From the guns of Queen Elizabeth's time came the 6-, 9-, 12-, 18-,
24-, 32-, and 42-pounder classifications adopted by Cromwell's
government and used by the English well through the eighteenth
century. On the Continent, during much of this period, the French were
acknowledged leaders. Louis XIV (1643-1715) brought several foreign
guns into his ordnance, standardizing a set of calibers (4-, 8-, 12-,
16-, 24-, 32-, and 48-pounders) quite different from Henry II's in the
previous century.
The cannon of the late 1600's was an ornate masterpiece of the
foundryman's art, covered with escutcheons, floral relief, scrolls,
and heavy moldings, the most characteristic of which was perhaps the
banded muzzle (figs. 23b-c, 25, 26a-b), that bulbous bit of
ornamentation which had been popular with designers since the days of
the bombards. The flared or bell-shaped muzzle (figs. 23a, 26c, 27),
did not supplant the banded muzzle until the eighteenth century, and,
while the flaring bell is a usual characteristic of ordnance founded
between 1730 and 1830, some banded-muzzle guns were made as late as
1746 (fig. 26a).
By 1750; however, design and construction were fairly well
standardized in a gun of much cleaner line than the cannon of 1650.
Although as yet there had been no sharp break with the older
traditions, the shape and weight of the cannon in relation to the
stresses of firing were becoming increasingly important to the men who
did the designing.
Conditions in eighteenth century England were more or less typical: in
the 1730's Surveyor-General Armstrong's formulae for gun design were
hardly more than continuations of the earlier ways. His guns were
about 20 calibers long, with these outside proportions:
1st reinforce = 2/7 of the gun's length.
2d reinforce = 1/7 plus 1 caliber.
chase = 4/7 less 1 caliber.
The trunnions, about a caliber in size, were located well forward
(3/7 of the gun's length) "to prevent the piece from kicking up
behind" when it was fired. Gunners blamed this bucking tendency on the
practice of centering the trunnions on the _lower_ line of the bore.
"But what will not people do to support an old custom let it be ever
so absurd?" asked John Müller, the master gunner of Woolwich. In 1756,
Müller raised the trunnions to the _center_ of the bore, an
improvement that greatly lessened the strain on the gun carriage.
[Illustration: Figure 26--EIGHTEENTH CENTURY CANNON, a--Spanish
bronze 24-pounder of 1746. b--French bronze 24-pounder of the early
1700's. c--English iron 6-pounder of the middle 1700's. The 6-pounder
is part of the armament at Castillo de San Marcos.]
[Illustration: Figure 27--SPANISH 24-POUNDER CAST-IRON GUN (1693).
Note the modern lines of this cannon, with its flat breech and slight
muzzle swell.]
The caliber of the gun continued to be the yardstick for "fortification"
of the bore walls:
Vent 16 parts
End of 1st reinforce 14-1/2 do
Beginning of second reinforce 13-1/2 do
End of second reinforce 12-1/2 do
Beginning of chase 11-1/2 do
End of chase 8 do
For both bronze and iron guns, the above figures were the same, but
for bronze, Armstrong divided the caliber into 16 parts; for iron it
was only 14 parts. The walls of an iron gun thus were slightly thicker
than those of a bronze one.
This eighteenth century cannon was a cast gun, but hoops and rings
gave it the built-up look of the barrel-stave bombard, when hoops were
really functional parts of the cannon. Reinforces made the gun look
like "three frustums of cones joined together, so as the lesser base
of the former is always greater than the greatest of the succeeding
one." Ornamental fillets, astragals, and moldings, borrowed from
architecture, increased the illusion of a sectional piece. Tests with
24-pounders of different lengths showed guns from 18 to 21 calibers
long gave generally the best performance, but what was true for the
24-pounder was not necessarily true for other pieces. Why was the
32-pounder "brass battering piece" 6 inches longer than its 42-pounder
brother? John Müller wondered about such inconsistencies and set out
to devise a new system of ordnance for England.
Like many men before him, Müller sought to increase the caliber of
cannon without increasing weight. He managed it in two ways: he
modified exterior design to save on metal, and he lessened the powder
charge to permit shortening and lightening the gun. Müller's guns had
no heavy reinforces; the metal was distributed along the bore in a
taper from powder chamber to muzzle swell. But realizing man's
reluctance to accept new things, he carefully specified the location
and size for each molding on his gun, protesting all the while the
futility of such ornaments. Not until the last half of the next
century were the experts well enough versed in metallurgy and interior
ballistics to slough off all the useless metal.
So, using powder charges about one-third the weight of the projectile,
Müller designed 14-caliber light field pieces and 15-caliber ship
guns. His garrison and battering cannon, where weight was no great
disadvantage, were 18 calibers long. The figures in the table
following represent the principal dimensions for the four types of
cannon--all cast-iron except for the bronze siege guns. The first line
in the table shows the length of the cannon. To proportion the rest of
the piece, Müller divided the shot diameter into 24 parts and used it
as a yardstick. The caliber of the gun, for instance, was 25 parts, or
25/24th of the shot diameter. The few other dimensions--thickness of
the breech, length of the gun before the barrel began its taper,
fortification at vent and chase--were expressed the same way.
-----------------------------------+-------+--------+-------+---------
| Field | Ship | Siege | Garrison
-----------------------------------+-------+--------+-------+---------
Length in calibers | 14 | 15 | 18 | 18
(Other proportions in 24ths of the shot diameter) |
Caliber | 25 | 25 | 25 | 25
Thickness of breech | 14 | 24 | 16 | 24
Length from breech to taper | 39 | 49 | 40 | 49
Thickness at vent | 16 | 25 | 18 | 25
Thickness at muzzle | 8 | 12-1/2 | 9 | 12-1/2
-----------------------------------+-------+--------+-------+---------
The heaviest of Müller's garrison guns averaged some 172 pounds of
iron for every pound of the shot, while a ship gun weighed only 146,
less than half the iron that went into the sixteenth century cannon.
And for a seafaring nation such as England, these were important
things. Perhaps the opposite table will give a fair idea of the
changes in English ordnance during the eighteenth century. It is based
upon John Müller's lists of 1756; the "old" ordnance includes cannon
still in use during Müller's time, while the "new" ordnance is
Müller's own.
Windage in the English gun of 1750 was about 20 percent greater than
in French pieces. The English ratio of shot to caliber was 20:21;
across the channel it was 26:27. Thus, an English 9-pounder fired a
4.00-inch ball from a 4.20-inch bore; the French 9-pounder ball was
4.18 inches and the bore 4.34.
The English figured greater windage was both convenient and
economical: windage, said they, ought to be just as thick as the metal
in the gunner's ladle; standing shot stuck in the bore and unless it
could be loosened with the ladle, had to be fired away and lost. John
Müller brushed aside such arguments impatiently. With a proper wad
over the shot, no dust or dirt could get in; and when the muzzle was
lowered, said Müller, the shot "will roll out of course." Besides,
compared with increased accuracy, the loss of a shot was trifling.
Furthermore, with less room for the shot to bounce around the bore,
the cannon would "not be spoiled so soon." Müller set the ratio of
shot to caliber as 24:25.
_Calibers and lengths of principal eighteenth century English cannon_
---------+-----------+---------------------+-----------+----------+
Caliber | Field | Ship | Siege | Garrison |
+-----------+----------+----------+-----------+----------+
| Iron | Bronze | Iron | Bronze | Iron |
+-----+-----+----+-----+-----+----+-----+-----+----+-----+
(pounder)| Old | New | Old| New | Old | New| Old | New | Old| New |
---------+-----+-----+----+-----+-----+----+-----+-----+----+-----+
1-1/2 | | | | | | | 6'0"| | | |
3 |3'6" |3'3" | |3'6" | 4'6"|3'6"| 7'0"| |4'6"| 4'2"|
4 | | | | | 6'0"| | | | | |
6 |4'6" |4'1" |8'0"|4'4" | 7'0"|4'4"| 8'0"| |6'6"| 5'3"|
9 | |4'8" | |5'0" | 7'0"|5'0"| 9'0"| |7'0"| 6'0"|
12 |5'0" |5'1" |9'0"|5'6" | 9'0"|5'6"| 9'0"| 6'7"|8'0"| 6'7"|
18 | |5'10"| |6'4" | 9'0"|6'4"| 9'6"| 8'4"|9'0"| 7'6"|
24 |5'6" |6'5" |9'6"|7'0" | 9'0"|7'0"| 9'6"| 8'4"|9'0"| 8'4"|
32 | | | |7'6" | 9'6"|7'6"|10'0"| 9'2"|9'6"| 9'2"|
36 | | | |7'10"| | | | 9'6"| | |
42 | | |9'6"|8'4" |10'0"|8'4"| 9'6"|10'0"| |10'0"|
48 | | | |8'6" | |8'6"| |10'6"| | |
---------+-----+-----+----+-----+-----+----+-----+-----+----+-----+
In the 1700's cast-iron guns became the principal artillery afloat and
ashore, yet cast bronze was superior in withstanding the stresses of
firing. Because of its toughness, less metal was needed in a bronze
gun than in a cast-iron one, so in spite of the fact that bronze is
about 20 percent heavier than iron, the bronze piece was usually the
lighter of the two. For "position" guns in permanent fortifications
where weight was no disadvantage, iron reigned supreme until the
advent of steel guns. But non-rusting bronze was always preferable
aboard ship or in seacoast forts.
Müller strongly advocated bronze for ship guns. "Notwithstanding all
the precautions that can be taken to make iron Guns of a sufficient
strength," he said, "yet accidents will sometimes happen, either by
the mismanagement of the sailors, or by frosty weather, which renders
iron very brittle." A bronze 24-pounder cost £156, compared with £75
for the iron piece, but the initial saving was offset when the gun
wore out. The iron gun was then good for nothing except scrap at a
farthing per pound, while the bronze cannon could be recast "as often
as you please."
In 1740, Maritz of Switzerland made an outstanding contribution to the
technique of ordnance manufacture. Instead of hollow casting (that is,
forming the bore by casting the gun around a core), Maritz cast the
gun solid, then drilled the bore, thus improving its uniformity. But
although the bore might be drilled quite smooth, the outside of a
cast-iron gun was always rough. Bronze cannon, however, could be put
in the lathes to true up even the exterior. While after 1750 the
foundries seldom turned out bronze pieces as ornate as the Renaissance
culverins, a few decorations remained and many guns were still
personalized with names in raised letters on the gun. Castillo de San
Marcos has a 4-pounder "San Marcos," and, indeed, saints' names were
not uncommon on Spanish ordnance. Other typical names were _El
Espanto_ (The Terror), _El Destrozo_ (The Destroyer), _Generoso_
(Generous), _El Toro_ (The Bull), and _El Belicoso_ (The Quarrelsome
One).
In some instances, decoration was useful. The French, for instance, at
one time used different shapes of cascabels to denote certain
calibers; and even a fancy cascabel shaped like a lion's head was
always a handy place for anchoring breeching tackle or maneuvering
lines. The dolphins or handles atop bronze guns were never merely
ornaments. Usually they were at the balance point of the gun; tackle
run through them and hooked to the big tripod or "gin" lifted the
cannon from its carriage.