_Attentions in making Fascines_—The bands must be from 10 to 12 inches
asunder, of birch, hazle, or other pliant wood, well twisted. The
fascines must be drawn close with a choke rope, previous to being tied.
In laying the wood to form the fascines, the shortest and smallest
pieces should be laid inside. Three men are usually employed at each
trestle, with two to collect the stuff.
In general a saucisson of 18 feet may be finished at each trestle in
half an hour.
Birch and fir are the bell woods for this work.
Fascines are sometimes bent so as to coincide with the angles of the
battery. The Prussians double some of the fascine stuff, so as to make
a loop at the end of the fascine, which being laid over one another at
the corners, and a stake driven through the loops, are very strong.
_FIRE SHIP._—_Proportion of combustible Stores for a Fire Ship of 150
Tons._
Nᵒ.
Fire barrels, filled with composition 8
Iron chambers, to blow open the ports 12
Composition for priming, barrels 3½
Quick, match, ” 1
Curtains, dipped 48
Reeds, long, single dipped 150
” short, { double dipped 75
{ single dipped 75
Bavins, single dipped 250
The fire barrels are about 2 feet 4 inches high, and 1 foot 6 inches
diameter. Each barrel must have four holes of about 6 inches square
cut in its sides; and these holes must have a square piece of canvass
nailed over them quite close. They are then filled with the same
composition as for carcasses, and 4 plugs of about 1 inch diameter and
3 inches long, and well greased, are thrust into the top, and then left
to dry. When dry, these plugs are taken out, and the holes driven with
fuze composition, and quick match at the top; which goes from one hole
to the other: after this the top is smeared over with mealed powder
mixt up with spirits of wine. When dry again, a sheet or two of brown
paper is laid over the top, and then one of the canvass covers, which
is made secure by the upper hoop of the barrel.
_Composition for dipping Reeds, Bavins, and Curtains._
lbs.
Rosin 120
Coarse sulphur 90
Swedish pitch 60
Tallow 6
Mealed powder 12
This proportion will dip about 100 reeds and 25 bavins.
Each curtain contains 1 square yard of barras.
Each cover for fire barrels 1 do. of sacking.
Immediately that the curtains, covers, &c. are dipped, they are to be
strewed over with fine brimstone, before the composition grows cold.
The iron chambers, for blowing open the ports, hold from 9 to 11 ounces
of powder. They are fixed in such a manner as to prevent their recoil,
and to ensure the ports being blown open. The vents are generally
corked up, and covered with a piece of barras, till required to be
primed.
_To fit out a Fire Ship._—The whole breadth of the fire room is to be
divided into 9 parts, and troughs laid the whole length of the room.
Cross troughs, of communication are laid between them, about 20 in each
row, perpendicular to the long troughs. These troughs are usually
4 inches wide, and 4 deep. There are two fire trunks and two fire
scuttles on each side, under which the eight fire barrels are to be
placed.
The reeds and bavins are to be tied down in the troughs. The curtains
are to be nailed up to the beams, equally through the fire room. The
ship is not to be primed when fitted out, but only when intended to be
fired.
_To Prime._
_Composition for Priming._
Saltpetre pulverized 22 lbs. 8 oz.
Rosin 2 11
Sulphur 18 —
Mealed powder 45 —
Linseed oil 1 pint.
All the reeds and bavins are to be taken up, and a little of the above
composition sprinkled in the bottom of the troughs; the reeds, &c. to
be then gently tied down again. Quick match of 6 or 8 threads doubled
must be laid along on the tops of all the reeds &c. and the priming
composition strewed over it, and over all the fire room. The covers of
all the fire barrels must be cut open, and made to hang down on the
sides of the barrels. Leaders of strong quick match must be laid from
the reeds to the barrels and to the chambers; and must be tied down to
the vents to insure its not falling off. Strong leaders of quick match;
4 or 5 times doubled, must be laid from the reeds to the sally ports;
and the sally ports must be connected by quick match, that the whole
may take fire at once.
The following method is now adopted of producing an external fire, in
addition to the internal fire, before gained by the fire room.
Fire boxes filled with the carcass composition, are distributed in the
following manner, in a ship of three masts:
1 Suspended from each of the catheads and davits,
on each side the bow 4
8 Slung across the bowsprit 8
4 Across each of the outriggers abaft 8
2 From the graplins of each of the lower yardarms 12
1 From the deadeyes on each side of the three round tops 6
1 From the middle of the inside of the main, fore,
and mizen shrouds 6
——
44
The boxes are suspended by chains and hooks, and those slung across
the bowsprit and outriggers, are fixed by staples. The two inner ones
are laid with leaders of quick match, which fire instantly, or with
portfires, which burn a given time; they communicate with the outer
ones by reeds, which are tied down on the bowsprit and outriggers. The
boxes hanging from the deadeyes and shrouds, are fired by curtains
suspended from the shrouds, the lower one of which hangs immediately
over one of the large fire barrels. The two boxes on each yardarm are
hung one over the other; the upper one having a leader of quick match
carried along the yard from the shrouds; and in burning will no doubt
fire the lower one. Besides the boxes, there are fire barrels arranged
as follows; 2 half barrels on the forecastle; 2 abaft the main deck,
and 4 on the main deck; 2 in each roundtop, placed against the masts;
and 4 large fire barrels under fire trunks, to convey fire to the
curtains on the shrouds. All these fire barrels and boxes are to be
fired by separate leaders of quick match or portfire, in order that
any part of the ship may be fired to cover its approach by the smoke;
and the remaining part instantaneously upon quitting the ship. It has
been found by experiment, that two men with lighted portfires can set
fire to the whole of the leaders on the deck, bowsprit, catheads,
outriggers, &c. in less than a minute; therefore the risk of trusting
to one main leader to the whole, may be avoided.
The leaders are laid in painted canvass hose made for the purpose.
_FLINTS_—are usually packed in half barrels.
Weight.
Qrs. lbs.
{Musquet, 2000 2 14
One half barrel contains {Carbine, 3000 2 10
{Pistol, 4000 2 15
The most transparent and free from veins are esteemed the best flints.
cwts. qrs.
28 kegs of musquet flints take 18 0 in tonnage
10 kegs of pistol ” ” 3 2 ”
_FORTIFICATION.—Practical Maxims in building Field Works._
1st. The spot on which works are to be constructed should determine
their figure; nor should any attention be paid to preserve a regular
form which does not occupy the ground to advantage.
2d. Every line must be so disposed, that the slope of hills all around
even to the very bottom, be open to the small arms of the garrison; and
every part should be discoverable to the distance of at least 500 paces.
3d. Works thrown up for the defence of a defile, should always be
within musquet shot of it, which must not be more than 200 yards.
4th. The best defence in works that are flanked, or where one side is
defended by the fire of another, is that formed by right angles.
5th. A salient angle should never be less than 60, and a re-entering
angle than 90 degrees; nor greater than 120 degrees.
6th. The entrance to the work should always be made in the part least
exposed to attack, and if possible in a re-entering angle.
7th Endeavor to present, if possible, a larger front to the enemy than
he can occupy in making the attack.
8th. Avoid all ground commanded by an eminence, either in front, flank,
or rear.
9th. Never leave the rear of a work so exposed that the enemy may turn
it.
10th. Always make the angles of a work in the directions least exposed
to attacks, and consequently always present a front to the most exposed.
11th. The garrison should never be drawn up more than two deep; and an
ordinary pace of two feet is usually allowed for each file, and from 6
to 8 paces from each piece of ordnance.
12th. If a work is so large as to be defended by a battalion or two, a
reserve should be allowed of about one sixth of the number.
13th. The space within a work should always be sufficient for the men
to move and lie down. Every soldier will require at least 18 square
feet, and every field gun at least 216 square feet.
14th. Provided the line is not made too extensive, the more inward
space there is the better.
15th. A parapet to resist cannon shot should never be less than 12 feet
thick; and for musquet shot not less than 6 feet.
16th. The height of the parapet must be regulated by the situation of
the work, and of the adjoining ground; with this consideration, that
its height above the banquette does not exceed 4½ feet.
17th. The depth and breadth of the ditch must be regulated by the
quantity of earth required, for the parapet and banquette.
18th. A tete de pont, or work to cover the embarkation of troops, or
the passage of a river, should, if possible, be made where the line of
the river or coast forms a kind of re-entering angle; that the flanks
of the corps, as well as those of the works, may be covered.
_To carry on the Work._—The number of workmen must be proportioned to
the time allotted for carrying on the work, the quantity of labour,
and the number of hands capable of being employed at the same time.
When the ditches are broad, the workmen may be posted in two rows; but
if narrow, only in one. In the first case, the earth will be thrown
by those who are on the outward edge of the ditch to the second row,
and by them upon the parapet; for which reason the second row, to
keep pace with the first, ought to be twice as numerous. The workmen
should never be placed nearer than 2 paces, or 4 feet, from each other;
and two men with shovels should be preceded by one with a pickaxe. If
more than usual expedition be required, one man with a wheel barrow,
or basket, may be added to six or eight with shovels. Another row of
workmen should also be placed upon the parapet, to spread the earth and
beat it down, as it is thrown up.
In fixing the fascines, three men will be sufficient for every 24 feet
of the work, who should be provided with two mallets, a saw, and a
handbill, or hatchet.
In order to form some idea of the time in which a field work may be
completed, compute the number of cubic feet of earth to be excavated,
thus; multiply half the sum of the breadth of the ditch at top and at
bottom, by the depth, for the number of square feet in the profile;
and this multiplied by the distance between the workmen in feet, will
give the number of cubic feet each man has to dig: or being multiplied
by the length of the ditch, gives the cubic contents of the ditch.
Now, one man is supposed to be able to move 216 cubic feet of earth
in a day, during the summer; but this is not always the case. If a
field work be completed in 24 hours, it will be as much as the most
diligent workmen are capable of. This time is generally allowed for
the formation of a weak profile; 48 hours for that of a stronger, with
a revetement of fascines; and 72 for the strongest.
The different slopes for the works must depend upon the nature of the
soil, and the materials of which the work is composed. The interior
slope of the parapet, though it be fascined, should be ⅙ of its height;
exterior about ⅔ its height. The slope of the banquette equal to its
height. The slope of the scarpe or counterscarpe of the ditch, should
be from half its height to its full height, according to the soil. The
superior slope of the parapet must entirely depend upon the situation
of the work, and that of the surrounding country. The interior slope of
the parapet is generally lined with fascines, to keep up the earth; but
it is not absolutely necessary to fascine the exterior slope, if the
soil be pretty stiff. The embrazures are generally made 20 inches wide
on the inside, and 9 feet on the outside; they must always be lined
with something to retain the earth; turf is generally preferred, as
fascines are so apt to take fire.
The manner of making the materials for field works, may be seen under
the heads _Fascines_, _Gabions_, _Hurdles_, &c. and the manner of
estimating the quantity of materials for works of this kind, may be
seen under the word _Battery_.
_Fortification—Permanent._
A _parapet_, to resist cannon, should never be less than 18 feet thick
in earth, and 8 or 9 in masonry. A wall need only be two feet thick
in masonry, to resist musquetry. The parapet should always be 4½ feet
above the banquette, and 7½ or 8 feet above the rampart, or terre plein.
The _Rampart_ should always be sufficiently wide to allow for the
platform, and for two carriages passing each other; about 9 fathoms
at top. A parapet of earth, though it takes more room, is always
preferable to one of masonry, when it can be raised; though the only
objection to the masonry is the number of splinters it produces.
Entire _Revetements_ of masonry are not advantageous for the same
reason. The masonry of revetements should not be so high as to be seen
or battered from a distance: earth parapets are battered in vain, as
the earth forms a natural slope.
The best _Escarpe_ is made of masonry, either in wet or dry ditches, be
the earthen one ever so well fraized or palissaded. The earthen one may
be stormed without making a breach. The escarpe should be 30 or 35 feet
high.
The _Counterscarpe_ should also be of masonry, and not less than 12
feet high. The inconveniences of an earth or low counterscarpe, are
the impossibility of defending to the last the covert way; as the
enemy may descend into the ditch, and again mount the covert way, and
so get in the rear of the traverses. The enemy may find his way along
the natural slope of an earth counterscarpe, and is not delayed by a
tedious operation of getting into the ditch. Besides, the natural slope
of the end of an earth traverse prevents its effectually covering the
covert way.
_Ditches_ are generally 15 or 18 toises wide. Dry ditches are always
preferable to wet ones, on account of the shelter they afford the
troops, and the ready communication with the outworks, without the
constant trouble and danger of bridges.
The _Covert way_ should be 5 toises wide; less would crowd the troops,
and more would allow room for the enemy to erect batteries in it.
The whole of the glacis should be seen, not only from the crest of the
parapet, but from the embrazures in the parapet.
The _Tenaile_, must not be so high as to prevent the flank guns in one
bastion seeing the breach that may be made in the collateral one.
_Ravelins_ are best without flanks; their faces directed to 10 toises
from the shoulders of the bastions.
The crest of the parapet of the body of the place should be 8 feet
above the crest of the glacis, to command it across a ditch of 15 or 20
toises.
The crest of the parapet of the ravelin is 3 feet lower than that
of the body of the place, in order that it may be more effectually
commanded from the place; and therefore to enable the parapet of the
ravelin to command its own glacis, the ditch is only made 10 toises,
and this glacis is a foot lower than that of the body of the place.
There must be an equilibrium of defence established through every
front of a fortified place; for it will be needless to strengthen any
particular front, if the others from their weakness be left exposed.
The following remarks may enable an observer to appreciate the value of
particular works, in the proper application and arrangement of which
that equilibrium consists.
_Intrenchments_ within the works add much to their defence. In
large bastions with obtuse flanked angles, the best intrenchment is
formed of the front of a fortification, or of two demi bastions and
a curtain, connecting the angles formed by the flank and curtain. If
this intrenchment be advanced to the shoulders of the bastion, so as
to include its flanks, as is often the case, it will be subject to be
taken in the rear, by the fire from the counter batteries opposed to
the flanks. But in bastions with acute flanked angles, which do not
afford sufficient space for this kind of intrenchment, Cormontaigne
proposes one in the form of a cavalier, whose faces and flanks are
parallel to those of the bastion. The first kind of intrenchment does
not operate in the defence of the place, till after the passage of the
ditch; till which time it remains entire, and then capable of a very
great defence. The second kind becomes a support to the bastion from
the first commencement of the siege; but it is therefore subject to
have its defences destroyed at a distance. Nor is its defence equal to
that of the other form.
_Counterguards_ should possess the three following properties: 1st.
They must cover effectually the principal work before which they are
placed; at least that part of it, which can be battered in breach. 2d.
They must be lower than the work which they cover; but not so low as to
permit its revetement to be seen. 3d. They must be so narrow as not to
afford room for the besiegers to erect batteries in them, against the
work which they cover, and therefore not leave the besiegers a choice
of positions. The counterguards in Coehorn’s system are only of earth,
through which it is necessary to make an opening, before the capital
work can be battered.
_Horn_ or _Crown Works_, unless to occupy some important point, to
strengthen some weak side, or to afford more room for a confined
garrison, are rather a weak than a strong arm to a place. This is
particularly the case when they are constructed with smaller, and
consequently weaker fronts, than that part of the body of the place
which they cover; as they facilitate, when taken, the approaches to
the body of the place. This is remedied by constructing their fronts
of the same strength as the front or fronts which they cover. They
also facilitate the taking of the place, by exposing the revetement
of the work on which their branches are directed, to be battered in
breach, along the ditches of those branches. This is a great evil,
even to an outwork, but is of serious consequence if they rest upon
the body of the place. This defect has been remedied by placing these
works altogether outside of the covert way, and allowing their ditch no
communication with those in the rear. In this case their gorge must be
made very secure to prevent its being turned.
An _Advanced Covert_ way, is esteemed amongst the best means of adding
to the defence of places. Besides the advantages common to the usual
covert way, it has many peculiar to itself. It however seems necessary
to ensure to it the many advantages of which it is susceptible,
(beside being properly palissaded,) that it should be secured in the
rear by a wet ditch, as the only means of giving it an inaccessible
counterscarpe, and at the same time keeping it under the fire of the
musquetry of the place. This kind of covert way is generally supported
by redoubts upon the capitals of the bastions and ravelins; which from
their position cannot mask the fire of the place; and being mounted
with artillery, oblige the besiegers to commence their attack at a
great distance, and very much to extend their operations; and as their
establishment upon this covert way must effectually mask the fire of
their first batteries, it must greatly increase their labour. The
retreat from these redoubts must be secured by an underground passage.
_Countermines_ are undoubtedly one of the first means of strengthening
places. For this article we refer to the word _Mines_.
_Detached Redoubts_, when circumstances of situation favour them, are
employed with great success. They are usually detached and totally
unconnected with any of the works of the place, by any covert way or
other aboveground work; and have for objects, either the opposing an
additional obstacle to the besiegers at the point they occupy, or
the rendering the adjoining fronts inaccessible, by an enfilade or
reverse fire upon the approaches. They also afford at their gorge, a
most excellent rendezvous and retreat for sorties; upon the level of
the country, and without the difficulty of filing troops through the
barrier of a covert way.
But in order to insure to the detached work or works, all these
advantages, it is necessary that they should be either totally
inaccessible to the besiegers, by reason of the natural difficulties
of their situation, as in an inundation, morass, &c. or be made secure
by art, from being taken by storm, and only attackable by regular
approaches. They should be under cover of the fire of the place; but
if their distance be too great for that, an intermediate work must be
established to give them support. Their best form is that of a bastion
with retired flanks; and a strong system of countermines the most
effectual way of prolonging their resistance.
_General Remarks._—The larger the flanked angles of works, the more
direct will be their fire, and that of their covert way, upon the
approaches; the greater extent will they oblige the besiegers to occupy
in their parallels and batteries; and the more will they oblige the
besiegers to expose themselves to the fire of the fronts collateral to
the one attacked. Faces of works directed to inaccessible situations,
such as rivers, lakes, &c. from whence they cannot be enfiladed by
ricochet batteries, add greatly to the strength of a front.
If the flanked angle of a ravelin be so advanced as to see in reverse
any battery erected upon the crest of the glacis, or in the covert
way of the bastions, it will increase the strength of that front;
because it will oblige the besiegers to gain possession of the ravelin,
before they can make any lodgement, from which they can batter the
bastions. This is the case in Cormontaigne’s system: and a place thus
fortified, obliges the besiegers to attack and gain two ravelins, to
get at the bastion between them. Beside, if this system be applied to
a right line, or to a polygon of many sides, the prolongations of the
faces of the bastions, will be intercepted by the flanked angle of
the ravelins, and consequently make the establishment of enfilading
batteries against them very difficult. A work which admits of a breach
being made in it (particularly the body of the place) at a distance,
very much facilitates its being taken. The ditch of the ravelin affords
an opening through which the besiegers may make a breach in the face
of the bastion, from the glacis, opposite the flanked angle of the
ravelin, and is therefore subject to this defect. A counterguard before
the bastion, lessens this evil, by transferring the breach from the
body of the place to the ravelin; but it requires a counterguard also
before the ravelin, effectually to cure it. A crown or horn work also
produces this evil; its remedy was given, in speaking of those works.
The direction of the flanks or faces of a work is not so material
as relating to the fire of artillery, as to that of musquetry; for
artillery is never fired without being pointed, but musquetry is fired
mechanically, and perpendicular to the parapet, without much attention
to the object to be struck.
A work in the neighbourhood of a height must be defiladed[7] from
that height, that is, instead of being built upon a horizontal plane,
it must be erected upon an imaginary inclined plane, passing from
somewhere in the interior of that work, over the most commanding points
of the height: and every part of the works must bear the same relation
to this inclined plane, that they would do, to a horizontal plane in a
level country.
A work is not therefore always to be condemned, because it is in the
neighbourhood of a height; for if it be properly defiladed from that
height, it will receive a great advantage over the approaches of the
besiegers, carried on down an inclined plane towards it. But a work
to be properly constructed in the neighbourhood of heights, must
not uniformly preserve the same distance from those heights, unless
their summits be all upon the same level; but must approach them at
their lowest parts, and recede from them as they rise; thus will the
necessary plane of defilement preserve nearly the same degree of
obliquity throughout.
_The Dimensions in the following Table of Vauban, are thus applied_:
The _Fort_ is mostly for squares.
The _Little_ for citadels, commonly pentagons.
The _Mean_ for all fortifications from the hexagon and upwards.
The _Great_ is seldom used but in irregular fortifications, and
particularly on rivers.
[7] The compiler must here apologize for coining the word _defiladed_,
which he is obliged to do, never having seen this subject treated of
in English. But the French use the word _defile_ in a contrary sense
to _enfile_; and as we admit the words enfilade and enfiladed from the
latter, we cannot refuse the terms defilade and defiladed from the
former.
_Principal Dimensions of Fortifications, according to_ VAUBAN.
+-----------------+-------+-------------+--------+----------+
| |Side of| Length of |Faces of|Capital of|
| |Polygon|Perpendicular|Bastions|Ravelins |
+-----------------+-------+-------------+--------+----------+
| Forts. | 80 | 10 | 22 | 25 |
| | 90 | 12 | 25 | 28 |
| | 100 | 12½ | 28 | 30 |
| | 110 | 14 | 30 | 35 |
| | 120 | 15 | 33 | 38 |
| | 130 | 16 | 35 | 40 |
| | | | | |
| Little | 140 | 20 | 40 | 45 |
| Fortification. | 150 | 21 | 42 | 50 |
| | 160 | 23 | 45 | 50 |
| | 170 | 25 | 47 | 52 |
| | | | | |
| Mean. | 180 | 30 | 50 | 55 |
| | 190 | 31 | 53 | 55 |
| | | | | |
| Great. | 200 | 25 | 55 | 60 |
| | 260 | 22 | 60 | 50 |
+-----------------+-------+-------------+--------+----------+
_Dimensions of Walls and their Counterforts, from 10 to 50 Feet high,
having a Slope of ⅕ their Height._
+--------------------------------++-----------------------------+
| Wall. || Counterforts. |
+--------+-----------+-----------++--------+---------+----------+
| | | ||Distance| | |
| | Thickness |Thickness ||between | | |
|Height. | at Top. |at Bottom. || them. | Breadth.| Length. |
+--------+-----------+-----------++--------+---------+----------+
|Feet. |Feet. Inch.|Feet. Inch.|| Feet. |Feet. In.| Feet. In.|
|10 | 4 0 | 6 0 || 8 | 2 8 | 4 — |
|15 | 4 3 | 7 3 || 10 | 3 4 | 5 — |
|20 | 4 6 | 8 6 || 12 | 4 0 | 6 — |
|25 | 4 9 | 9 9 || 14 | 4 8 | 7 — |
|30 | 5 0 | 11 0 || 16 | 5 4 | 8 — |
|35 | 5 3 | 12 3 || 18 | 6 0 | 9 — |
|40 | 5 6 | 13 6 || 20 | 6 8 | 10 — |
|45 | 5 9 | 14 9 || 22 | 7 4 | 11 — |
|50 | 6 0 | 16 0 || 24 | 8 0 | 12 — |
+--------+-----------+-----------++--------+---------+----------+
The heights in the above table are taken only from the bottom of the
ditch, and do not include the foundations.
When the rampart is partly walled and partly turfed; then ⅕ of the
height of the turfed part must be added to the breadth of the wall at
the top given in the table.
The bases of all inward slopes of earth should be equal to their
height, if not more.
The bases of all outward slopes of earth ⅔ of their height.
The superior slopes of all parapets ⅙ of their breadth.
The slope of all walls, or revetement ⅕ of their height.
Though the above principles given for the erection of field works may
assist an officer’s recollection who may be employed on that duty,
the memorandums given respecting _permanent_ fortification pretend
to no such object: but may serve to remind an officer, if he should
visit a fortification, of its essential requisites; and may assist his
observations in passing round the works.
_FUZES.—Composition._
Saltpetre 3 lbs. 4 oz.
Sulphur 1 —
Mealed powder 2 12
+--------+------------------------+-------------------------+------+
|Nature. | Fuze Diameter. | Composition. |Drove |
| +--------+-------+-------+---------+-------+-------+by one|
| | below |at the | at the|Diameter.|Length.|Time it|man in|
| |the cup.|bottom.| cup. | | |burns. |1 day.|
+--------+--------+-------+-------+---------+-------+-------+------+
|Inches. | Inch. |Inches.|Inches.| Inch. | Inch. | ″ | Nᵒ. |
| 13 | 2.1 | 1.575 | 2.49 | .5 | 8.4 | 35 | 25 |
| 10 | 1.8 | 1.35 | 2.13 | .438 | 7.2 | 33 | 25 |
| 8 | 1.3 | 1.25 | 1.78 | .375 | 6.37 | 29 | 30 |
| 5½ | 1.1 | .825 | 1.3 | .275 | 4.4 | 18 | 50 |
| 4⅖ | 1.0 | .75 | 1.18 | .25 | 3.5 | 15 | 700 |
|Grenades| 0.8 | .6 | .9 | .2 | 2.25 | | 1000 |
+--------+--------+-------+-------+---------+-------+-------+------+
Diameter inside the cup is 3 diameters of the bore.
Depth of the cup 1½ do.
Thickness of wood at bottom of the bore, 2 diameters.
_To find the Length of Fuzes for any Range._
The 13 and 10 inch fuzes of the same length burn so nearly equal, that
one common length answers both, as do the 8 inch, 5½ and 4⅖. Therefore,
to find the length of fuze for any range, multiply the time of flight
by .22 for the 13 and 10 inch, and by .24 for the 8, 5½, and 4⅖; which
is the decimal part of an inch a fuze burns in a second. Fuzes are
thought to keep better by being painted; and for field service, are
often marked off by black lines into seconds and ½ seconds.
_GABIONS._—Small gabions of 3 feet high, and 2 feet diameter, are made
with least trouble, and are easiest carried. The pickets for them must
be 1½ or 2 inches thick, and 4 feet long. Large gabions are 6 feet
high, and 3 feet in diameter; and require two men to carry them. The
smallest gabions or baskets are formed of pickets, 1 inch in thickness,
and 1 foot long: they are 12 inches in diameter at top, and 10 at
bottom. The small gabions have 7 or 8 pickets, the large ones 9 or 10.
_To make them._—The pickets are first to be fixed in the ground in a
circle, the size of the bottom of the intended gabion; then a few twigs
are to be wove through the upper ends, to keep them from flying out;
afterwards the work must be begun at the bottom and continued upwards;
and the whole being well driven down with a mallet, the edges must be
secured by twigs, wattled up and down. The twigs of willow, birch,
hazle, alder, poplar, and beech are proper for this purpose. The top
of the gabion must be made very even, because that becomes the bottom
when finished. Four men are usually employed on each gabion, with a
billhook, a mallet, a spade, and two axes. Two collect the wood, while
the other two form the gabion. A 3 foot gabion ought to be made in half
an hour.
_GIN Triangle._—Length of arms of the gin 16 feet 4½ inches. Roller,
6 feet long. Tackle fall, 78 feet of 3 inch white rope. Sling, 6 inch
white rope.
For the different exercises of the gin, see the word _Exercise_.
_GRAVITY.—Table of the Specific Gravity of several Solid and Fluid
Bodies._
Platina 23400 Nitre 1900
Fine gold 19640 Ivory 1825
Standard gold 18888 Brimstone 1810
Quicksilver 11325 Solid gunpowder 1745
Fine silver 11091 Sand 1520
Standard silver 10535 Coal 1250
Copper 9000 Boxwood 1030
Copper halfpence 8915 Sea water 1030
Gun metal 8784 Common water 1000
Cast brass 8000 Oak 925
Steel 7850 Gunpowder, close stacken 937
Iron 7645 ” in loose heap 836
Cast iron 7425 Ash 800
Tin 7320 Maple 755
Crystal glass 3150 Elm 600
Marble 2700 Fir 550
Common green glass 2600 Charcoal
Flint 2570 Cork 240
Common stone 2520 Air 1.232
Clay 2160
Brick 2000
Common earth 1984
The several sorts of wood are supposed dry.
This table also contains the weight of a cubic foot of each body in
avoirdupois ounces; from whence results the following rules: