Chapter XXIII: Appendix: Rifle Cannon

A _rifle_ is a firearm which has spiral grooves cut into the surface of its bore, for the purpose of communicating a rotary motion to a projectile around an axis coinciding with the direction of its flight.

The object of this rotation is to increase the range of a projectile, by causing it to move through the air in the direction of its least resistance, and to correct the cause of deviation by distributing it uniformly around the line of flight.

Various plans have been tried to secure the safest and surest means of causing the projectile to follow the spiral grooves as it passes along the bore of a rifled piece. Those projectiles, which promise to be the most successful for heavy guns, may be ranged under two heads, viz:

1st. Those which have flanges or projections on them to fit into the grooves of the gun in loading.

The flanges are made of softer metal than the body of the projectile.

2d. Those which are constructed on an expanding principle.

[Sidenote: 164]]

The body is generally made of cast-iron; and the expanding portion is a band or cup of some softer metal, as _pewter_, _copper_, or _wrought iron_, which enters the bore of the piece freely when it is loaded, but which is forced into the grooves by the discharge.

The grooves are of different forms, determined by the angle made by the tangent line at any point with the corresponding element of the bore. If the angles be equal at all points, the groove is said to be _uniform_. If they increase from the breech to the muzzle, the grooves are called _increasing_; if the reverse, _decreasing_ grooves. The practical method of cutting grooves consists in moving a rod armed with a cutter, back and forth in the bore, and at the same time revolving it around its axis. If the velocities of translation and rotation be both uniform, the grooves will have a uniform twist; if one of the velocities be variable, the grooves will be either increasing or decreasing, depending on the relative velocities in the two directions.

_Twist_ is the term employed by gunmakers to express the inclination of a groove at any point, and is measured by the tangent of the angle which the groove makes with the axis of the bore; and this is _always equal to the circumference of the bore divided by the length of a single revolution of the spiral measured in the direction of the axis_.

The most suitable inclination of grooves for a rifle cannon has not yet been determined experimentally; and consequently a wide diversity of twists is employed by different experimenters.

The following table[4] presents a synopsis of the results in case of some rifle cannon tested at Fort Monroe, Va., in 1859, by a Board composed of ordnance and artillery officers.

[4] See Table, pages 126, 127.

[Sidenote: 165]]

The following is extracted from the report of the Board:

“The method of obtaining rifle motion in these different guns is of two kinds:

“1. Flanged projectiles entering into the grooves of the gun.

“2. Expanding projectiles, which are forced into the grooves by the action of the charge. Although the flanged projectile, when made with great precision, has given good results, as shown by the tables of firing, the extreme nicety in its fabrication, and the care and trouble to load the gun, particularly when it becomes foul by firing, seems to render it not as suitable for service as the expanding projectile.

* * * * *

“From the results obtained, the conclusion is inevitable that the era of smooth-bore field artillery has passed away, and that the period of the adoption of rifle cannon for siege and garrison service cannot be remote. The superiority of elongated projectiles, whether solid or hollow, with the rifle rotation, as regards economy of ammunition, extent of range, and uniformity and accuracy of effect, over the present system, is decided and unquestionable.”

The ARMSTRONG GUN, of which so much has been said, belongs to the class of breech-loading rifle-cannon. Its projectile is made of cast-iron, surrounded by two leaden rings, placed at the extremities of the cylindrical part, for the purpose of engaging the grooves, when it is forced through the bore. The great range and accuracy claimed for this projectile, are probably derived from its great length compared with its diameter; but a gun of great strength would be required to project it.

[Sidenote: 166]]

TARGET 40' BY 20'.

====================================================================
| | Bore. | Grooves. |
Name.|Calibre+-----+-------+---+------+---------+ Twist.
| |Diam-| | | | |
| |eter.|Length.|No.|Width.| Depth. |
------+-------+-----+-------+---+------+---------+------------------
| | in. | in. | | in. | in. |
Sawyer,|24-pdr.|5.862| 110 | 6 | 1.5 | 0.25 |Uniform, one turn
| | | | | | | in 34⅓ feet.
| | | | | | |
Dimick,|32-pdr.|6.4 | 101 | 6 | 2.0 | 0.2 |Increasing from 0
| | | | | | rectan. |to one turn in 62½
| | | | | | |feet at muzzle;
| | | | | | |twist to the right
| | | | | | |
Dr. |12-pdr.|4.854| 109 | 7 |¹/₁₄th|.03 to |Increasing from 0
Read,| Siege | | | |circum| .08 | at commencem’t
| | | | | | | to one turn in 50
| | | | | | | feet at muzzle.
| | | | | | |
Do. |12-pr. |4.636| 74 | 7 | do. | do. | Do. do.
| Field | | | | | |
| | | | | | |
Do. |32-pr. |6.425| 110 | 3 | ¹/₆th| .085 |Uniform, one turn
| | | | |circum| to .12 | in 40 feet.
| | | | | | circular|
| | | | | | |
Do. | 6-pr. |3.69 | 103.4 | 3 | do. | .077 |Uniform, to the
| | | | | | to .111 | right, one turn
| | | | | | circular| in 25 feet.
| | | | | | |
| | | | | | |
Capt. | 3-pr. |2.9 | 44.5 | 8 | 0.4 | .05 |Uniform, one turn
Dyer,| | | | | | | in 16 feet.
| | | | | | |
Do. |6-pr. |3.67 | 57.5 |16 | 0.5 | .025 |Uniform, one turn
| bronze| | | | | | in 19 feet.
------+-------+-----+-------+---+------+---------+------------------

[Sidenote: 167]]

Legend:
(A) = Weight of Projectile.
(B) = Weight of Charge.
(C) = No. fo shots fired.
(D) = No. of direct hits.
(E) = No. of ricochet hits.
(F) = Angle of Elevation.
(G) = Time of flight.

======================================================
|Weight| | | 1000 YARDS. |
| of | | +----+----+---+------+-------+
Name | Gun. | (A)| (B)| (C)|(D) |(E)| (F) | (G) |
-------+------+----+----+----+----+---+------+-------+
| lbs. |lbs.|lbs.| | | | ° ' | " |
Sawyer,| 8822 | 45 | 5½ | 15 | 13 | 2 | 2 | |
| | | | | | | | |
| | | | | | | | |
Dimick,| 9300 | 51 | | 7 | 5 | 1 | 2 15 | |
| | | | | | | | |
| | | | | | | | |
| | | | | | | | |
| | | | | | | | |
Dr. | 5000 | 22 | 3 | 26 | 14 | 9 | 2 15 | |
Reed, | | | | | | | | |
| | | | | | | | |
| | | | | | | | |
| | | | | | | | |
Do. | 1900 | 15 | 2 | 48 | 16 | 3 | 2 | 3 |
| | | | | | | | |
Do. | 8500 | 50 | 6 | 10 | 8 | 2 | 2 15 | 3 |
| | | | | | | | |
| | | | | | | | |
Do. | 1200 | 12 | 1½ | 28 | 18 | 4 | 2 10 | |
| | | | | | | | |
| | | | | | | | |
| | | | | | | | |
Capt. | 250 | 9 | 1 | 28 | 16 | 5 | 2 25 | |
Dyer, | | | | | | | | |
| | | | | | | | |
Do. | 880 | 14 | 1½ | 22 | 11 | 4 | 2 15 | |
| | | | | | | | |
-------+------+----+----+----+----+---+------+-------+

Legend:
(A) = Weight of Projectile.
(B) = Weight of Charge.
(C) = No. fo shots fired.
(D) = No. of direct hits.
(E) = No. of ricochet hits.
(F) = Angle of Elevation.
(G) = Time of flight.
(H) = Corresponding Elevation.
====================================================================
| | | | 2000 YARDS. | | |
|Weight| | +---+---+-----+-----+----+ Avg. | |
Name | of | (A)| (B)|(C)|(D)| (E) | (F) | (G)|range.| (H) |(G)
| Gun. | | | | | | | | | |
| | | | | | | | | | |
| | | | | | | | | | |
-------+------+----+----+---+---+-----+-----+----+------+-------+---
| lbs. |lbs.|lbs.| | | |° ' | " | | ° ' | "
Sawyer,| 8822 | 45 | 5½ |119| 32| 17 |4 30 | 6 | 4359 | 13½ |
| | | | | | | | | | |
| | | | | | | | | | |
Dimick,| 9300 | 51 | 6 | 58| 21| 6 |5 | 6½ | | |
| | | | | | | | | | |
| | | | | | | | | | |
| | | | | | | | | | |
| | | | | | | | | | |
Dr. | 5000 | 22 | 3 | 30| 5| 8 |4 30 | | | |
Reed, | | | | | | | | | | |
| | | | | | | | | | |
| | | | | | | | | | |
| | | | | | | | | | |
Do. | 1900 | 15 | 2 | | | | | | | |
| | | | | | | | | | |
Do. | 8500 | 50 | 6 | 84| 19| 8 |5 | 6⅓ | 3665 | 11 30 |
| | | | | | | | | | |
| | | | | | | | | | |
Do. | 1200 | 12 | 1½ | 52| 9| 5 |4 45 | | | |
| | | | | | | | | | |
| | | | | | | | | | |
| | | | | | | | | | |
Capt. | 250 | 9 | 1 | 18| 4| 2 |5½ | 7 | 3270 | 13 30 | 15
Dyer, | | | | | | | | | | |
| | | | | | | | | | |
Do. | 880 | 14 | 1½ | | | | | | | |
| | | | | | | | | | |
-------+------+----+----+---+---+-----+-----+----+------+-------+---

The following is a description of the several projectiles, viz:

SAWYER’S.—Flanged projectile; elongated;
entire shell coated with an alloy chiefly of
lead, and has a percussion cap on small end.

DIMICK’S.—Expanding shell; elongated; cup of
soft metal cast on rear end of projectile.

REED’S.—The body is of cast-iron and the
expanding portion is a cup of wrought iron, which
is fastened to the body by inserting it in the
mould and pouring the melted metal around it.

DYER’S.—Description nearly the same as that
of Dimick’s.

INDEX.

The pages refer to the sidenotes in the margin of the text.

AIR: Resistance of, 148.
AMMUNITION: For field battery, 41;
for seige train, 37-8;
storage 103-4;
preparation, 93-4, 100-1-2;
weights of fixed, 107.
ANGLE: Of greatest range, 66;
of fall, 74;
of least elevation for mortars, 67;
of elevation for stone-mortars, 67
—Natural angle of sight, 12;
of guns, 26;
of howitzers, 29;
of columbiads, 30.
ANIMAL POWER, 152.
ARC, elevating, 18.
AREA of a circle, 154.
ARMSTRONG GUN, 165.
ARTIFICIAL LINE OF SIGHT, 53.
ARTILLERY: Definition, 9
—Method of embarking and disembarking, 161-2
—Carriages (see _carriages_)
—Kinds of, 9;
how distinguished, 9
—Proportion of, to Infantry, 40
—Proportion of different kinds in a field train, 40;
in seige train, 36;
for mountain service, 42;
for armament of forts, 35
—How rendered unserviceable, 20-1.
ASTRAGAL AND FILLETS: Definition, 13.
ATTACK of a post, 150.
AVOIRDUPOIS WEIGHT, 159.
AXIS OF A PIECE: Definition, 12.

BALLS: Diameters and weights, 105-6;
computation of weight and diameter, 95;
piling, 103;
number in a pile, 104-5;
fire, 92;
light, 92;
smoke, 93;
penetration, 149-50.
BARBETTE CARRIAGE: Kinds, 132
—Parts composing, 133
—Description, 133-4.
BARRELS: For gunpowder, marking, 88;
piling, 88;
transportation, 89.
BATTERY: Definition of, 11
—Of field artillery, composition, 41;
tactics, 44-5-6-7-8-9, 50
—Mountain Artillery, 42
—Ammunition for field battery, 41.
BATTERY-WAGON, 143-4.
BASE-RING: Definition, 13.
BASE OF THE BREECH: Definition of, 13.
BEDS, mortar: Weights, 33
—Trunnion-beds, 129
—Siege mortar, 130-1
—Coehorn, 131
—Eprouvette, 131
—Heavy sea-coast, 131-2.
BOARD, Pointing, 58.
BORE: Definition, 14; bottom of, 15.
BORMANN FUZE, 112-13.
BRASS CANNON: External injury, 23.
BREADTH of a river ascertained, 157-8.
BREACHING: Battery, best position for, 38;
manner of, 38-9;
time required, 39.
BREECH: Definition, 13
—Sights, 16;
how used, 53;
construction, 17;
pieces supplied with, 17.
BRONZE: Objections to, for cannon, 10;
why used for field pieces, 10;
kinds of bronze pieces used, 11.
BURNING gunpowder: Quickness of, 87.
BURSTING OPEN gates, 158.
BUSHING a piece, 20;
metal used for, in bronze pieces, 20;
object of, 20;
all new artillery not bushed, 20.

CAISSON: Description of, 142-3;
number with a field battery, 41.
CAKING of powder prevented, 89.
CALIBRE: Definition, 12;
number in a piece ascertained, 12.
CANISTERS, 91: For field service, how made, 94;
for siege and sea-coast service, how made, 95
—How piled, 104.
CANNON: Bore, 12
—Brass, external and internal injuries, 23
—Dimensions, how regulated, 11
—For siege train, 36
—Iron, injuries, 24
—preservation of, 25;
service of, how judged, 24
—How marked, 21-2
—Condemned cannon, how marked, 22
—Proof of, 22
—Kinds, 9
—Length of, 27-8, 30, 33
—Rifle cannon, 163-7.
CARCASSES, 92.
CARRIAGES: Classification, 123
—Movable, 123;
field gun, 125-6;
mountain artillery, 127;
prairie, 127;
limbers, 126-9;
siege-gun, 128
—Stationary, 129-30;
barbette, 132-3-4;
casemate, 138-9;
columbiad, 136-7;
flank-casemate, 140
—Mortar beds, 131
—Wrought iron, 141-2
—Number in a field battery, 41.
CARTRIDGE BAGS: Where filled, 89.
CARTRIDGES: For hot shot, 97.
CASCABLE, 13.
CASEMATE: Carriage, 138-9
—Gin, 146.
CHAMBER: Definition, 14;
object of, 32;
form for mortars, 32;
for howitzers, 28;
for eprouvette, 32;
gomer, 32.
CHARGES: Definition, 60
—For breeching, 60
—For double shot, 60
—For field guns and howitzers, 62
—For fire-balls, 61
—For heavy guns, columbiads and howitzers, 62
—Service charge for heavy guns, 60
—For hot shot, 60
—Greatest charges for mortars, 62
—For mortars, how regulated, 61
—For ricochet firing, 60
—For shells fired from columbiads and heavy guns, 108
—For field shells, 108
—For mortar shells, 107
—For spherical case shot, 108.
CHASE: Definition, 13.
CHASSIS: For barbette carriage, 134-5
—For casemate, carriage, 139-40
—For columbiad, 138
—For flank-casemate, 141
—For wrought iron carriage, 142.
CHEEKS, 124.
COEHORN MORTAR: Diameter, 33
—Weight of bed, 33
—Length of, 33
—Length of bore, 33
—Length of chamber, 33
—Use, 34
—Greatest charge for, 62
—Bed, description of, 131.
COLUMBIADS: Definition, 30
—Windage, 82
—Charges, 62
—Chamber, 30
—Peculiarities, 30
—Weights, 30
—Length, 30
—Natural angle of sight, 30
—Gun carriage, 136-7;
chassis, 137-8
—Shells, charges for, 108;
method of loading, 102.
COMPOSITION, for preserving iron pieces, 160;
application, 160;
for axle-trees of carriages, 158.
CONDEMNED cannon, how marked, 22;
shot, how marked, 102.
CONTENT: Of a barrel, 155;
box, 155;
conic frustum, 154;
gomer chamber, 155;
spherical segment, 155;
cylinder, 155.

DAY’S MARCH: Of field artillery, 153.
DEFILADE: Definition, 156.
DEPTH OF PENETRATION of balls, 149-50.
DESCENT of falling bodies: Law of, 159.
DIAMETER: Of coehorn mortar, 33;
of eprouvette, 33;
of stone-mortar, 33;
of cast-iron shot, how found, 95;
of shot, shells, and spherical case, 105;
of vent, 16.
DIMENSIONS: Of cannon, how regulated, 11;
of a parapet to resist field artillery, 156.
DIPPING OF THE MUZZLE, 77-8.
DISCHARGES: Number an iron gun can sustain, 39.
DISH, of a wheel, 124.
DIRECTION, how given: To guns and howitzers, 51-2;
to mortars, 56-8
—At night, 55, 59
—When wheels are not on same level, 54.
DISTANCE: For firing field pieces, 46
—Ascertained by sound, 151
—Determined by a tangent scale, 158
—Of recoil, 77
—Of ricochet battery from object, 74.
DISPART: Definition, 13.
DOLPHINS: Definition, 19;
pieces furnished with, 19.
DRIVING OUT shot wedged in the bore, 21.

ELEVATION: Necessity for, 51
—How given to guns and howitzers, 52;
to mortars, 56;
instruments for, 52
—Angle of, for mortars 67;
greatest angle _in vacuo_, 66;
angle of, for ricochet fire, 74.
ELEVATING ARC, 18.
EMBARKING: Artillery and its stores, 161-2.
ENFILADE: Definition, 156.
ENFILADING a work, 73-4-5
—Object to be fired at, 73.
EPROUVETTE, 11;
form of chamber, 32
—Calibre, 33
—Use of, 34
—Bed, 33, 131
—Length of bore, 33.
EXPANSION of hot shot, 96.
EXTERNAL injury to cannon, 23-4.

FACE of the piece: Definition of, 14.
FALL: Point of, 73
—Angle of, 74.
FALLING BODIES, law of descent, 159.
FIELD ARTILLERY: Charges for, 62
—Kinds, 40
—Tactics, 44-9, 50.
FIELD BATTERY: Number of pieces, 40
—Battery of horse-artillery, 41
—Composition of, on a war establishment, 41
—Composition of mountain howitzer battery, 42
—Ammunition, 41
—Draught horses, 42.
FIELD GUN, how mounted, 44
—Charges for, 62.
FIELD CARRIAGES: Kinds of, 125
—Description, 125-6.
FIELD AND SIEGE GIN, 146.
FIELD SHELLS: Loading, 100
—Charges, 108.
FIELD-PARK, 42;
quantity of supplies for, 42;
carriages, 43.
FILLING: Mortar shells, 101;
columbiad shells, &c., 102.
FIRE BALLS: Definition, 92
—Charges, 61
—How preserved, 104.
FIRING: Field pieces, 46-7-8
—Rapidity of, for mortars, 34;
for field pieces, 46
—Within point-blank range, rule for, 52
—At night with guns and howitzers, 55;
with mortars, 59
—Mode of facilitating firing for any given distance, 54;
use of remarkable points on the ground, 55
—Ricochet firing, 73
—Effect of firing upwards under a large angle, 65.
FIXED AMMUNITION: Storing, 103-4
—Weights of, 107.
FLIGHT OF PROJECTILES: Time of, 149.
FLANK-CASEMATE carriage, 140-41.
FOOT, number of gallons in a cubic, 160.
FOOT SOLDIER, space occupied by, in ranks, 153.
FORGE, 143
—Portable, 144
—Number with a field battery, 41;
with field-park, 43.
FORCES acting on a projectile, 51.
FORCE of gravity, 159.
FRICTION PRIMER: Description, 115;
advantages of, 116.
FURNACES for hot shot, 97.
FUZES: Definition, 109
—Wooden, 109-10
—Paper, 111
—Bormann, 112-13
—U. S. sea-coast, 114
—Composition for mortar fuzes, 110;
for paper fuzes, 111.

GINS: Field and siege, 146;
garrison, 146;
casemate, 146.
GOMER CHAMBER, 32.
GRAPE SHOT, 91;
weight of, 107.
GRATES for heating shot, 98.
GRAVITY: Specific, 159
—Force of, 159.
GREASE for wheels, 158.
GROOVES for rifle cannon, 163-4.
GRENADES: 91
—Angle of elevation for, when thrown from stone-mortars, 67.
GROMMETS, 99.
GUNS: Definition, 26
—Lengths, 27
—Weights, 27
—Proof, 22
—Ranges, 68-9, 70-1-2
—Nomenclature, 13, 14, 15
—Principal parts of, 26
—Projectiles used with, 27
—How mounted, 26
—Natural angle of sight of, 26.
GUN METAL: Bronze, 9, 10
—cast-iron, 9, 10.
GUNNERS’ IMPLEMENTS: Level, 18
—Quadrant, 18
—How used, 52-3.
GUN-CARRIAGES: Field, 125-6;
siege, 128;
barbette, 132-4;
casemate, 138-9;
flank-casemate, 140;
mountain howitzer, 127;
wrought iron, 141;
prairie, 127-8
—Columbiad, 136-7.
GUNPOWDER: Materials, 83
—Proportions, 83
—Manufacture, 84
—Qualities of, 87
—Packing, 87-8
—Proving, 86
—Expansive velocity and pressure, 87
—Hygrometric proof, 87
—Relative quickness, 87
—Preservation and storage, 88-9
—Transportation, 89.

HAND-CART, 145.
HAND SLING-CART, 145-6.
HAUSSE: Pendulum, 17.
HAY: Weight of, 154.
HORSES: Number required for a field battery, 42;
for siege train, 37
—Power of, 152
—Space occupied by, 152
—Number required for siege-gun, 129
—Weight, 152.
HORSE-ARTILLERY: Peculiar advantages of, 43.
HOT SHOT, 97-8
—Loading with, 97
—Expansion of, 96.
HOWITZERS: Definition, 28
—Kinds of, and weights, 29;
—Lengths, 28-9
—Number in field battery, 41;
in siege train, 36
—Chamber, form of, 28
—Advantages of, 28
—Projectiles used with, 28
—Natural angle of sight of, 29
—Charges for, 62
—Pointing, 51.

ICE: Strength of, 156.
IMPLEMENTS: Quadrant, 18;
breech-sight, 16;
pendulum hausse, 17;
gunner’s perpendicular, 18;
pointing stakes, 57-8;
pointing-wires, 56;
plummet, 18, 58;
pointing-cord, 57.
INCENDIARY COMPOSITION, 117.
INJURIES to cannon, 23.
IRON preferred to bronze, 10.
IRON CANNON used in land service, 10, 11.

JUNK-WADS, 99.

KNOB of cascable, 13;
use of, 19.

LACQUER, for iron guns, 160.
LENGTH of cannon: Definition of, 11
—Extreme length, 12.
LINE: Of fire, 64
—Of metal, 12;
how directed, 52-3;
not permanent, 54
—Artificial line of sight, 53.
LIGHT BALLS, 92.
LIMBERS: For field carriages, 126;
for siege-carriages, 129.
LOADING: With hot shot, 97
—Field shells, 100
—Spherical case, 101-2
—Mortar shells, 101-2
—Shells for columbiads and other heavy guns, 102.

MAGAZINES: Moisture of, how absorbed, 89;
powder stored in, 88;
precautions to be observed when open, 89.
MARKING: Cannon, 21-2;
condemned shot and shell, 102;
powder barrels, 88.
MARCHES: Horse-artillery, field-artillery, cavalry, and infantry, 153.
MATCH: Quick, 116; slow, 116.
METALS for artillery, 9.
MOMENTUM, 151.
MORTAR WAGON, 145.
MORTARS, 31
—Advantages of, 31
—Lengths and weights, 33
—Kinds, 11
—Beds, weights of, 33
—Platform, 121
—Form of chamber, 32
—Length of chamber and of bore, 33
—Kinds of projectiles used with, 34
—Rapidity of fire of siege mortars, 34
—Pointing, 56, 58;
Greatest charges for, 62
—Angles of elevation for, 66-7
—Siege mortar beds, 130-1
—Coehorn mortar bed, 131
—Eprouvette bed, 131
—Sea-coast mortar bed, 132.
MOUNTAIN artillery: Dimension and weights of, 29
—Composition of a battery, 42
—Ranges, 69.
MULES: Strength of, 152.
MUZZLE: Definition, 15
—Sight, 17.

NATURAL ANGLE of sight, 12.
NECK: Definition, 14.
NOMENCLATURE of a piece, 13, 14, 15.
NIGHT firing: With guns and howitzers, 55;
with mortars, 59.

OATS: Weight of, 154.

PACK horses, 152.
PENDULUM HAUSSE, 17.
PENDULUMS: Length of, 158.
PENETRATION of balls: In masonry, 150;
in earth, 150.
PERPENDICULAR, gunner’s, 18.
PILING: Balls, 103
—Canisters, 104
—Loaded shells, 104
—Powder-barrels, 88
—Number of shot in a pile, 104-5.
PLATFORMS, 118
—Siege, 119-20
—Mortar, 121
—Rail, 121
—Ricochet, 122.
PLUMMET: For mortar service, 18, 58
—For regulating march of infantry, 161.
POINT-BLANK RANGE, 63-4
—Causes which vary it, 64
—Effect on it of firing upwards under a large angle, 65.
POINTING: Guns and howitzers, 51
—Mortars, 56
—Stakes, 57-8
—Wires, 56
—Cord, 57
—Board, 58.
PORT FIRES, 114
—Composition for, 115.
POINT of fall, 73-4.
PRAIRIE CARRIAGE, 127-8.
PREPONDERANCE: Definition, 19
—Why given, 19.
PRIMERS: Friction, 115.
PRIMING-TUBES, 115.
PRESERVATION: Of cannon, 25
—Fixed ammunition, 103-4
—Balls, 102
—Grape and canister, 103
—Fire balls, 104.
PROJECTILES: Solid shot, 90
—Shell, 90
—Spherical case, 90
—Canister, 91
—Grape, 91
—Grenades, 91
—Carcasses, 92
—Fire-balls, 92
—Light balls, 92
—Smoke balls, 93
—Hot shot, 97-8
—Forces acting on, when fired from a piece, 51
—Kind used with field pieces, and distance at
which they should be employed, 46.

QUADRANT, gunners: How used, 52-3.
QUARTER-SIGHTS, 16.
QUICK-MATCH, 116
—How set fire to, 117.

RANGES: Definition, 63
—Point-blank, 63
—British point-blank, 63
—Causes which vary point-blank, 64
—Extreme range, 66
—Angle of greatest range _in vacuo_, 66
—Tables of, 68-9, 70-1-2
—How ascertained, 149.
RATE OF MARCH of horse-artillery, cavalry, and infantry, 153.
RECOIL: Definition, 77
—Cause of, 77
—Amount, 77
—Has no appreciable effect on flight of projectile, 78
—Influence of position of axis of trunnions on, 78-9.
REINFORCE, 13
—Band, 13.
RESISTANCE OF AIR to projectiles, 147-8.
RICOCHET: Definition, 73
—Object of, 73
—How conducted, 74-5
—Advantages of, 73
—Nature of, 75
—Charges for a _flattened_ ricochet, 76;
for _curvated_, 76
—Tables of ricochet firing, 76
—Pieces best adapted for, 75
—Distance from object of ricochet battery, 74
—Greatest angle of elevation for ricochet firing, 74.
RIFLE-CANNON: Experiments at Fort Monroe, 166-7
—Armstrong gun, 165.
RIMBASES, 14.
RING WADS, 94.
RIVERS: Breadth, 156-7.
ROPES: size and strength of, 156.

SABOTS: Difference in, for field service, 93
—Arrangement for field guns and 12-pdr. field howitzer, 93;
in 24 and 32-pdr. field howitzers, 93
—Mode of fastening sabots to projectiles for field-service, 93-4;
for heavy shells, 94;
for canisters, 94-5;
for grape shot, 95.
SEA-COAST PIECES, how mounted, 35
—Number and kind required for sea-board forts, 35
—Heavy sea-coast mortar-bed, 131-2.
SCALING a piece, 21.
SHOT: Solid, 90
—Hollow, 90
—Rule for finding weights and diameters of cast-iron shot, 95
—Condemned shot, how marked, 102
—Piling, 103-4
—Preservation, 102-3
—Forces acting on a shot, 51
—Penetration, 149-50
—Time required to heat, 97-8
—Expansion of by heat, 96
—Ranges of, 68-72
—Method of driving out shot wedged in the bore, 21
—Velocity of, 147.
SHELLS, 90;
—Dimensions and weights, 106-7
—Mode of computing weight of, 95
—Quantity of powder to fill, 96
—Strapping, 93
—Loading, 100-1-2
—Ranges, 68-72
—Condemned, how marked,102
—Velocity, 147.
SIGHTS of a piece: Definition, 12
—How determined, 12
—Quarter, 16.
SIEGE ARTILLERY: Kinds, 36
—Proportions in a siege train, 36;
of carriages, 36-7;
draught horses, 37;
projectiles and ammunition, 37-8
—Siege mortar-beds, 130-1.
SLING-CART: Hand, 146.
SLOW MATCH, 116.
SMOKE BALLS, 93.
SOUND: Velocity, 151
—Distance determined by, 151.
SPECIFIC GRAVITY, 159.
SPHERICAL CASE, 90
—Loading, 100-1.
SPIKING cannon, 20.
STAKES, pointing: How planted, 57-8.
STONE MORTAR: Length, 33
—Weight, 33
—Calibre, 33
—Length of bore, 33
—Length of chamber, 33
—Use of, 34
—Stones, how disposed, 34.
STORING of fixed ammunition, 103-4.
STRAPPING SHOT and shells, 93-4.
STRENGTH: Of ice, 156
—Of rope, 156.
SWELL of the muzzle, 14.

TABLES: Of charges, 62
—Of ranges, 68-9, 70-1-2
—Of windage, 81-2
—Of weights of projectiles, 106-7
—Of measures, 159
—Of avoirdupois weight, 159.
TACTICS of field artillery, 44-5-6-7-8-9-50.
TANGENT SCALE, 16.
TIME OF FLIGHT for siege-mortars, 67
—How found, 149.
TRAJECTORY, 64.
TRANSPORTATION: Of artillery by sea, 161-2
—Of siege-guns, 129.
TRAVERSE circles, 135.
TRUNNIONS: Definition, 14
—Use, 19
—Position in mortars, 31
—Beds, 129.
TRUE WINDAGE: Definition, 15.

UNSPIKING cannon, 21.

VALENCIENNES composition, 117.
VELOCITY: Of balls, 147
—Loss of, by resistance of air, 147
—Of sound, 151
—Loss of, by windage, 81.
VENT: Definition, 15
—Position and diameter of, 16.
VERTICAL FIRE, 31.

WADS: Grommet, 99
—Junk, 99
—Hay, for firing hot shot, 98.
WATER: Weight of, 161
—Allowance for a man and a horse, 154.
WEIGHTS: Guns, 27
—Columbiads, 30
—Howitzers, 29
—Mortars, 33
—Projectiles, 106-7
—Of wheels for field carriages, 144;
and for siege-carriages, 144
—Proportion between weights of shot, 95
—Of cast-iron shot or shell, how determined, 95
—Quantity of powder to fill a shell, how found, 96
—Carried by horses, 152
—Carried by an infantry soldier, 154.
WHEELS: Field-carriage, size and weight, 144
—Siege carriage, size and weight, 144
—Parts of, 124.
WINDAGE: Definition, 80
—Amount, 81-2
—Loss of velocity by, 81
—Advantage of a reduction of, 81.
WIRES, pointing, 56.