Artillery Through the Ages
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Albert Manucy >> Artillery Through the Ages
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GUNPOWDER
Black powder was used in all firearms until smokeless and other type
propellants were invented in the latter 1800's. "Black" powder (which
was sometimes brown) is a mixture of about 75 parts saltpeter
(potassium nitrate), 15 parts charcoal, and 10 parts sulphur by
weight. It will explode because the mixture contains the necessary
amount of oxygen for its own combustion. When it burns, it liberates
smoky gases (mainly nitrogen and carbon dioxide) that occupy some 300
times as much space as the powder itself.
Early European powder "recipes" called for equal parts of the three
ingredients, but gradually the amount of saltpeter was increased until
Tartaglia reported the proportions to be 4-1-1. By the late 1700's
"common war powder" was made 6-1-1, and not until the next century was
the formula refined to the 75-15-10 composition in majority use when
the newer propellants arrived on the scene.
As the name suggests, this explosive was originally in the form of
powder or dust. The primitive formula burned slowly and gave low
pressures--fortunate characteristics in view of the barrel-stave
construction of the early cannon. About 1450, however, powder makers
began to "corn" the powder. That is, they formed it into larger
grains, with a resulting increase in the velocity of the shot. It was
"corned" in fine grains for small arms and coarse for cannon.
Making corned powder was fairly simple. The three ingredients were
pulverized and mixed, then compressed into cakes which were cut into
"corns" or grains. Rolling the grains in a barrel polished off the
corners; removing the dust essentially completed the manufacture. It
has always been difficult, however, to make powder twice alike and
keep it in condition, two factors which helped greatly to make gunnery
an "art" in the old days. Powder residue in the gun was especially
troublesome, and a disk-like tool (fig. 44) was designed to scrape the
bore. Artillerymen at Castillo de San Marcos complained that the
"heavy" powder from Mexico was especially bad, for after a gun was
fired a few times, the bore was so fouled that cannonballs would no
longer fit. The gunners called loudly for better grade powder from
Spain itself.
How much powder to use in a gun has been a moot question through the
centuries. According to the Spaniard Collado in 1592, the proper
yardstick was the amount of metal in the gun. A legitimate culverin,
for instance, was "rich" enough in metal to take as much powder as the
ball weighed. Thus, a 30-pounder culverin would get 30 pounds of
powder. Since a 60-pounder battering cannon, however, had in
proportion a third less metal than the culverin, the charge must also
be reduced by a third--to 40 pounds!
[Illustration: Figure 16--GUNPOWDER. Black powder (above) is a
mechanical mixture; modern propellants are chemical compounds.]
Other factors had to be taken into account, such as whether the powder
was coarse-or fine-grained; and a short gun got less powder than a
long one. The bore length of a legitimate culverin, said Collado, was
30 calibers (30 times the bore diameter), so its powder charge was the
same as the weight of the ball. If the gunner came across a culverin
only 24 calibers long, he must load this piece with only 24/30 of the
ball's weight. Collado's _pasavolante_ had a tremendous length of some
40 calibers and fired a 6- or 7-pound lead ball. Because it had plenty
of metal "to resist, and the length to burn" the powder, it was
charged with the full weight of the ball in fine powder, or
three-fourths as much with cannon powder. The lightest charge seems to
have been for the pedrero, which fired a stone ball. Its charge was a
third of the stone's weight.
In later years, powder charges lessened for all guns. English velocity
tables of the 1750's show that a 9-pounder charged with 2-1/4 pounds
of powder might produce its ball at a rate of 1,052 feet per second.
By almost tripling the charge, the velocity would increase about half.
But the increase did not mean the shot hit the target 50 percent
harder, for the higher the velocity, the greater was the air
resistance; or as Mueller phrased it: "a great quantity of Powder does
not always produce a greater effect." Thus, from two-thirds the ball's
weight, standard charges dropped to one-third or even a quarter; and
by the 1800's they became even smaller. The United States manual of
1861 specified 6 to 8 pounds for a 24-pounder siege gun, depending on
the range; a Columbiad firing 172-pound shot used only 20 pounds of
powder. At Fort Sumter, Gillmore's rifles firing 80-pound shells used
10 pounds of powder. The rotating band on the rifle shell, of course,
stopped the gases that had slipped by the loose-fitting cannonball.
Black powder was, and is, both dangerous and unstable. Not only is it
sensitive to flame or spark, but it absorbs moisture from the air. In
other words, it was no easy matter to "keep your powder dry." During
the middle 1700's, Spaniards on a Florida river outpost kept powder in
glass bottles; earlier soldiers, fleeing into the humid forest before
Sir Francis Drake, carried powder in _peruleras_--stoppered,
narrow-necked pitchers.
As for magazines, a dry magazine was just about as important as a
shell-proof one. Charcoal and chloride of lime, hung in containers
near the ceiling, were early used as dehydrators, and in the
eighteenth century standard English practice was to build the floor 2
feet off the ground and lay stone chips or "dry sea coals" under the
flooring. Side walls had air holes for ventilation, but screened to
prevent the enemy from letting in some small animal with fire tied to
his tail. Powder casks were laid on their sides and periodically
rolled to a different position; "otherwise," explains a contemporary
expert, "the salt petre, being the heaviest ingredient, will descend
into the lower part of the barrel, and the powder above will lose much
of its goodness."
[Illustration: Figure 17--SPANISH POWDER BUCKET (c. 1750).]
In the dawn of artillery, loose powder was brought to the gun in a
covered bucket, usually made of leather. The loader scooped up the
proper amount with a ladle (fig. 44), and inserted it into the gun. He
could, by using his experienced judgment, put in just enough powder to
give him the range he wanted, much as our modern artillerymen
sometimes use only a portion of their charge. After Gustavus Adolphus
in the 1630's, however, powder bags came into wide use, although
English gunners long preferred to ladle their powder. The powder
bucket or "passing box" of course remained on the scene. It was
usually large enough to hold a pair of cartridge bags.
The root of the word cartridge seems to be "carta," meaning paper. But
paper was only one of many materials such as canvas, linen, parchment,
flannel, the "woolen stuff" of the 1860's, and even wood. Until the
advent of the silk cartridge, nothing was entirely satisfactory. The
materials did not burn completely, and after several rounds it was
mandatory to withdraw the unburnt bag ends with a wormer (fig. 44),
else they accumulated to the point where they blocked the vent or
"touch hole" by which the piece was fired. Parchment bags shriveled up
and stuck in the vent, purpling many a good gunner's face.
PRIMERS
When the powder bag came into use, the gunner had to prick the bag
open so the priming fire from the vent could reach the charge. The
operation was accomplished simply enough by plunging the gunner's pick
into the vent far enough to pierce the bag. Then the vent was primed
with loose powder from the gunner's flask. The vent prime, which was
not much improved until the nineteenth century, was a trick learned
from the fourteenth century Venetians. There were numerous tries for
improvement, such as the powder-filled tin tube of the 1700's, the
point of which pierced the powder bag. But for all of them, the slow
match had to be used to start the fire train.
[Illustration: Figure 18--LINSTOCKS.]
Before 1800, the slow match was in universal use for setting off the
charge. The match was usually a 3-strand cotton rope, soaked in a
solution of saltpeter and otherwise chemically treated with lead
acetate and lye to burn very slowly--about 4 or 5 inches an hour. It
was attached to a linstock (fig. 18), a forked stick long enough to
keep the cannoneer out of the way of the recoil.
Chemistry advances, like the isolation of mercury fulminate in 1800,
led to the invention of the percussion cap and other primers. On many
a battleground you may have picked up a scrap of twisted wire--the
loop of a friction primer. The device was a copper tube (fig. 19)
filled with powder. The tube went into the vent of the cannon and
buried its tip in the powder charge. Near the top of this tube was
soldered a "spur"--a short tube containing a friction composition
(antimony sulphide and potassium chlorate). Lying in the composition
was the roughened end of a wire "slider." The other end of the slider
was twisted into a loop for hooking to the gunner's lanyard. It was
like striking a match: a smart pull on the lanyard, and the rough
slider ignited the composition. Then the powder in the long tube began
to burn and fired the charge in the cannon. Needless to say, it
happened faster than we can tell it!
[Illustration: Figure 19--FRICTION PRIMER.]
The percussion primer was even more simple: a "quill tube," filled
with fine powder, fitted into the vent. A fulminate cap was glued to
the top of the tube. A pull of the lanyard caused the hammer of the
cannon to strike the cap (just like a little boy's cap pistol) and
start the train of explosions.
Because the early methods of priming left the vent open when the
cannon fired, the little hole tended to enlarge. Many cannon during
the 1800's were made with two vents, side by side. When the first one
wore out, it was plugged, and the second vent opened. Then, to stop
this "erosion," the obturating (sealing) primer came into use. It was
like the common friction primer, but screwed into and sealed the vent.
Early electric primers, by the way, were no great departure from the
friction primer; the wires fired a bit of guncotton, which in turn
ignited the powder in the primer tube.
MODERN USE OF BLACK POWDER
Aside from gradual improvement in the formula, no great change in
powder making came until 1860, when Gen. Thomas J. Rodman of the U. S.
Ordnance Department began to tailor the powder to the caliber of the
gun. The action of ordinary cannon powder was too sudden. The whole
charge was consumed before the projectile had fairly started on its
way, and the strain on the gun was terrific. Rodman compressed powder
into disks that fitted the bore of the gun. The disks were an inch or
two thick, and pierced with holes. With this arrangement, a minimum of
powder surface was exposed at the beginning of combustion, but as the
fire ate the holes larger (compare fig. 20f), the burning area
actually increased, producing a greater volume of gas as the
projectile moved forward. Rodman thus laid the foundation for the
"progressive burning" pellets of modern powders (fig. 20).
[Illustration: Figure 20--MODERN GANNON POWDER. A powder grain has the
characteristics of an explosive only when it is confined. Modern
_propellants_ are low explosives (that is, relatively slow burning),
but _projectiles_ may be loaded with high explosive, a--Flake,
b--Strip, c--Pellet, d--Single perforation, e--Standard,
7-perforation, f--Burning grain of 7-perforation type. Ideally, the
powder grain should burn progressively, with continuously increasing
surface, the grain being completely consumed by the time the
projectile leaves the bore, g--Walsh grain.]
For a number of reasons General Rodman did not take his "perforated
cake cartridge" beyond the experimental stage, and his "Mammoth"
powder, such a familiar item in the powder magazines of the latter
1800's, was a compromise. As a block of wood burns steadier and longer
than a quick-blazing pile of twigs, so the 3/4-inch grains of mammoth
powder gave a "softer" explosion, but one with more "push" and more
uniform pressure along the bore of the gun.
It was in the second year of the Civil War that Alfred Nobel started
the manufacture of nitroglycerin explosives in Europe. Smokeless
powders came into use, the explosive properties of picric acid were
discovered, and melanite, ballistite, and cordite appeared in the last
quarter of the century, so that by 1890 nitrocellulose and
nitroglycerin-base powders had generally replaced black powder as a
propellant.
Still, black powder had many important uses. Its sensitivity to flame,
high rate of combustion, and high temperature of explosion made it a
very suitable igniter or "booster," to insure the complete ignition of
the propellant. Further, it was the main element in such modern
projectile fuzes as the ring fuze of the U. S. Field Artillery, which
was long standard for bursts shorter than 25 seconds. This fuze was in
the nose of the shell and consisted essentially of a plunger, primer,
and rings grooved to hold a 9-inch train of compressed black powder.
To set the fuze, the fuze man merely turned a movable ring to the
proper time mark. Turning the zero mark toward the channel leading to
the shell's bursting charge shortened the burning distance of the
train, while turning zero away from the channel, of course, did the
opposite. When the projectile left the gun, the shock made the plunger
ignite the primer (compare fig. 42e) and fire the powder train, which
then burned for the set time before reaching the shell charge. It was
a technical improvement over the tubular sheet-iron fuze of the
Venetians, but the principle was about the same.
[Illustration: Figure 21--MODERN POWDER TRAIN FUZE.]
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 trajectory--the 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 likewise 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 _canones de pedreros_. All the classes of
pieces are different in range, manufacture and design. Even the method
of charging them is different."
[Illustration: Figure 22--TRAJECTORIES. 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.
[Illustration: Figure 23--SIXTEENTH 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, a--Culverin (Class 1). b--Cannon (Class 2). c--Pedrero
(Class 3). d--Mortar (Class 3).]
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.
_Sixteenth century Spanish cannon of the first class_
Name of Weight of Length Range in yards Popular
gun ball of gun Point- Maximum caliber
(pounds) (in calibers) blank
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 9-pounder
saker 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 to 32 1,742 6,666 24-pounder
culverin.
30, 40, 50
Culebrina
real 24 to 40 30 to 32 32-pounder
culverin royal.
Doble
culebrina 40 and up 30 to 32 48-pounder
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 _coulevrine_ 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_
Caliber Length Weight Weight Powder
(inches) of gun of shot charge
Ft. In. (pounds) (pounds) (pounds)
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 _aspide_ 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 walls than any other small caliber gun, and the
combination of length and weight permitted an unusually heavy
charge--as 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 gun was a football field's length farther than either the
falcon or demisaker.
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