Part 3 (1/2)
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 n.o.bel started the manufacture of nitroglycerin explosives in Europe. Smokeless powders came into use, the explosive properties of picric acid were discovered, and melanite, ballist.i.te, 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 sh.e.l.l 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 sh.e.l.l'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 sh.e.l.l charge. It was a technical improvement over the tubular sheet-iron fuze of the Venetians, but the principle was about the same.
[Ill.u.s.tration: 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 sh.e.l.l 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 cla.s.ses, 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 cla.s.s, designed to strike the enemy from long range. The battering cannon (fig. 23b) were second cla.s.s pieces; they were to destroy forts and walls and dismount the enemy's machines. Third cla.s.s guns fired stone b.a.l.l.s to break and sink s.h.i.+ps and defend batteries from a.s.sault; 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 cla.s.ses 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 b.a.l.l.s 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 a.s.saults or s.h.i.+ps and galleys, they made a third cla.s.s of piece, lighter in metal and taking less powder, to fire b.a.l.l.s of stone. These are the commonly called _canones de pedreros_. All the cla.s.ses of pieces are different in range, manufacture and design. Even the method of charging them is different.”
[Ill.u.s.tration: 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 ma.s.sed 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 cla.s.ses of guns. As Collado quaintly phrased it, ”he who ignores the present lecture on this _arte_ will, I a.s.sert, 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.
[Ill.u.s.tration: Figure 23--SIXTEENTH CENTURY SPANISH ARTILLERY. Taken from a 1592 ma.n.u.script, these drawings ill.u.s.trate the three main cla.s.ses of artillery used by Spain during the early colonial period in the New World, a--Culverin (Cla.s.s 1). b--Cannon (Cla.s.s 2). c--Pedrero (Cla.s.s 3). d--Mortar (Cla.s.s 3).]
The first cla.s.s 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 cla.s.s 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 cla.s.s_
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.