Part 8 (1/2)

EXPLOSIVE Sh.e.l.lS

The word ”bomb” comes to us from the French, who derived it from the Latin. But the Romans got it originally from the Greek _bombos_, meaning a deep, hollow sound. ”Bombard” is a derivation. Today bomb is p.r.o.nounced ”balm,” but in the early days it was commonly p.r.o.nounced ”b.u.m.” The modern equivalent of the ”b.u.m” is an HE sh.e.l.l.

The first recorded use of explosive sh.e.l.ls was by the Venetians in 1376. Their bombs were hemispheres of stone or bronze, joined together with hoops and exploded by means of a primitive powder fuze. Sh.e.l.ls filled with explosive or incendiary mixtures were standard for mortars, after 1550, but they did not come into general use for flat-trajectory weapons until early in the nineteenth century, whereafter the term ”sh.e.l.l” gradually won out over ”bomb.”

In any event, this projectile was one of the most effective ever used in the smoothbore against earthworks, buildings, and for general bombardment. A delayed action sh.e.l.l, diabolically timed to roll amongst the ranks with its fuze burning, was calculated to ”disorder the stoutest men,” since they could not know at what awful instant the bomb would burst.

A bombsh.e.l.l was simply a hollow, cast-iron sphere. It had a single hole where the powder was funneled in--full, but not enough to pack too tightly when the fuze was driven in. Until the 1800's, the larger bombs were not always smooth spheres, but had either a projecting neck, or collar, for the fuze hole or a pair of rings at each side of the hole for easier handling (fig. 41). In later years, however, such projections were replaced by two ”ears,” little recesses beside the fuze hole. A pair of tongs (something like ice tongs) seized the sh.e.l.l by the ears and lifted it up to the gun bore.

During most of the eighteenth century, sh.e.l.ls were cast thicker at the base than at the fuze hole on the theory that they were (1) better able to resist the shock of firing from the cannon and (2) more likely to fall with the heavy part underneath, leaving the fuze uppermost and less liable to extinguishment. Muller scoffed at the idea of ”choaking” a fuze, which, he said, burnt as well in water as in any other element. Furthermore, he preferred to use sh.e.l.ls ”everywhere equally thick, because they would then burst into a greater number of pieces.” In later years, the sh.e.l.ls were scored on the interior to ensure their breaking into many fragments.

FUZES

[Ill.u.s.tration: Figure 42--NINETEENTH CENTURY PROJECTILE FUZES.

a--Cross-section of Bormann fuze, b--Top of Bormann fuze, c--Wooden fuze for spherical sh.e.l.l, d--Wood-and-paper fuze for spherical sh.e.l.l, e--Percussion fuze.]

The eighteenth century fuze was a wooden tube several inches long, with a powder composition tamped into its hole much like the nineteenth century fuze (fig. 42c). The hole was only a quarter of an inch in diameter, but the head of the fuze was hollowed out like a cup, and ”mealed” (fine) powder, moistened with ”spirits of wine”

(alcohol), was pressed into the hollow to make a larger igniting surface. To time the fuze, a cannoneer cut the cylinder at the proper length with his fuze-saw, or drilled a small hole (G) where the fire could flash out at the right time. Some English fuzes at this period were also made by drawing two strands of a quick match into the hole, instead of filling it with powder composition. The ends of the match were crossed into a sort of rosette at the head of the fuze. Paper caps to protect the powder composition covered the heads of these fuzes and had to be removed before the sh.e.l.l was put into the gun.

Bombs were not filled with powder very long before use, and fuzes were not put into the projectiles until the time of firing. To force the fuze into the hole of the sh.e.l.l, the cannoneer covered the fuze head with tow, put a fuze-setter on it, and hammered the setter with a mallet, ”drifting” the fuze until the head stuck out of the sh.e.l.l only 2/10 of an inch. If the fuze had to be withdrawn, there was a fuze extractor for the job. This tool gripped the fuze head tightly, and turning a screw slowly pulled out the fuze.

Wooden tube fuzes were used almost as long as the spherical sh.e.l.l. A United States 12-inch mortar fuze (fig. 42c), 7 inches long and burning 49 seconds, was much like the earlier fuze. During the 1800's, however, other types came into wide use.

The conical paper-case fuze (fig. 42d), inserted in a metal or wooden plug that fitted the fuze hole, contained composition whose rate of burning was shown by the color of the paper. A black fuze burned an inch every 2 seconds. Red burned 3 seconds, green 4, and yellow 5 seconds per inch. Paper fuzes were 2 inches long, and could be cut shorter if necessary. Since firing a sh.e.l.l from a 24-pounder to burst at 2,000 yards meant a time flight of 6 seconds, a red fuze would serve without cutting, or a green fuze could be cut to 1-1/2 inches.

Sea-coast fuzes of similar type were used in the 15-inch Rodmans until these big smoothbores were finally discarded sometime after 1900.

The Bormann fuze (fig. 42a), the quickest of the oldtimers to set, was used for many years by the U. S. Field Artillery in spherical sh.e.l.l and shrapnel. Its pewter case, which screwed into the sh.e.l.l, contained a time ring of powder composition (A). Over this ring the top of the fuze case was marked in seconds. To set the fuze, the gunner merely had to cut the case at the proper mark--at four for 4 seconds, three for 3 seconds, and so on--to expose the ring of powder to the powder blast of the gun. The ring burned until it reached the zero end and set off the fine powder in the center of the case; the powder flash then blew out a tin plate in the bottom of the fuze and ignited the sh.e.l.l charge. Its short burning time (about 6 seconds) made the Bormann fuze obsolete as field gun ranges increased. The main trouble with this fuze, however, was that it did not always ignite!

The percussion fuze was an extremely important development of the nineteenth century, particularly for the long-range rifles. The shock of impact caused this fuze to explode the sh.e.l.l at almost the instant of striking. Percussion fuzes were made in two general types: the front fuze, for the nose of an elongated projectile; and the base fuze, at the center of the projectile base. The base fuze was used with armor-piercing projectiles where it was desirable to have the sh.e.l.l penetrate the target for some distance before bursting. Both types were built on the same principles.

A Hotchkiss front percussion fuze (fig. 42e) had a bra.s.s case which screwed into the sh.e.l.l. Inside the case was a plunger (A) containing a priming charge of powder, topped with a cap of fulminate. A bra.s.s wire at the base of the plunger was a safety device to keep the cap away from a sharp point at the top of the fuze until the sh.e.l.l struck the target. When the gun was fired, the shock of discharge dropped a lead plug (B) from the base of the fuze into the projectile cavity, permitting the plunger to drop to the bottom of the fuze and rest there, held by the spread wire, while the sh.e.l.l was in flight. Upon impact, the plunger was thrown forward, the cap struck the point and ignited the priming charge, which in turn fired the bursting charge of the sh.e.l.l.

SCATTER PROJECTILES

When one of our progenitors wrathfully seized a handful of pebbles and flung them at the flock of birds in his garden, he discovered the principle of the scatter projectile. Perhaps its simplest application was in the stone mortar (fig. 43). For this weapon, round stones about the size of a man's fist (and, by 1750, hand grenades) were dumped into a two-handled basket and let down into the bore. This primitive charge was used at close range against personnel in a fortification, where the effect of the descending projectiles would be uncommonly like a short but severe barrage of over-sized hailstones. There were 6,000 stones in the ammunition inventory for Castillo de San Marcos in 1707.

[Ill.u.s.tration: Figure 43--SPANISH 16-INCH PEDRERO (1788). This mortar fired baskets of stones.]

One of the earliest kinds of scatter projectiles was case shot, or canister, used at Constantinople in 1453. The name comes from its case, or can, usually metal, which was filled with sc.r.a.p, musket b.a.l.l.s, or slugs (fig. 41). Somewhat similar, but with larger iron b.a.l.l.s and no metal case, was grape shot, so-called from the grape-like appearance of the cl.u.s.tered b.a.l.l.s. A stand of grape in the 1700's consisted of a wooden disk at the base of a short wooden rod that served as the core around which the b.a.l.l.s stood (fig. 41). The whole a.s.sembly was bagged in cloth and reinforced with a net of heavy cord.

In later years grape was made by bagging two or three tiers of b.a.l.l.s, each tier separated by an iron disk. Grape could disable men at almost 900 yards and was much used during the 1700's. Eventually, it was almost replaced by case shot, which was more effective at shorter ranges (400 to 700 yards). Incidentally, there were 2,000 sacks of grape at the Castillo in 1740, more than any other type projectile.

Spherical case shot (fig. 41) was an attempt to carry the effectiveness of grape and canister beyond its previous range, by means of a bursting sh.e.l.l. It was the forerunner of the shrapnel used so much in World War I and was invented by Lt. Henry Shrapnel, of the British Army, in 1784. There had been previous attempts to produce a projectile of this kind, such as the German Zimmerman's ”hail shot” of 1573--case shot with a bursting charge and a primitive time fuze--but Shrapnel's invention was the first air-bursting case shot which, in technical words, ”imparted directional velocity” to the bullets it contained. Shrapnel's new sh.e.l.l was first used against the French in 1808, but was not called by its inventor's name until 1852.

INCENDIARIES AND CHEMICAL PROJECTILES