THE CHARACTERISTICS OF CANNON
THE EARLY SMOOTHBORE CANNON
Soon after he found he could hurl a rock with his
good right arm, man learned about trajectorythe curved path taken
by a missile through the air. A baseball describes a "flat" trajectory
every time the pitcher throws a hard, fast one. Youngsters tossing the
ball to each other over a tall fence use "curved" or "high" trajectory.
In artillery, where trajectory is equally important, there are three
main types of cannon: (1) the flat trajectory gun, throwing shot at the
target in relatively level flight; (2) the high trajectory mortar, whose
shell will clear high obstacles and descend upon the target from above;
and (3) the howitzer, an in-between piece of medium-high trajectory,
combining the mobility of the fieldpiece with the large caliber of the
mortar.
The Spaniard, Luis Collado, mathematician, historian,
native of Lebrija in Andalusia, and, in 1592, royal engineer of His
Catholic Majesty's Army in Lombardy and Piedmont, defined artillery
broadly as "a machine of infinite importance." Ordnance he divided into
three classes, admittedly following the rules of the "German masters,
who were admired above any other nation for their founding and handling
of artillery." Culverins and sakers (Fig. 23a) were guns of the first
class, designed to strike the enemy from long range. The battering
cannon (fig. 23b) were second class pieces; they were to destroy forts
and walls and dismount the enemy's machines. Third class guns fired
stone balls to break and sink ships and defend batteries from assault;
such guns included the pedrero, mortar, and bombard (fig. 23c,d).
Collado's explanation of how the various guns were
invented is perhaps naive, but nevertheless interesting: "Although the
main intent of the inventors of this machine [artillery] was to fire and
offend the enemy from both near and afar, since this offense must be in
diverse ways it so happened that they formed various classes in this
manner: they came to realize that men were not satisfied with the
espingardas [small Moorish cannon], and for this reason the
musket was made; and likewise the esmeril and the falconet. And
although these fired longer shots, they made the demisaker. To remedy a
defect of that, the
sakers were made, and the demiculverins and culverins. While they were
deemed sufficient for making a long shot and striking the enemy from
afar, they were of little use as battering guns because they fire a
small ball. So they determined to found a second kind of piece,
wherewith, firing balls of much greater weight, they might realize their
intention. But discovering like-wise that this second kind of piece was
too powerful, heavy and costly for batteries and for defense against
assaults or ships and galleys, they made a third class of piece, lighter
in metal and taking less powder, to fire balls of stone. These are the
commonly called cañones de pedreros. All the classes of pieces
are different in range, manufacture and design. Even the method of
charging them is different."
FIGURE 22TRAJECTORIES. Maximum range of eighteenth century guns
was about 1 mile.
Guns could: Batter heavy construction with solid shot at long or
short range; destroy fort parapets and, by ricochet fire, dismount
cannon; shoot grape, canister, or bombs against massed personnel.
Mortars could: Reach
targets behind obstructions; use high angle fire to shoot bombs,
destroying construction and personnel.
Howitzers could:Move more easily in the field
than mortars; reach targets behind obstructions by high angle fire;
shoot larger projectiles than could field guns of similar weight.
It was most important for the artillerist to
understand the different classes of guns. As Collado quaintly phrased
it, "he who ignores the present lecture on this arte will, I
assert, never do a good thing." Cannon burst in the batteries every day
because gunners were ignorant of how the gun was made and what it was
meant to do. Nor was such ignorance confined to gunners alone. The will
and whim of the prince who ordered the ordnance or "the simple opinion
of the unexpert founder himself," were the guiding principles in gun
founding. "I am forced," wrote Collado, "to persuade the princes and
advise the founders that the making of artillery should always take into
account the purpose each piece must serve." This persuasion he undertook
in considerable detail.
The first class of guns were the long-range pieces,
comparatively "rich" in metal. In the following table from Collado, the
calibers and ranges for most Spanish guns of this class are given,
although as the second column shows, at this period calibers were
standardized only in a general way. For translation where possible, and
to list those which became the most popular calibers, we have added a
final column. Most of the guns were probably of culverin length: 30- to
32-caliber.
FIGURE 23SIXTEENTH CENTURY SPANISH ARTILLERY. Taken from
a 1592 manuscript, these drawings illustrate the three main
classes of artillery used by Spain during the early colonial period in
the New World. aCulverin (Class
1). bCannon (Class 2). cPedrero (Class 3). dMortar
(Class 3).
Sixteenth century Spanish cannon of the first class
Name of gun |
Weight of ball (pounds) |
Length of gun (in calibers) |
Range in yards |
Popular caliber |
Point- blank |
Maximum |
Esmeril | 1/2 |
|
208 | 750 |
1/2-pounder esmeril. |
Falconete | 1 to 2 |
|
|
|
1-pounder falconet. |
Falcon | 3 to 4 |
|
417 | 2,500 |
3-pounder falcon. |
Pasavolante | 1 to 15 | 40 to 44 |
500 | 4,166 |
6-pounder pasavolante. |
Media sacre | 5 to 7 |
|
417 | 3,750 |
6-pounder demisaker. |
Sacre | 7 to 10 |
|
|
|
9-pounder saker. |
Moyana | 8 to 10 | shorter than saker |
|
|
9-pounder moyenne. |
Media culebrina | 10 to 18 |
|
833 | 5,000 |
12-pounder demiculverin. |
Tercio de culebrina | 14 to 22 |
|
|
|
18-pounder third-culverin. |
Culebrina | 20, 24, 25, 30, 40, 50 |
30 to 32 | 1,742 |
6,666 | 24-pounder culverin. |
Culebrina real | 24 to 40 |
30 to 32 |
|
|
32-pounder culverin royal. |
Doble culebrina | 40 and up |
30 to 32 |
|
|
48-pounder double culverin. |
In view of the range Collado ascribes to the culverin, some remarks on
gun performances are in order. "Greatest random" was what the old time
gunner called his maximum range, and random it was. Beyond point-blank
range, the gunner was never sure of hitting his target. So with
smoothbores, long range was never of great importance. Culverins, with
their thick walls, long bores, and heavy powder charges, achieved
distance; but second class guns like field "cannon," with less metal and
smaller charges, ranged about 1,600 yards at a maximum, while the
effective range was hardly more than 500. Heavier pieces, such as the French
33-pounder battering cannon, might have a point-blank range of 720
yards; at 200-yard range its ball would penetrate from 12 to 24 feet of
earthwork, depending on how "poor and hungry" the earth was. At 130
yards a Dutch 48-pounder cannon put a ball 20 feet into a strong earth
rampart, while from 100 yards a 24-pounder siege cannon would bury the
ball 12 feet.
But generalizations on early cannon are
difficult, for it is not easy to find two "mathematicians" of the old
days whose ordnance lists agree. Spanish guns of the late 1500's do,
however, appear to be larger in caliber than pieces of similar name in
other countries, as is shown by comparing the culverins: the smallest
Spanish culebrina was a 20-pounder, but the French great
couleurine of 1551 was a 15-pounder and the typical English
culverin of that century was an 18-pounder.
Furthermore, midway of the 1500's, Henry II greatly simplified French
ordnance by holding his artillery down to the 33-pounder cannon,
15-pounder great culverin, 7-1/2-pounder bastard culverin, 2-pounder
small culverin, a 1-pounder falcon, and a 1/2-pounder falconet.
Therefore, any list like the one following must have its faults:
Principal English guns of the sixteenth century
Name |
Caliber (inches) |
Length |
Weight of gun (pounds) |
Weight of shot (pounds) |
Powder charge (pounds) |
Ft. | In. |
Rabinet |
1.0 |
|
300 |
0.3 |
0.18 |
Serpentine |
1.5 |
|
400 |
.5 |
.3 |
Falconet |
2.0 |
3 |
9 |
500 |
1.0 |
.4 |
Falcon |
2.5 |
6 |
0 |
680 |
2.0 |
1.2 |
Minion |
3.5 |
6 |
6 |
1,050 |
5.2 |
3 |
Saker |
3.65 |
6 |
11 |
1,400 |
6 |
4 |
Culverin bastard |
4.56 |
8 |
6 |
3,000 |
11 |
5.7 |
Demiculverin |
4.0 |
|
3,400 |
8 |
6 |
Basilisk |
5.0 |
|
4,000 |
14 |
9 |
Culverin |
5.2 |
10 |
11 |
4,840 |
18 |
12 |
Pedrero |
6.0 |
|
3,800 |
26 |
14 |
Demicannon |
6.4 |
11 |
0 |
4,000 |
32 |
18 |
Bastard cannon |
7.0 |
|
4,500 |
42 |
20 |
Cannon serpentine |
7.0 |
|
5,500 |
42 |
25 |
Cannon |
8.0 |
|
6,000 |
60 |
27 |
Cannon royal |
8.54 |
8 |
6 |
8,000 |
74 |
30 |
Like many gun names, the word "culverin" has a
metaphorical meaning. It derives from the Latin colubra (snake).
Similarly, the light gun called áspide or aspic, meaning
"asp-like," was named after the venomous asp. But these digressions
should not obscure the fact that both culverins and demiculverins were
highly esteemed on account of their range and the effectiveness of fire.
They were used for precision shooting such as building demolition, and
an expert gunner could cut out a section of stone wall with these guns
in short order.
As the fierce falcon hawk gave its name to the falcon
and falconet, so the saker was named for the saker hawk; rabinet,
meaning "rooster," was therefore a suitable name for the falcon's
small-bore cousin. The 9-pounder saker served well in any military
enterprise, and the moyana (or the French moyenne,
"middle-sized"), being a shorter gun of saker caliber, was a good naval
piece. The most powerful of the smaller pieces, however, was the
pasavolante, distinguishable by its great length. It was between
40 and 44 calibers long! In addition, it had thicker-bore walls than any
other small caliber gun, and the combination of length and weight
permitted an unusually heavy chargeas much powder as the ball
weighed. A 6-pound lead ball was what the typical pasavolante
fired; another gun of the same caliber firing an iron ball would be a
4-pounder. The point-blank range of this Spanish gum was a football field's length
farther than either the falcon or demisaker.
In today's Spanish, pasavolante means "fast
action," a phrase suggestive of the vicious impetuosity to be expected
from such a small but powerful cannon. Sometimes it was termed a
drajon, the English equivalent of which may be the drake, meaning
"dragon"; but perhaps its most popular name in the early days was
cerbatana, from Cerebus, the fierce three-headed dog of
mythology. Strange things happen to words: a cerbatana in modern
Spanish is a pea shooter.
Sixteenth century Spanish cannon of the second
class
Spanish name |
Weight of ball (pounds) |
Translation |
Quarto canon | 9 to 12 | Quarter-cannon. |
Tercio canon | 16 | Third-cannon. |
Medio canon | 24 | Demicannon. |
Canon de abatir | 32 | Siege cannon. |
Doble canon | 48 | Double cannon. |
Canon de bateria | 60 | Battering cannon. |
Serpentino |
| Serpentine. |
Quebrantamuro or lonbarda | 70 to 90 | Wallbreaker or lombard. |
Basilisco | 80 and up | Basilisk. |
The second class of guns were the only ones properly
called "cannon's in this early period. They were siege and battering
pieces, and in some few respects were similar to the howitzers of later
years. A typical Spanish cannon was only about two-thirds as long as a
culverin, and the bore walls were thinner. Naturally, the powder charge
was also reduced (half the ball's weight for a common cannon, while a
culverin took double that amount).
The Germans made their light cannon 18 calibers long.
Most Spanish siege and battering guns had this same proportion, for a
shorter gun would not burn all the powder efficiently, "which," said
Collado, "is a most grievous fault." However, small cannon of 18-caliber
length were too short; the muzzle blast tended to destroy the embrasure
of the parapet. For this reason, Spanish demicannon were as long as 24
calibers and the quarter-cannon ran up to 28. The 12-pounder
quarter-cannon, incidentally, was "culverined" or reinforced so that it
actually served in the field as a demiculverin.
The great weight of its projectile gave the double
cannon its name. The warden of the Castillo at Milan had some
130-pounders made, but such huge pieces were of little use, except in
permanent fortifications. It took a huge crew to move them, their
carriages broke under the concentrated weight, and they consumed
mountains of munitions. The lombard, which apparently originated in
Lombardy, and the basilisk had the same disadvantages. The fabled
basilisk was a serpent whose very look was fatal.
Its namesake in bronze was tremendously heavy, with
walls up to 4 calibers thick and a bore up to 30 calibers long. It was
seldom used by the Europeans, but the Turkish General Mustafa had a pair
of basilisks at the siege of Malta, in 1565, that fired 150- and
200-pound balls. The 200-pounder gun broke loose as it was being
transferred to a homeward bound galley and sank permanently to the
bottom of the sea. Its mate was left on the island, where it became an
object of great curiosity.
The third class of ordnance included the guns firing
stone projectiles, such as the pedrero (or perrier, petrary, cannon
petro, etc.), the mortars, and the old bombards like Edinburgh Castle's
famous Mons Meg. Bars of wrought iron were welded together to form Meg's
tube, and iron rings were clamped around the outside of the piece. In
spite of many accidents, this coopering technique persisted through the
fifteenth century. Mons Meg was made in two sections that screwed
together, forming a piece 13 feet long and 5 tons in weight.
Pedreros (fig. 23c) were comparatively light. The
foundryman used only half the metal he would put into a culverin, for
the stone projectile weighed only a third as much as an iron ball of the
same size, and the bore walls could therefore be comparatively thin.
They were made in calibers up to 50-pounders. There was a chamber for
the powder charge and little danger of the gun's bursting, unless a
foolhardy fellow loaded it with an iron ball. The wall thicknesses of
this gun are shown in Figure 24, where the inner circle represents the
diameter of the chamber, the next arc the bore caliber, and the outer
lines the respective diameters at chase, trunnions, and vent.
FIGURE 24HOW MUCH METAL WAS IN EARLY GUNS? The
charts compare the wall diameters of sixteenth-seventeenth century
types. The center circle represents the bore, while the three outer arcs
show the relative thickness of the bore wall at (1) the smallest
diameter of the chase, (2) at the trunnions, and (3) at the vent. The
small arc inside the bore indicates the powder chamber found in the
pedrero and mortar.
Mortars (fig. 23d) were excellent for "putting great
fear and terror in the souls of the besieged." Every night the mortars
would play upon the town: "it keeps them in constant turmoil, due to the
thought that some ball will fall upon their house." Mortars were
designed like pedreros, except much shorter. The convenient way to
charge them was with saquillos (small bags) of powder. "They
require," said Collado, "a larger mouthful than any other pieces."
Just as children range from slight to stocky in the
same family, there are light, medium, or heavy gunsall bearing the
same family name. The difference lies in how the piece was "fortified";
that is, how thick the founder cast the bore walls. The English language
has inelegantly descriptive terms for the three degrees of
"fortification": (1) bastard, (2) legitimate, and (3)
double-fortified. The thicker-walled guns used more powder. Spanish
double-fortified culverins were charged with the full weight of the ball
in powder; four-fifths that amount went into the legitimate, and only
two-thirds for the bastard culverin. In a short culverin (say, 24
calibers long instead of 30), the gunner used 24/30 of a standard
charge.
The yardstick for fortifying a gun was its caliber.
In a legitimate culverin of 6-inch caliber, for instance, the bore
wall at the vent might be one caliber (16/16 of the bore diameter) or 6
inches thick; at the trunnions it would be 10/16 or 4-1/8 inches, and
at the smallest diameter of the chase, 7/16 or 2-5/8 inches. This table
compares the three degrees of fortification used in Spanish
culverins:
| Wall thickness in 8ths of caliber |
Vent |
Trunnion |
Chase |
Bastard culverin | 7 | 5 | 3 |
Legitimate culverin | 8 | 5-1/2 | 3-1/2 |
Double-fortified culverin | 6-1/2 | 9 | 4 |
As with culverins, so with cannon. This is Collado's
table showing the fortification for Spanish cannon:
| Wall thickness in 8ths of caliber |
Vent |
Trunnion |
Chase |
Cañon sencillo (light cannon) | 6 | 4-1/2 | 2-1/2 |
Cañon común (common cannon) | 5 | 7 | 3-1/2 |
Canon reforzado (reinforced cannon) | 5-1/2 | 8 | 3-1/2 |
Since cast iron was weaker than bronze, the walls of cast-iron pieces
were even thicker than the culverins. Spanish iron guns were founded
with 300 pounds of metal for each pound of the ball, and in lengths from
18 to 20 calibers. English, Irish, and Swedish iron guns of the period,
Collado noted, had slightly more metal in them than even the Spaniards
recommended.
FIGURE 25SIXTEENTH CENTURY CHAMBERED CANNON. a"Bell-chambered"
demicannon. bChambered demicannon.
Another way the designers tried to gain strength
without loading the gun with metal was by using a powder chamber. A
chambered cannon (fig. 25b) might be fortified like either the light or
the common cannon, but it would have a cylindrical chamber about
two-thirds of a caliber in diameter and four calibers long. It was not
always easy, however, to get the powder into the chamber. Collado
reported that many a good artillerist dumped the powder almost in the
middle of the gun. When his ladle hit the mouth of the chamber, he
thought he was at the bottom of the bore! The cylindrical chamber was
somewhat improved by a cone-shaped taper, which the Spaniards called
encampanado or "bell-chambered." A cañon encampanado
(fig. 25a) was a good long-range gun, strong, yet light. But it was hard
to cut a ladle for the long, tapered chamber.
Of all these guns, the reinforced cannon, was one of
the best. Since it had almost as much metal as a culverin, it lacked the
defects of the chambered pieces. A 60-pounder reinforced cannon fired
a convenient 55-pound ball, was easy to move, load, and clean, and held
up well under any kind of service. It cooled quickly. Either cannon
powder or fine powder (up to two-thirds the ball's weight) could be used
in it. Reinforced cannon were an important factor in any enterprise, as
King Philip's famed "Twelve Apostles" proved during the Flanders
wars.
Fortification of sixteenth and seventeenth century
guns
Spanish guns |
Thickness of bore wall
in 8ths of the caliber |
English guns |
Vent |
Trunnions |
Chase |
Light cannon; bell-chambered cannon |
6 | 4-1/2 | 2-1/2 | Bastard cannon. |
Demicannon |
6 | 5 | 3 |
|
Common cannon; common siege cannon |
7 | 5 | 3-1/2 |
|
Light culverin; common battering cannon |
7 | 5 | 3 | Bastard culverin; legitimate cannon. |
Common culverin; reinforced cannon |
8 | 5-1/2 | 3-1/2 | Legitimate culverin; double-fortified cannon. |
Legitimate culverin |
9 | 6-1/2 | 4 | Double-fortified culverin. |
Cast-iron cannon |
10 | 8 | 5 |
|
Pasavolante |
11-1/2 | 8-1/2 | 5-1/2 |
|
While there was little real progress in mobility
until the days of Gustavus Adolphus, the wheeled artillery carriage
seems to have been invented by the Venetians in the fifteenth century.
The essential parts of the design were early established: two large,
heavy cheeks or side pieces set on an axle and connected by transoms.
The gun was cradled between the cheeks, the rear ends of which formed a
"trail" for stabilizing and maneuvering the piece.
Wheels were perhaps the greatest problem. As early as
the 1500's carpenters and wheelwrights were debating whether dished
wheels were best. "They say," reported Collado, "that the
[dished] wheel will never twist when the artillery is on the march.
Others say that a wheel with spokes angled beyond the cask cannot carry
the weight of the piece without twisting the spoke, so the wheel does
not last long. I am of the same opinion, for it is certain that a
perpendicular wheel will suffer more weight than the other. The defect
of twisting under the pieces when on the march will be remedied by
making the cart a little wider than usual." However, advocates of the
dished wheel finally won.
|