|Spherical Case (The Shrapnel Shell)
|One type of ammunition for smooth bore cannon which was of significant
value is Spherical Case ("Shrapnel"), developed by General Henry Shrapnel (1761-1842) of the British Army.
It was in common use by the the early 1800's.
It consisted of a thin walled shell loaded with iron or lead balls, a small bursting charge and a time fuze. The shell was intended to explode in flight, just prior to reaching the target. The bursting charge was designed to be just strong enough to rupture the case and release the balls, which continued along the original path of the projectile, creating the effect of close range canister. It proved an effective weapon and was significant to the continued dominance of smooth bore artillery on the battlefield after the appearance of the rifled musket.
At left is a sectioned 12lb Spherical Case (Federal, circa 1864). It is 4.5 inches in diameter with a Bormann time fuze. The shell is manufactured by placing lead balls into the hollow shell, then filling it with molten sulfur which cools and forms a solid matrix. A central cavity is drilled out, then filled with black powder. Finally the fuze is screwed in, completing the round.
Maximum range was about 1,200 yards.
|Bormann Time Fuze
Invented about 1840 by Belgian Army Captain Charles G. Bormann, this time fuze used
a train of compressed black powder shaped in a horizontal crescent ending at a central booster charge.
The housing is a pressed disc made of tin/lead, calibrated from 1/2 to 5-1/4 seconds. When complete it was a hermetically sealed unit.
A punch was used to open the top disc at the time setting desired. This exposed the powder underneath.
fired, flame ignited the fuze train at that opening which started burning
in both directions at the same rate. The path towards the booster is the
important one. In the photo the fuze has been "cut" at the 2 second mark.
(Actually closer to 1-1/2 seconds). The illustration at right shows the internal
The Bormann fuze was employed by the United Stated Ordnance Department as early as 1852. It had a reputation for reliability and consistency among the Federal Forces, but the Confederate copies had manufacturing quality problems and were not nearly as reliable. The 12-pounder projectile was the most common Federal shell employing the Bormann time fuze.
|Here is a 12-pound case with an attached sabot. The
sabot is a wooden cup designed to align the ball, keeping the fuze forward
and centered in the cannon bore. If the fuze was not aligned that way,
the blast from the firing gun could penetrate the thin fuze cover and cause a premature detonation.
Iron bands with a disc on top held the ball. The fuze was exposed through a hole in the disc. The loose fit in the gun barrel ("windage") allowed flame to envelope the projectile when fired which was more than sufficient to ignite the fuze.
A deep groove cut into the base of the sabot allowed a cartridge bag to be attached, creating what was known as a "fixed round". Fixed ammunition made for much quicker loading.