which is
5 feet 10 inches.

The points of the axletree arms project about 6i inches beyond the
wheel track on each side.

]2i CHAPTER XXII. — ROADS — BONING AND LEVELLING.

by the road should then be cleared of all irregularities, and the
tree roots grubbed up.
Metalled 306. Fig. 1, PI. 81, gives a section of a metalled road on level
'^^^* ground, or only slightly inclined in the direction of the width

of the road.

Side drains must be cut where necessary, and communications
made underneath the road at intervals to allow the water
to escape. The earth from these side drains, when well rammed,
may be employed to give a shape to the road if metalling
is afterwards to be put on to it, otherwise it is better scattered.
In applving the metalling large stones should be spread as a
foundation, and above this should come a layer of broken
stones some 3 inches or 4 inches thick. A thin top layer of
gravel or other binding material is an advantage. This should
be rolled or rammed, a plentiful supply of water being used.
The surface of the road should slope from the centre to the
side at about ^V' ^^ allow the water to drain off.

Sometimes only one layer of stone of the smaller size is used.
In many situations gravel is the only available material ;
it should contain a portion of loam, sand, or other small stuff
to bind the pebbles together.

AMiere metal is not obtainable, such growths as reeds, heather,

or long grass, laid thickly across the road are better than

nothing.

Eoad on 307. AMien on the side of a hill the road will be partly cutting

"^f ^^ and partly embankment (Fig. 2), unless the hill is very steep,

when it may be all cutting as in Fig. 2, PI. 82.

The ground on which the embankment rests should be
stepped, to prevent slipping, and a retaining wall of dry stones
(Fig 2, PI. 81) or logs, fascines (Fig. 1, PL 82), or sods, &c.,may
sometimes be required. The surface of the road should slope
inwards towards the hill, the water being got rid of at intervals
bv drains passing under the road. If no drain pipes be available,
French drains may be constructed by digging a trench and filUng
it with large stones fitted loosely, so as to allow the water
to pass through, the top being covered with brushwood, which
carries the roadway. Serviceable drains may also be made
with barrels or planks.

When ascending a hill by means of zig-zags the road should
he m&de as level as possible at each angle, and half as wide

hill.

PlccteSJ

METALLED ROADS.

^i^,1.

K "5 --4«»i*-^ '-'^-T/ss- ^ o "- -

Fi^.Z.

^ r-3'*^'—}?^-^'^^' O' ■>j^-^;e>i

J^z^.S.

Weller 4 Graham. W LithaLonaon.
Opposite' poLg^ J24-.

Plat^SZ

TEMPORARY

ROADS

Tis^.7.

j^ .<^ '-.„^r --^"

'_f

gug^gdilg^M

•

^^^,.^^i%l

/ JFl^.Z.

6talt orvJFcLSctrves.

'^-^^- f8 0'-

-tf'd

\ 1^^ 1 iJ'."J ^^^JO^^i^'Tj

1 ' 1^'"^ ijL<.U,,jJt^..

'w^n

I^^j^ffl^wjy ^ jPF?^^:^^^

iwft,

._, •••-■*T^' ■ '- *

siasB OS.

Welter 4 Gp«h»m.L>^ Litha London.
TofoUxrw plccUSi

CHAPTER XXII. — ROADS — BONING AND LEVELLING. 125

again as in the straight portions. Short zig-zags should he
avoided.

308. When a road passes over verv wet or marshy ground, and 'Roa^s
brushwood is available, it should be made up into fascines across
or hurdles, or even laid loose across the road (though this ^^^^^nes.
plan is not so good as if made up) as foundation for the road
material.

309. When fascines are used there may be one, two, or more Fascine
layers (Fig. 3, PI. 82), according to the requirements of the ^^o^^-
case, the top row being always at right angles to the direction

of the road.

310. With hurdles their length should be equal to the width Hurdles,
of the road, and there should not be less than two layers across

the road, the layers breaking joint.

When the road is a permanent one it is considered ad-
visable to place the brushwood at such a depth below the surface
as will ensure it always being damp, as when it is alternately
wet and dry it soon rots.

Four inches to six inches of broken stone or gravel are then
laid on top, or, if these materials be not available, the earth
excavated from the trenches on either side is thrown there,
the surface being sloped as already described.

311. The trenches should be cut about 3 feet or 4 feet from Trenches,
the brushwood on either side, and outlets should be made from

them at intervals, to allow the water to discharge into lower
ground.

312. See Chapter XII. Corduroy

road«.

313. Eoads which are exposed to the traffic of heavy military Repair of
vehicles require constant repair. Parties of men under a ^°^^^*
N.C.O. should therefore be told olf to every 3 or 4 miles of

road to keep it in order, and depots for road metaUing should
be formed at short intervals from which the material is dis-
tributed along the road as required. The material used may
be either broken stone (of a size to pass through a 1 J-inch ring),
broken furnace slag, brick or gravel, which should be apphed
in thin layers, the surface of the road being first loosened
by scoring it with, the pick.

Tools. — Shovels, picks, rammers, measuring rods, levels, Tods.
&c. ; also, to break up the metalling, stone hammers 3 lbs.

126 CHAPTER XXII. — ROADS — BONING AND LEVELLING.

in weight, with handles 2J feet long, so as to work standing,
or of H lbs. weight, with handles 18 inches to 2 feet long, to
work sitting.

Boning and Levelling.

Levelling by means of Boning Rods.

Definition. 314. It is often necessary in the field to make a rough section
of a piece of ground or parapet, so as to calculate the amount
of work to be carried out, or to lay out short lengths of ground
at a given slope, as in road-making, drainage, &c. For such
purposes levelling by means of boning rods may be employed.
Tools. 315. The tools required for boning are a field level (or a

mason's level, or a spirit level with a straightedge), a mallet,
pickets, measuring tape, a set of three boning rods, and where
great differences of level are met with, a long rod graduated to
read feet and inches.
Mason's The mason's level is sho\\Ti in Fig. 1, PI. 83, and can be made

level. by any ordinary carpenter, where a field level is not available.

Boninc Boning rods are usually made of deal, 3 inches wide and

rods. I inch thick, and consist each of a long arm, with a head

dovetailed on at right angles to it (Fig. 2, PL 83). Care must
be taken that all of a set are of exactly the same length.

316. To make a section with such rods, it is usual to select the
highest point of the section and there drive in a picket flush with
the ground, driving in a second picket on the line of the section
with its top carefully levelled to the top of the first picket (by
means of the field, mason's, or spirit level), and as far away
from the first picket as the length of the level or straightedge
\\dll allow {see A, B, Fig. 3, PL 83). It is evident then by look-
ing over the tops of the two pickets (A, B), the depth below
the line of sight of any other points (C, D), on the section could
be determined by holding up a measuring rod at those points,
and the horizontal distance apart of the various points being
also measured, a rough section could be made. To avoid the
obvious difficulty of getting one's eye down to the top of the
first two pickets (A, B), boning rods are set up on them, and
a third boning rod (or the long rod) is set up at the different

:Plcxjtie< (S3

BONING & LEVELLING

-Z^.^.

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JFigr.

-e — -i^ ;' TO — i

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H^kt, ang^fes to t^.ev^pTy)pej^ positiok

5186 l. OS.

Wcl!er& Graham. L<:'? Litho. London.

Oppos tte pa^e J2G.

M4xte^84.

Field Level

Fi^.l.

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TcfolUnv plyjct^ 94.

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Plate SG

Field Level

IbfoUawplxiteSS

CHAPTER XXII. — ROADS — BONING AND LEVELLING. 127

points (C, D, E) whose level is required to be known. The
boning rods being all of the same length, give by their tops
a horizontal line parallel to the first line of sight, but 3 feet
(or thereabouts) above It. In the same way a given slope
(say y^^) can be set out (i'ig. 4) by arranging the tops of the
first two pickets at the required slope (level A and B, 10 feet
apart, and then cut 1 foot off B), setting up two boning rods
on them, and by means of the third boning rod driving in
pickets to show the top of the slope at any required points,
N, 0, P. Again, a continuous slope between any two points
can be laid out with pickets, as in Fig. 5, by putting the firsfc
boning rod at F, the second at G, and with the third rod setting
up the intermediate pickets.

317. In taking a section it is usual to enter the levels, &c., Taking
in a book {see page 122). section.

Field Level.
318. The field level is shown in Plates 84, 85, and 86.

It can be used when closed —

(1) As an ordinary spirit level for boning, levelling, &c.,

the spirit level being on the edge of the limb C.
(Fig. 1, PI. 84.)

When open —

(2) As a square for setting ofE right angles. (Fig. 1.)

(3) As a protractor for setting off angles. (Fig. 2.)

(4) For setting off slopes of all grades, and as a mason's

level with plumb bob. (Fig. 1.)

In all cases place the limb A against the slope to be
measured.

The dotted Unes in Fig. 1 show how the instrument is
closed.

N.B. — One edge of the level is graduated in feet and inches.

128

CHAPTER XXIII. — RAILWAYS AND TELEGRAPHS.

CHAPTER XXIII.— RAILWAYS AND TELEGRAPHS.

Railways.

Forma-
tion.

Forma-
tion level.

Width of
railway.

Gauge.

319. The duties likely to be required of troops in the field
with re.^-ard to railways (apart from large railway schemes,
for which special arrangements would be necessary) may be
considered as either temporar}^ repairs, or the laying of short
lengths of line to join up breaks, the construction of addi-
tional works such as platforms, &c., to adapt the line for
military use, or the demolition of an existing line.

320. The formation includes the whole of the earthwork
necessary to complete the line to "formation level" and
secure the required width of way together with "side" and
" catchwater " drains, and any " retaining walls" or protective
works to secure the bank against floods. Tuimels are included
under the head " Formation."

321. Formation level means the level of the completed surface
before the ballast is put on. On rapidly constructed military
lines, where ballast is possibly not available, the formation
level would be the depth of the rail and sleeper below the
rail level. The formation level is not absolutely horizontal
transversely, as it should slope slightly downwards from the
centre line towards the sides of the bank or cutting for
purposes of drainage.

322. The width of the railroad depends on the gauge, the
width of the rails, the clear space outside the rails and the
space necessary for drainage.

' 323. The gauge is the shortest distance between the inside
edges of the upper surfaces of the rails, and is | to 1 inch
greater than the distance between the flanges of a pair
of wheels.

In Great Britain, and most of the European countries, the
ordinary gauge is 4 feet 8 J inches ; in Ireland, it is 5 feet
3 inches ; in Russia, 5 feet ; in British India, 5 feet 6 inches
(metre, 3 feet 3| inches) and 2 feet 6 inches.

For a 4-feet 8j-inch gauge, single hne, the minimum width
of banks and of cuttings at formation level should not be less
than 12 feet and 16 feet respectively. These dimensions

CHAPTER XXIII. — RAILWAYS AND TELEGRAPHS. 129

might be taken for gauges of 3 feet 6 inches, or metre gauge
(3 feet 3| inches). For a 2-feet 6-inch gauge these miuimuni
dimensions might be reduced by 2 feet. For every additional
line of rail it is necessary to add the gauge plus two rail-
heads, plus a way between the tracks such that two vehicles
can clear each other witli their doors open and a little to
spare — say 11 feet for the 4-feet 8j-inch gauge.

324. General type of first-class English railwa}': — Perma-
i?«/Z5.— Steel double- headed, weight 80 to 90 lbs. per '^^^^ way.

yard.

Sleepers. — Balric fir, 9 feet by 10 inches by 5 inches
(PI. 87, Fig. 2), weight 140 lbs. ; laid 3 feet apart
centre to centre, 2 feet 2 inches at rail joints.

Chairs, — Cast-iron ; width 6 inches or 8 inches ; weight
45 lbs. each ; secured by two steel spikes and two
screws. (Fig\ 4.)

Keys, — Compressed oak, 6 inches long. (Fig. 4.)

Fishplates. — Steel ; weigJit 54 lbs. per pair ; secured
by four steel bolts | inch diameter. (Fig. 7.)

Ballast. — Screened cinders, broken granite or slag,
size not exceeding 1^ inches cube, nor more than
10 per cent, to pass -^-inch mesh. Rounded gravel,
if used, to be mixed with sand or broken stone to
prevent it from working out from under sleepers.

In most foreign countries, however, the flatjooted or
Vignoles rail is used. This does not need chairs, and is
spiked direct to the sleepers, sometimes with a bearing-plate
between if the timber is of a soft description.

325. Two of the many different kinds of rails in use are shown EaiK
on Plate 87, Figs. 5 and 6, the double-headed and the flat-
bottomed rails are usually made in lengths of from 15 to

30 feet, or even 60 feet, and weigh up to 110 lbs. per yard for
permanent lines intended for heavy traffic.

326. The rails are connected together by two fishplates of Rail
wrought iron or steel, each with four bolts with nuts and joints.
washers. The sleepers on each side of the joint are brought
closer together so as to reduce the bearing to about 2 feet.

(5289) I

130

CHAPTER XXIII. — RAILWAYS AND TELEGRAPHS.

Sleepers.

Ch lies.

Connec-
tion

between
chairs and
sleepers.

Connec-
tion of
rails with
chairs.

Connec-
tion

between
rails and
sleepers.

Ballast

327. Sleepers are bearers, whether of wood or of steel, used
to distribute the weig-ht on the rails over the ballast or
roadway, aud in the case of cross-sleepers as a connection
between the two rails to preserve the g"auge.

Each mile of railway requires 1,850 to 2,000 sleepers.

328. Chairs are used to connect the rails to the sleepers,
when necessary owing- to the sectional form of the rail,
and to distribute the weig-ht over a greater bearing area
on the sleeper than is obtained by the rail resting on it.

329. Chairs are fastened down to sleepers by spikes and
treuails.

Trenails are wooden spikes, so compressed by machinery
as to expel all moisture from them. When they have beea
driven into the sleepers their tendency is to absorb moisture
and swell, and so to grip the sleeper more tightly. They
must not be employed alone, but where they are used there
should be at least one iron fastening to each chair, for,
although the trenail is a firm means of holding down the
chair to the sleeper, it is liable to rupture from a shearing
stress. For this reason, oak trenails with iron spikes driven
into them (PI. 87, Fig. 3) are often used.

In the case of flat-footed rails with good bearing area aud
exposed to moderate axle loads, the rails may be spiked direct
to the sleepers without chairs or bearing -plates.

330. The double-headed ;md also the bull-headed rail is
held in its chair by a key or small block of wood, compressed
b}' machinery (Fig, 4). This key is slightly wedge-shaped,
and is driven firmly into the gap in the chair at the side
of the rail. Rails may be ke3'ed on the outside or inside.

331. Flat-footed rails are generally connected directly with
the sleepers by dog-spikes, or with the interveutiou of
hearivg-plates.

332. Ballast is broken scone or other suitable material
placed on the formation level, on which the sleepers rest,
and with which they are " packed " to the proper level
or inclination.

The objects of ballast are: —

i. To distribute the pressure imparted to it by the
sleepers over a larger area.

PZoJUSl

RAILWAYS

>Y7. Sr—Z^. O^.

FzQ.3

Flge.

13^' -

ried^

J^.7

^S^

StSS.9M»Sm

Weller I. Graham. U?' Utfco. London.
Opposite pcLff» /^^(

P7<jcte6S.

RAILWAYS

Fi^ 1

Points of ^witches

nnnnnnn uuu

Fi^.Z

Cross over Road

Fi^.3.

Crossing

y/vn^

.^^^^^^L

9lti6 S. PS

WtUer & Graham. L'f Umo.London

CHAPTER XXIII. — RAILWAYS AND TELEGRAPHS. 131

ii. To keep the sleepers dry, by affording a permeable
mass for rainwater to pass through, and thus
prevent their decay.

iii. To afford faciUties for packing under the sleepers
when they have sunk.

The ballast is usually laid to a thickness of about 1 foot,
or 18 inches in very wet places ; the permanent way is then
laid on it, and its thickness is afterwards increased to tlie
height of the bottom of the rail. The two layers are called
the bottom ballast and the top ballast or boxing.

In field railways the bottom ballast may be required for
drainage, but the top ballast could be omitted. As a temporary
measure ballast could be dispensed with altogether.

333. Any railway tools or materials found along the line Eailway
must be handed over to the officers in charge of repair, and tools and
not on any account appropriated by troops. materials.

Railway Repair and Reconstruction.

335. The main principles on which the work of repair and General
reconstruction is carried out are : — principles

(1) To make the speediest temporary repairs possible, of^^-gii^^"^

{e.g., deviations and low-level bridges) in order to get ways. "
a line of some sort through with the least possible
delay.

(2) Simultaneously to commence high-level trestle bridges

on concrete foundations where required in order to do
away with the disadvantage of lojig deviations with
sleep gradients and sharp curves.

(3) To commence, without any delay, all permanent repairs,

viz., rebuilding the masonry, repairing the girders,
or replacing tliom with new ones in order that the
line should be as soon as possible restored to its
former position and entirely safe against floods.
335. The best system to adopt whereby to carry out rapid Construc-
repairs is to establish " Construction Trains." The recoustruc- ^^^^}
tion staff hve in these trains, which gradually advance along ^^'^^°^'
the line as it is being repaired, conveying also the necessary
material.

(5289) I 2

132

CHAPTER XXIII. — RAILWAYS AND TELEGRAPHS.

Material
depots.

Wagon
transport
at rail-
head.

Labour. 336. P^or railway work of any magnitude Jarg-e gangs of

unskilled labour are required, and this is especially true of
temporary re[)airs to be executed rapidly.

The proportion of unskilled to skilled labour -on temporary
repairs is as 7 to 1 ; on semi-permanent and permanent
repairs as 3 to 1.

337. An advance depot for railway material and stores must
invariably be formed at some place within 50 miles of tha
starting pr jnt for repairs, and that before work begins.

338. [Sufficient wagon transport to carry 60 tons should, it
possible, be available at railhead to allow an advanced party to
move on, repairing minor breaks. Much time is thus saved.

Night 339. Provided that the arrangements for lighting works at

work. night are good, an equal amount of work can be done by day

and night shifts, and when repairs are being pressed, day and
night shifts are essential. The only class of work which
cannot well be carried on by night is platelaying, which
requires plenty of light along the track.

Flares, oil, or acetylene, are easily manipulated and give
good light for working parties.
Tern- 350. Up to 18 feet height. Crib piers of sleepers make

porary satisfactory bridges, which are rapidly built, as a large number
bridges. qJ jj^^jj Q^n be employed to handle materials.

Between 18 and 25 feet, the speed at which such bridges can
be built decreases rapidly, not only on account of the additional
height, but because more material is used.
Water 341. Damages to water supply by the eneniy is apt to cause

fc^pply- much difficulty. Troops must not use railway water supplies
without special authority. A steam pump and boiler cariied.
on a truck is a useful adjunct. Lift and force pumps worked by
manual power, each with several lengths of hose, should also-
be carried. Engines can then make shift with temporary
watering ariangements.
Tern- 3^2. To provide for entraining or detraining animals,,

porary vehicles and sruns, extra siding and platform accommodation
^ will become necessary at various points.

The sidings would be in extension of existing sidings, or
branch f i om the main line, according to circumstances.

The p/at/orms would, as a rule, be most conveniently placed
alongside a siding of sufficient length to allow of the train

CHAPTER XXIir. — RAILWAYS AND TELEGRAPHS. 133

being shifted so as to bring- different vehicles alongside in
succession.

Almost any available material may be used, but perhaps the
most rapid method of construction is to make a crib work of
-sleepers (or similar baulks) and rails, or of sleepers only,
decked with sleepers, or planking of sufficient thickness to
carry the anticipated loads.

The edge of the platform must be just sufficiently far from
the rails to allow trucks and carriages to pass, and the top
should be level with the truck floor. No over-hang need be
^iven. The decking should usually be held down by ribands
along the edges.

One or more inclined ramps will be needed at the back or
ends, according to length.

Telegraphs.
(The term Telegraphs includes also Telephones.)

343. Special troops are usually employed in the construction Line,
of telegraph lines, but it is as well that all should have a shght
knowledge of the principles of construction, if only with a view

to producing the greatest possible damage to the lines when
demohshing them.

344. For the transmission of messages by electric telegraph it
is necessary to have a continuous insulated conductor connecting
the various stations in communication.

345. By a conductor is here meant a metallic substance for Con-
conve\ang the current. For this purpose galvanised iron, ductor.
copper, or bronze wire is generally used, either as a single wire

or a smaller number of wires twisted into a strand, as in a rope.

346. By "continuous" is meant that the conductor must Con-
not have the smallest break in its metalhc continuiy. The tiauous.
wire is necessarily suppHed in coils of convenient weight, as it
would be too heavy to manipulate if in one length. In the
joints however, metalhc continuity is ensured by soldering.

347. By " insulated " is meant that the bare conductor Insulated,
must not be allowed to touch the earth, or any neighbouring

^vires, or any substance of a conducting nature which may be in

134 CHAPTER XXIII. — RAILWAYS AND TELEGRAPHS.

connection with the earth or other wires. This is effected
usually either by " aerial Hues " or by " cables."

Aerial 348. An aerial hne consists of a wire suspended on insulators

of porcelain or glass, supported on poles placed at about
60-yard or 80-yard intervals. The poles should be of such
height as will keep the wire clear of obstacles and traffic,
and safe from malicious damage. No wire should be less than
12 feet from the ground.

Insulators. 349. The insulators are shaped like inverted cups having one
or more grooves round them. Porcelain insulators are usually
fixed to the pole or arm by means of iron bolts, the cups being
provided with an internal screw thread to fit the top of the
bolt (PI. 89, Fig. 2).

Wiring. 350. In erecting the line the wire is first stretched con-

veniently tight over several poles. It is then placed in one of
the grooves of the insulators and " bound in " securely with
a piece of smaller wire or tape binder ; thus at ordinary
insulators there is no break in the continuity of the wire.

Wires for telegraph circuits are invariably run straight^
that is to say, their insulators occupy similar positions on each
pole. On the other hand, important telephone circuits require
two wires, each of which revolves or twists round the other,
though of course they are kept well apart.

Poles. 351. The poles may be of iron or wood, usuallv the latter.

They should be buried in the ground to one-fifth their length,
and their tops protected by a piece of galvanised sheet iron
termed a " pole roof."

Arms. 352. ^Vhere more than one wire is carried on the same line of

poles, the ^vires are attached to insulators fixed on wooden or
iron arms, let into the pole, and at right angles to it (PL 89,
Fig. 1). The length of the arm depends on the number of
wires to be carried. When more than one arm is required they
are usually placed at vertical intervals of 1 foot.

Earth 353. Wooden poles, except m dry rocky ground, should be

wires. provided with earth wires, consisting of a piece of iron wire
running down the pole, under the head of each arm-bolt to the
butt, where it is stapled in the f o^m of a small spiral ; this
ensures the earth ^vire being well under ground. Each of the
arms is wired, and a turn of the wire is taken round the arm

JP^ae^^ 89.

TELEGRAPHS

"ar^thyxnj^e^

r1.

^- 3.

J'oZe/ ^r-ctchets.

s/eS.e.os.

We(fer&Gr3h»ni.L«! Litito. London.
To fcLce^ pa^0 134

CHAPTER XXIII. — RAILWAYS AND TELEGRAPHS. 135

between each pair of insulators. This wire is also brought
under the nut of the bolt which secures the arm to the pole.

Earth wires serve a dual purpose ; they protect ths poles
against lightning, and prevent the current from a faulty wire
leaking to other circuits, the current being conveyed by the
earth wire direct to earth.

354. "\Miere, from the pull of the wires, wi :d pressure, and stavs and
other causes, the poles are likely to be forced out of the vertical, stmts,
they should be stayed. Sta3^s are formed of stranded iron

wire firmly anchored in the ground and attached to the pole
about 2 feet from the top. When the pole carries a great
number of wires a second stay may be required, in which case
it is added below the first.

In situations where it may not be convenient to fix a stay,
a strut can be erected in a similar position, but on the other
side of the pole. Struts are usually about two -thirds the
diameter of the poles they support.

355. Insulators are sometimes fixed on anglt hrackets Brackets,
attached to chimneys, or ivatt brackets driven into the
masonry. Where arms are not used, pjle brackets (Fig. 3)

mav be employed to S'jpport the insulators.
Brackets are not usually earth wired.

356. The insulation of a conductor may also be effected by Cables,
surrounding it throughout its length with indiarubber, gutta-
percha, or other non-conducting substance. When this
insulating material is protected from injury by a coatincr of
plaited hemp, tape, or wire, it forms what is known as a cable.

A cable may contain one or more insulated conductors.
Cables are employed for : —
(a) Under water lines,
(6) Under ground line 3.
(c) Lines on the surface of the ground.

357. When a cable is to be laid in the water it should be Cnder
strongly protected with a sheathing of steel wires, otherwise ^"'^<^"-
the conductor is hable to be damaged by the anchors of
vessels, or by the motion of the water.

358. A similar kind of cable may be employed for under Under
ground lines, but it is generally more economical to lay a line gJ''3»^°<^-
of iron pipes into which the unprotected insulated conductors

136 CHAPTER XXIII. — EAILWAYS AND TELEGRAPHS.

can be drawn in convenient lengths. Joint boxes should be pro-
vided in the line of pipes at about 100 yards intervals to enable
the lengths of vrires to be connected. After the joints are
made they are covered over with indiarubber tape or gutta-
percha to insulate them. The position of these imder ground
boxes are marked so as to render them accessible when desired
for testing the wires or other purposes.
On the 359. For very rapidly establishing telegraphic communica-

surface tion in the field, a light single core cable u often employed. This
*^^^^^, consists of a stranded steel conductor, moderately insulated
^ ' with indiarubber, and covered with plaited hemp ; thus
considerable tensile strength is obtained with a minimum
weight. The cable is laid out on the surface of the ground
temporarily ; if the communication is required for any length
of time an aerial line is constructed^ and then the cable i?
removed.

Sectiu)), I

:es

136a

Date, 30th May, 1904.

Men.

«•

REMARKS.

Where|i(i contain sufUcienily full and clear information for the Officer, N.-C, Officer or othe)
on toho has to execute the work, to be able to carry on without hesitation.

Eedoubt ivT^nches and redoubt.

of Dunn S
Trencli I, 1{

chalk pit rmvfFse.

HURST CllU

Trench III, M^8\
orchard, ^fe^
on pit, lefP^^^^

Section blockhouse,
uprights bound tofcether
with wire. Loop-holes
;i It. G in. interval,
splayed inwards.

Blockhouse.

JX'ur all. high I ^^
by 2 ft., faced |
by bank. I

,,. , , Redoubt.

1st relief.

-12 1st (lay,
26 Int'antiy
mployeJ.

';//"», nUNN STKKI

DETAIL OF WORKING PARTIES.

Datk, SOlh Mat/, 1004,

CIcartDff and
Trenclilll' ...
Bredhobst Hdr

dlRging trench (iBt relief)
clcarinR hedges in Iron

anddidgingiodsin

bloHinK up lliree isi
demolitiom(encl. win

=■ ■SI .-isis .

BEMAEKS.

1 for all trenches and redoubt. Kect i

a';

TraverserB revelttd

:^ ft

■.al.»ith I E I

irevelttd ott,-- 9 — ^^-^j-

- -7. V V '

Section CommuniLalion Trench.

I fa'nlfy om- f

1 ployed. ■

137

GLOSSARY OF TERMS.

Ihatis. — An obstacle formed of trees or branches of trees.

picketed to the ground, with their points towards the

enemy.
Banquette. — A bank upon which men stand to fire over a

parapet.
Berm. — A small space left between the parapet and excavations

of a work.
Bivouac. — An encampment without tents or huts.
Boinh-proof. — A shelter, proof against the penetration of shells.*
Calibre. — The diameter of the bore of a gun.
Cajoonier. — A small chamber formed in the ditch of a work

projecting from the escarp to give fire down the ditch.
Casemate. — A shell-proof chamber constructed for the accom-
modation of the garrison of a work or position.
Chess. — A plank forming a portion of the flooring of a bridge.
Command. — The vertical height of the crest of a work above

the natural surface of the ground.
Counterscarp. — The slope of the ditch of a work furthest from

the parapet.
Crest. — The intersection of the interior and superior slopes

of a parapet.
Crib-pier. — A support for a bridge formed of layers of baulks

of wood laid alternately at right angles to each other.
Dead ground. — Ground which cannot be covered by the

defenders' fire.
Defilade. — The adjustment of the levels of the crest and interior

portions of a work with a view to obtain cover for the

defenders or to screen them from view.
Derrick. — A single spar held up by four guys, used for lifting

or moving weights.
Embrasure. — A channel through the parapet of a work through

which a gun is fired.

128 GLOSSARY.

Enfilade fire.- -Fire which sweeps a line of troops or defences

from a flank.
Epaulment. — A small parapet to give cover to a gun and

detachment in action.
Escarp. — The slope of a ditch nearest the parapet.
Exterior slope. — The outside slope of a parapet extending

downwaj-ds from the superior slope.
Fascine. — A long bundle of brushwood, tied up tightly, used

for revetting, &c.
Fleche. — A work consisting of two faces, forming a salient

angle towards the enemy.
Fougasse. — A small mine filled with stones w^hich are projected

towards the enemy on the mine being fired. "
Fraise. — A palisade fixed horizontally in a slope.
Gabion. — An open cylinder of brushwood, sheet iron, &c., used

for revetting.
Glacis. — The ground round a work outside the ditch. This is

sometimes made up artificially.
Gorge. — The face of a work furthest from the enemy.
Guy. — A rope fastened to the tip of a spar or frame, to support,

raise or lower it.
Gyn. — A tripod constructed vath three spars, used for raising

weights.
Interior slope. — The inside slope of a parapet (seen in section),

extending from the crest to the banquette.
Keep or Re'duit. — A separate enclosure within another work to

enable the defenders to resist after the outer line of defence

has been carried.
Lunette. — A work consisting of four faces, the two centre ones

forming an obtuse salient, the two side ones affording fire

to the flanks.
Lunette, hlunted. — A work consisting of five faces (otherwise

similar to a lunette).
Machicoulis gallery. — A balcony with a musket-proof parapet

in front, loopholed in the floor, to afford fire in a downward

direction.
Parados. — A traverse to give cover from reverse fire.
Profile. — The section of a parapet at right angles to the crest.
Redan. — A work consisting of two faces, forming a sahent angle

towards the enemy.

GLOSSARY. 139

Tledan, hlmited. — A work consisting of three faces, the centre

one firing to the front, the others to the flanks.
Redoubt. — A field work entirely enclosed by a defensible

parapet.
Relief. — The length of time that men have to work before

being relieved.
Revetment. — Any method of making earth stand at a steeper

slope than the natural slope.
Reverse fire.—¥iie directed on the backs of a line of defenders.
Riband. — A baulk fastened down on each side of a roadway to

keep the chesses in place.
Sap. — A trench formed by constantly extending the end.
Sheers. — Two spars lashed together at the tip and raised to rest

on their butts, which are separated. They are used to lift

and move weights in one plane.
Splinter-'proof. — A shelter, proof against splinters of shell.
Superior slope. — The top of a parapet (seen in section).
Tackle. — Any system of blocks and ropes by which power is

gained at the expense of time {i.e., more power — less

speed).
Tambour. — A projecting chamber or stockaded enclosure, con-
structed so as to flank the walls of a building.
Terreplein. — The surface of the ground inside a work.
Trace. — The outline of a work in plan.
Traverse. — A bank of earth erected to give cover against

enfilade fire, and to localise the bursts of shells.
Wattle. — Continuous brushwood hurdle work.

140

IND

EX.

PAGE

Abatis

42, 137

Cables

135

Alarms, automatic

. . 47

Camping arrangements . .

Ammunition recesse

53 .. ..37

Camps, defence of . .

wagon

s, cover for . . 37

Canvas, Willesden

Anchors

Capstan

107

„ makeshift

. . 65

Casks, buoyancy of

105

Artillery, cover for

. . 37

„ shnging

„ field .

..7,95

„ table of

105

„ fire

Chain crane

102

,107

„ heavy .

8, 66, 96

„ strength of . .

102

„ projectilef

3, penetration

Chairs

130

of .

Charges, cordite . .

Attacks, night

. . 49

„ guncotton

'79

119

Automatic alarms .

.. 47

„ powder . . 81, 9
„ simultaneous
Cheddit3

2,95,

118

Balancing parapet and excavation 14

Choker

Ballast

. . 130

Clearing the foregroimd , .

Barricades . .

Collin's rule

105

Belaying . .

Command . .

137

Berkefeld filter .

. . 73

Communications, temporary

Bivouacs . .

73, 137

Co:- due -ors, telegraph

133

Blockhouses

Cooking

Blocks and tackle . .

107, 139

Cordage

101

Boat patrols

. . 66

Cordite

. .7

9,82

Boats

. . 62

,, charges

119

„ buoyancy of

. . 63

Corduroy roads

Boning and leveUin

g .. ..126

Cover for artillery . .

Booming out

. . 65

„ head . .

Brackets for telegra

phs .. .. 135

,, overhead . .

Breastworks of logs

„ trenches

Bridges, cantilever

. . 109

Crane chain

102

107

„ demolition

of . . SO, 93

Crib work . .

137

floating .

Cutting brushwood

120

flying

,, tools

,, frame

110

Cuttings

„ railway, de

fence of . . 46

„ sites of .

Bridging expedients

J .. ..61

Defence of buildings

Brushwood . .

. . 18, 25, 124

„ localities

„ revetme

nt .. .. 23

„ villages

Buildings, defence (

Df .. ..29

Demohtions, general rules for

. .

„ demoUtic

mof .. ..26.93

„ hasty — ^vith explo-

Buoyancy of boats

sives

., of casks

. . 105

„ „ without

ex-

„ of timbe

r .. ..106

plosives..

INDEX. 141

PAGE

Demolitions, table of charges 118^ 119

Formula for average yield of

Depots for raihvay material

. 132

stream . . . . 70

Derricks

. 108

„ buoyancy of casks 105

Detonators . .

„ cantilever bridge 104

Diagonal lashing . .

„ contents of round

Double lock bridge

. 110

logs . . . . 106

Double-manning tools

„ hasty demoHtions

Drainage of trenches

.37,40

118, 119

Dynamite . .

. 82

„ power of tackles . . 107

„ charges . .

„ rectangular beams 103
„ round spars . . 103
>, strength of cordage 101

Earth, slope of . .

. 17

„ suspension bridges IIS

Earthworks

. 31

„ velocity of stream 56

Embankments

. 27

Fortification, object of . . . . 5

Entanglements, tree

,, principles of . . 5

„ wire

Fougasse 43,138

Entrances to redoubts

.40,48

Fcur-legged trestles . . . . 61

Epaulments

37, 138

I'raises . . . . . , . . 43

Execution of work

. 14

Frame bridges no

Explosives carried in the field .

.13,78

Fuzes 85,86

„ substitutes for . . . . 87

Fascines . . 19, 23, 51, 120, 1

25, 138

Gabions 20, 23, 138

Faults in telegraph line . .

. 99

„ Jones' . . . . . . 22

Ferries

. 66

Garrison of redoubts . . . . 39

Field geometry

Gauge of railways . . . . . . 128

„ guns . . . . 7, 58, 95, 102, 119

Geometry, field . . . . . . 10

„ howitzers

.8,102

Glossary of terms 137

„ kitchens

. 68

Guncotton . . . . . . . . 79

„ level

. 127

charges .. 80,119

,, ovens

. 69

Guns, destruction of . . 95, 119

„ redoubts

. 38

„ field . . . . 7, 58, 95, 102, 119

Filtration

. 72

„ siege . . . . 8, 58, 95, 102, 119

Fire, artillery

7,8,9

>, spring 47

„ natures of . .

Guys . . . . 108, 109, 138

„ rifle

. 6,9

Gyns 109,138

„ trenches

. 33

Fishplates . .

. 129

Hasty demolitions, formula for 118, 119

Flares

. 47

,, „ with explosives 78

Floating bridges . .

. 62

„ „ without explo-

Flying bridges

. 66

sives . . 93

Fords

. 67

Head cover . . . . . . 34

Foreground, clearing the. .

Hedges 25,27

„ illuminati:n of

. 47

Height of line of fire . . . . 6

Forming cuts

. 66

Houses, demolition of . . . . 90

» up

Howitzers, field .. .. ..8,102

142

INDEX.

PAGE

Hurdles . . 22, 23, 74, 75, 120. 125

Penetration of artillery projectiles 7

Huts

. .75, 77

rife bullets

„ demolition of

.. 90

Pickets

Illumination

..44,47

Platforms, temporary
Poles telegraph ..

. 132
. 134

Insulators . .

.. 134

Posts, defence cf . .

Intrenching tools . .

..12,13

Powder

Inundations

„ charges

31, 118

Invisibility . .

..32,39

hose

Jones' gabions

.. 22

„ mealed
Power of tackles . .

. 87
. 107

Kettles, service

..66,68

Precautions with explcsvcs

. 87

Keys

.. 129

Primers

79,80

Knots

.. 52

Principles of fortification

Profiling . .

. 15

Lashings . . . . . . 5

4, 108, 110

Proof thickness of materials

rack

.. 53

Protected look-out

. 36

Latrines

..40.69

Pumps

. 72

Level, field

. . 127

Purifying water . . . . ,_, 72

Levelling . .

.. 126

Line of fire, height of

Rack lashing

. 53

Localities, defence of

Rafting

. 66

Log breastworks . .

Rafts

64, 66

Log huts

Rails, destruction cf . . 94 119

Lookout, protected

„ types of

129

Loopholes . . . . 2Q

30, 34, 48

Railwa;/ bridges . .

132

„ „ demoHtioa ot ,

Makeshift, anchors

Railways 93, 128

Materials

„ demolition of . . 93, 96. 119

„ proof thickness of

„ repair of

131

Mats, straw

Randing

Mechanical alarms
Mousing

.. 47
.. 55

Ranges of various weapons
Rectifiers ,.

8
81

Redoubts . .

31,38

Netting, wire
Night attacks

24
.. 49

„ high command . .
„ low command . .

39
39

Object of fortification

Rehef

139

Obstacles

..41,49

Revetments

„ passage of

.. 44

Rifle fire

6,9

Outposts, cover for

.. 49

„ rests fixed . .

Ovens, field

.. 69

Roads

123

Overhead cover . .

.. 35

„ corduroy . .

„ gradients of

123

Pairing

.. 21

„ lajdng out

123

Palisades . .

„ metalled . .

124

Panels, straw

>. repair of . ,

15^5

Parties, working . .

„ temporary

rNDEX.

143'

PAGE

lAOE

Sandbags . .

. 28, 35, 120

Telegraphs, destruction of

. . 98, 119

Sangars

Telephones . .

.. 133

Savage warfare

.. 46

Temporary communications

Screens

.. 30

Terms, glossary of

.. 137

Seizing

Thatching

.. 76

Service kettles

..66,68

Thickness, proof of materials

Sewing

.. 21

Timber, buoyancy

.. 106

Siieers

108, 139

„ destruction of . .

.. 91

Simultaneous charges

.. 87

„ felling

.. 18

Single-lock bridge . .

.. 110

„ revetment

Sinking wells

.. 71

„ weight of

.. 106

Siting of redoubts. .

Tools, cutting

13, 120

„ trenches

„ double-manning . .

.. 16

Sleepers

. . 130

„ intrenching..

. . 12, 13

Slewing

.. 22

„ use of

.. 12

Slinging; ca«ks

.. 53

Trace of redoubt . .

Slopes, description of

Traverses . .

..36,40

Sods

17, 24, 120

Tree entanglements

.. 42

Spars . . 59, 103,

107, 108, HI

Trenails

.. 130

Spifclocking . .

.. 123

Trenches . .

.. 31

Sphnter proofs

36, 40, 139

„ communication

.. 37

Springs

..71,72

„ cover

.. 37

Stations, railway, defence

cf . . 46

„ drainage of

..37,40

Stays and struts . .

.. 135

jj nre

Stockades . .

. . 29, 92

„ siting

Stones, parapets of

.. 17

Trestle bridges

.. 59

Straw panels

.. 77

„ fourlegged . .

.. 61

;, mats

„ tripod

.. 60

Stream, average yield of .

.. 70

Tunnels, demolition of . .

„ measurement of b

•eadth H

„ velocity . .

.. 56

Use of spars

.. 107

Strength of bridges

58, 102, 111

„ tools

„ chain . .

.. 102

„ cordage

.. 101

Velocity of stream

.. 56

wire ..

.. lOl

Villages, defence of

.. 48

„ „ rope

.. lOl

Suspension bridges

.. 113

Swuiging bridge . .

.. 66

Waling

.. 21

Walls, defence of . .

.. 2Q

Tackles

107, 139

demohtion of . . 90,

118, 119

„ power of . .

.. 107

Warfare, savage . .

.. 46

Tambour . .

. . 139

Warping . .

.. m

Tamping . .

78, 84, 88

Water, filtration of

.. 72

Tasks

„ supply

.. 70

„ method of executing . . 16

,, „ for railways

. . 133

Tracing

.. 15

„ weight of . .

70, ].04

Telegraphs

98, 133

Wattle and daub . .

.. 77

144

INDEX.

PAGE

T.\C,K

Weapons, rano:es of

Wire rope, strength of , .

. . 101

Wells

..71,72

Wires, earth

.. 134

Willesden canvas . .

.. 24

Withes

paper ..

.. 22

Woofls, defence of

.. 28

Winch

.. 107

Working party tabic

. . 120

Wire entanglements

.. 42

„ „ detail of . .

.. 136a

„ netting

.. 24

„ parties, detailing

^ 14

(Wt. 11464 35,000 9 ] 05— fl & S 52S9)

P. 04
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