Chapter II: Part 2

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.

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!

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).

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.

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 _cañones de pedreros_. All the classes of pieces are different in range, manufacture and design. Even the method of charging them is different."

_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.

_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.
Falcón 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 _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 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.

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 _drajón_, 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 Translation
(pounds)

Quarto cañon 9 to 12 Quarter-cannon.
Tercio cañon 16 Third-cannon.
Medio cañon 24 Demicannon.
Cañon de abatir 32 Siege cannon.
Doble cañon 48 Double cannon.
Cañon de batería 60 Battering cannon.
Serpentino Serpentine.
Quebrantamuro or lombarda 70 to 90 Wallbreaker or lombard.
Basilisco 80 and up Basilisk.

The second class of guns were the only ones properly called "cannon" 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.

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 guns--all 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 9 6-1/2 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) 7 5 3-1/2
Cañon reforzado (reinforced cannon) 8 5-1/2 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.

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_

------------------------+-------------------------+---------------------
¦ Thickness of bore wall ¦
¦ in 8ths of the caliber ¦
Spanish Guns +-------+---------+-------+ 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.

SMOOTHBORES OF THE LATER PERIOD

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.

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.

GARRISON AND SHIP GUNS

Cannon for permanent fortifications were of various sizes and calibers, depending upon the terrain that had to be defended. At Castillo de San Marcos, for instance, the strongest armament was on the water front; lighter guns were on the land sector, an area naturally protected by the difficult terrain existing in the colonial period.

Before the Castillo was completed, guns were mounted only in the bastions or projecting corners of the fort. A 1683 inventory clearly shows that heaviest guns were in the San Agustín, or southeastern bastion, commanding not only the harbor and its entrance but the town of St. Augustine as well San Pablo, the northwestern bastion, overlooked the land approach to the Castillo and the town gate; and, though its armament was lighter, it was almost as numerous as that in San Agustín. Bastion San Pedro to the southwest was within the town limits, and its few light guns were a reserve for San Pablo. The watchtower bastion of San Carlos overlooked the northern marshland and the harbor; its armament was likewise small. The following list details the variety and location of the ordnance:

_Cannon mounted at Castillo de San Marcos in 1683_

Location No. Caliber Class Metal Remarks

In the bastion
of San Agustín
1 40-pounder Cannon Bronze Carriage battered.
1 18-pounder do do New carriage.
2 16-pounder do Iron Old carriages,
wheels bad.
1 12-pounder do Bronze New carriage.
1 12-pounder do Iron do.
1 8-pounder do Bronze Old carriage.
1 7-pounder do Iron Carriage bad.
1 4-pounder do do New carriage.
1 3-pounder do Bronze do.

In the bastion
of San Pablo
1 16-pounder Demicannon Iron Old carriage.
1 10-pounder Demiculverin Bronze do.
2 9-pounder Cannon Iron do.
1 7-pounder Demiculverin Bronze do.
1 7-pounder Cannon Iron Carriage bad.
1 5-pounder do do New carriage.

In the bastion
of San Pedro
1 9-pounder Cannon Iron Old carriage.
2 7-pounder do do Carriage bad.
2 5-pounder do do do.
1 4-pounder do Bronze Old carriage.

In the bastion
of San Carlos
1 10-pounder Cannon Iron Old carriage.
1 5-pounder do do New carriage.
1 5-pounder do Bronze Good carriage.
1 2-pounder do Iron New carriage.

The total number of Castillo guns in service at this date was 27, but there were close to a dozen unmounted pieces on hand, including a pair of pedreros. The armament was gradually increased to 70-odd guns as construction work on the fort made additional space available, and as other factors warranted more ordnance. Below is a summary of Castillo armament through the years:

_Armament of Castillo de San Marcos, 1683-1834_

Kind 1683 1706 1740 1763 1765 1812 1834
of gun Iron Iron Iron Iron Iron Iron Iron
Bronze Bronze Bronze Bronze Bronze Bronze Bronze

2-pounder 1 .. .. ** .. .. .. .. .. .. .. .. .. ..
3-pounder .. 1 .. ** 2 3 .. .. .. .. .. .. .. ..
4-pounder 1 1 * ** 5 1 .. .. .. .. 1 .. .. ..
5-pounder 4 1 * ** 15 1 .. .. .. .. .. .. .. ..
6-pounder .. .. * ** 5 .. .. .. .. 1 .. .. 3 ..
7-pounder 4 1 * ** 5 2 .. .. .. .. .. .. .. ..
8-pounder .. 1 * ** 11 1 5 11 .. .. 1 .. .. ..
3-1/2 in.
carronade .. .. * ** .. .. .. .. .. .. 4 .. .. ..
9-pounder 3 .. * ** .. .. .. .. .. .. .. .. .. ..
10-pounder 1 1 * ** .. .. 6 .. .. .. .. .. .. ..
12-pounder 1 1 * ** .. .. 13 .. 7 .. 2 .. .. ..
15-pounder .. .. .. ** 6 .. .. .. .. .. .. .. .. ..
16-pounder 3 .. .. ** .. .. 2 1 .. .. 8 .. .. ..
18-pounder .. 1 .. .. 4 1 7 .. .. .. .. .. 4 ..
24-pounder .. .. .. .. 2 .. 7 .. 32 .. 10 .. 5 ..
33-pounder .. .. .. .. .. 1 .. .. .. .. .. .. .. ..
36-pounder .. .. .. 1 .. .. .. 1 .. .. .. .. .. ..
40-pounder .. 1 .. .. .. .. .. .. .. .. .. .. .. ..
24-pounder
field
howitzer .. .. .. .. .. .. .. .. .. .. .. .. 2 2
6-in.
howitzer .. .. .. .. .. .. .. .. .. .. .. 2 .. 2
8-in.
howitzer .. .. .. .. .. .. .. .. .. 2 .. .. .. ..
Small
mortar .. .. .. .. .. .. .. 18 .. 20 .. .. .. ..
6-in.
mortar .. .. .. .. .. .. .. .. .. .. .. 1 .. 1
10-in.
mortar .. .. .. .. .. .. .. .. .. .. .. .. .. 1
Large
mortar .. .. .. .. .. .. .. 6 .. 1 .. .. .. ..
Stone
mortar 2 .. .. .. .. .. .. .. .. .. .. 3 .. ..

Total 20 9 26 9 55 10 40 37 39 24 26 8 14 6

Grand total 29 35 65 77 63 34 20

* 26 guns from 4- to 10-pounders

** 8 guns from 2- to 16-pounders

This tabulation reflects contemporary conditions quite clearly. The most serious invasions of Spanish Florida took place during the first half of the eighteenth century, precisely the time when the Castillo armament was strongest. While most of the guns were in battery condition, the table does have some pieces rated only fair and may also include a few unserviceables. Colonial isolation meant that ordnance often served longer than the normal 1,200-round life of an iron piece. A usual failure was the development of cracks around the vent or in the bore. Sometimes a muzzle blew off. The worst casualties of the 1702 siege came from the bursting of an iron 16-pounder which killed four and seriously wounded six men. At that period, incidentally, culverins were the only guns with the range to reach the harbor bar some 3,000 yards away.

Although when the Spanish left Florida to Britain in 1763 they took serviceable cannon with them, two guns at Castillo de San Marcos National Monument today appear to be seventeenth century Spanish pieces. Most of the 24- and 32-pounder garrison cannon, however, are English-founded, after the Armstrong specifications of the 1730's, and were part of the British armament during the 1760's. Amidst the general confusion and shipping troubles that attended the British evacuation in 1784, some ordnance seems to have been left behind, to remain part of the defenses until the cession to the United States in 1821.

The Castillo also has some interesting United States guns, including a pair of early 24-pounder iron field howitzers (c. 1777-1812). During the 1840's the United States modernized Castillo defenses by constructing a water battery in the moat behind the sea wall. Many of the guns for that battery are extant, including 8-inch Columbiads, 32-pounder cannon, 8-inch seacoast and garrison howitzers. St. Augustine's Plaza even boasts a converted 32-pounder rifle.

Garrison and ship carriages were far different from field, siege, and howitzer mounts, while mortar beds were in a separate class entirely. Basic proportions for the carriage were obtained by measuring (1) the distance from trunnion to base ring of the gun, (2) the diameter of the base ring, and (3) the diameter of the second reinforce ring. The result was a quadrilateral figure that served as a key in laying out the carriage to fit the gun. Cheeks, or side pieces, of the carriage were a caliber in thickness, so the bigger the gun, the more massive the mount.

A 24-pounder cheek would be made of timber about 6 inches thick. The Spaniards often used mahogany. At Jamestown, in the early 1600's, Capt. John Smith reported the mounting of seven "great pieces of ordnance upon new carriages of cedar," and the French colonials also used this material. British specifications in the mid-eighteenth century called for cheeks and transoms of dry elm, which was very pliable and not likely to split; but some carriages were made of young oak, and oak was standard for United States garrison carriages until it was replaced by wrought-iron after the Civil War.

For a four-wheeled English carriage of 1750, height of the cheek was 4-2/3 diameters of the shot, unless some change in height had to be made to fit a gun port or embrasure. To prevent cannon from pushing shutters open when the ship rolled in a storm, lower tier carriages let the muzzle of the gun, when fully elevated, butt against the sill over the gun port.

On the eighteenth century Spanish garrison carriage (fig. 28), no bolts were threaded; all were held either by a key run through a slot in the foot of the bolt, or by bradding the foot over a decorative washer. Compared with American mounts of the same type (figs. 30 and 31), the Spanish carriage was considerably more complicated, due partly to the greater amount of decorative ironwork and partly to the design of the wooden parts which, with their carefully worked mortises, required a craftsman's skill. The cheek of the Spanish carriage was a single great plank. English and American construction called for a built-up cheek of several planks, cleverly jogged or mortised together to prevent starting under the strain of firing.

Müller furnished specifications for building truck (four-wheeled) carriages for 3- to 42-pounders. Aboard ship, of course, the truck carriage was standard for almost everything except the little swivel guns and the mortars.

Carriage trucks (wheels), unless they were made of cast iron, had iron thimbles or bushings driven into the hole of the hub, and to save the wood of the axletree, the spindle on which the wheel revolved was partly protected by metal. The British put copper on the _bottom_ of the spindle; Spanish and French designers put copper on the _top_, then set iron "axletree bars" into the bottom. These bars strengthened the axletree and resisted wear at the spindle.

A 24-pounder fore truck was 18 inches in diameter. Rear trucks were 16 inches. The difference in size compensated for the slope in the gun platform or deck--a slope which helped to check recoil. Aboard ship, where recoil space was limited, the "kick" of the gun was checked by a heavy rope called a breeching, shackled to the side of the vessel (see fig. 11). Ship carriages of the two-or four-wheel type (fig. 31), were used through the War between the States, and there was no great change until the advent of automatic recoil mechanisms made a stationary mount possible.

With garrison carriages, however, changes came much earlier. In 1743, Fort William on the Georgia coast had a pair of 18-pounders mounted upon "curious moving Platforms" which were probably similar to the traversing platforms standardized by Gribeauval in the latter part of the century. United States forts of the early 1800's used casemate and barbette carriages (fig. 10) of the Gribeauval type, and the traversing platforms of these mounts made training (aiming the gun right or left) comparatively easy.

Training the old truck carriage had been heavy work for the handspikemen, who also helped to elevate or depress the gun. Maximum elevation or depression was about 15° each way--about the same as naval guns used during the Civil War. If one quoin was not enough to secure proper depression, a block or a second quoin was placed below the first. But before the gunner depressed a smoothbore below zero elevation, he had to put either a wad or a grommet over the ball to keep it from rolling out.

Ship and garrison cannon were not moved around on their carriages. If the gun had to be taken any distance, it was dismounted and chained under a sling wagon or on a "block carriage," the big wheels of which easily rolled over difficult terrain. It was not hard to dismount a gun: the keys locking the cap squares were removed, and then the gin was rigged and the gun hoisted clear of the carriage.

A typical garrison or ship cannon could fire any kind of projectile, but solid shot, hot shot, bombs, grape, and canister were in widest use. These guns were flat trajectory weapons, with a point-blank range of about 300 yards. They were effective--that is, fairly accurate--up to about half a mile, although the maximum range of guns like the Columbiad of the nineteenth century, when elevation was not restricted by gun port confines, approached the 4-mile range claimed by the Spanish for the sixteenth century culverin. The following ranges of United States ordnance in the 1800's are not far different from comparable guns of earlier date.

_Ranges of United States smoothbore garrison guns of 1861_

Caliber Elevation Range in yards

18-pounder siege and garrison 5° 0" 1,592
24-pounder siege and garrison 5° 0" 1,901
32-pounder seacoast 5° 0" 1,922
42-pounder seacoast 5° 0" 1,955
8-inch Columbiad 27°30" 4,812
10-inch Columbiad 39°15" 5,654
12-inch Columbiad 39° 0" 5,506

_Ranges of United States naval smoothbores of 1866_

Caliber Point-blank range Elevation Range in yards
in yards
32-pounder of 42 cwt 313 5° 1,756
8-inch of 63 cwt 330 5° 1,770
IX-inch shell gun 350 15° 3,450
X-inch shell gun 340 11° 3,000
XI-inch shell gun 295 15° 2,650
XV-inch shell gun 300 7° 2,100

_Ranges of United States naval rifles in 1866_

Caliber Elevation Range in yards

20-pounder Parrott 15° 4,400
30-pounder Parrott 25° 6,700
100-pounder Parrott 25° 7,180

In accuracy and range the rifle of the 1860's far surpassed the smoothbores, but such tremendous advances were made in the next few decades with the introduction of new propellants and steel guns that the performances of the old rifles no longer seem remarkable. In the eighteenth century, a 24-pounder smoothbore could develop a muzzle velocity of about 1,700 feet per second. The 12-inch rifled cannon of the late 1800's had a muzzle velocity of 2,300 foot-seconds. In 1900, the Secretary of the Navy proudly reported that the new 12-inch guns for _Maine_-class battleships produced a muzzle velocity of 2,854 foot-seconds, using an 850-pound projectile and a charge of 360 pounds of smokeless powder. Such statistics elicit a chuckle from today's artilleryman.

SIEGE CANNON

Field counterpart of the garrison cannon was the siege gun--the "battering cannon" of the old days, mounted upon a two-wheeled siege or "traveling" carriage that could be moved about in field terrain. Whereas the purpose of the garrison cannon was to destroy the attacker and his matériel, the siege cannon was intended to destroy the fort. Calibers ranged from 3- to 42-pounders in eighteenth century English tables, but the 18- and 24-pounders seem to have been the most widely used for siege operations.

The siege carriage closely resembled the field gun carriage, but was much more massive, as may be seen from these comparative figures drawn from eighteenth century English specifications:

24-pounder 24-pounder
field carriage siege carriage

9 feet long Length of cheek 13 feet.
4.5 inches Thickness of cheek 5.8 inches.
50 inches Wheel diameter 58 inches.
6x8x68 inches Axletree 7x9x81 inches.

Heavy siege guns were elevated with quoins, and elevation was restricted to 12° or less, which was about the same as United States siege carriages permitted in 1861. It was considered ample for these flat trajectory pieces.

Both field and siege carriages were pulled over long distances by lifting the trail to a horse-or ox-drawn limber; a hole in the trail transom seated on an iron bolt or pintle on the two-wheeled limber. Some late eighteenth century field and siege carriages had a second pair of trunnion holes a couple of feet back from the regular holes, and the cannon was shifted to the rear holes where the weight was better distributed for traveling. The United States siege carriage of the 1860's had no extra trunnion holes, but a "traveling bed" was provided where the gun was cradled in position 2 or 3 feet back of its firing position. A well-drilled gun crew could make the shift very rapidly, using a lifting jack, a few rollers, blocks, and chocks. When there was danger of straining or breaking the gun carriage, however, massive block carriages, sling carts, or wagons were used to carry the guns.