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15-inch Pneumatic Dynamite Gun
A drawing of the 15-inch Pneumatic Dynamite Gun at Fort Winfield Scott from the Scientific American, Vol. 63, Issue 12.
Type	Dynamite gun
Place of origin	United States
Service history
In service	1890s–1904
Used by	United States Department of War
Wars	Spanish–American War
Production history
Designer	Edmund Zalinski
Manufacturer	Pneumatic Torpedo and Construction Company
Unit cost	US$60,000
Produced	1889–1901 (1889–1901)
No. built	11–15
Variants	2x 8.4 in (21 cm) caliber 2x 8 in (20 cm) caliber
Specifications
Length	50 ft (15 m)
Caliber	15 in (38 cm)
Warhead	Nitrocellulose and nitroglycerine
Warhead weight	50 to 200 lb (23 to 91 kg)
Detonation mechanism	Pressure
Engine	Steam generator
Operational range	6,000 yd (5,500 m)
Accuracy	~75 percent

The Zalinski dynamite gun referred to a series of dynamite guns which were designed and built by American military engineer and inventor Edmund Zalinski. Only approximately 15 of these guns were built, 11 of which were known as the 15-inch Pneumatic Dynamite Guns. They were 15 in (38 cm) in diameter and were installed on a series of experimental coastal artillery batteries initiated by the Endicott Board from 1894 to 1901.

The dynamite guns were commissioned by the United States Department of War for the defense of the US's Atlantic and Pacific coasts. They were designed to throw explosive projectiles from 2,000 to 6,000 yd (1,800 to 5,500 m) depending on their weight. The projectiles, colloquially known as "aerial torpedoes," could have contained anywhere from 50 to 200 lb (23 to 91 kg) of "desensitized blasting gelatin" composed of nitrocellulose and nitroglycerine. The guns themselves weighed over 200 tons, requiring the existence of a steam generator, air compressor, and other equipment to operate the guns.

After the guns were declared obsolete in 1904 due to significant technological advances in conventional artillery, the four batteries on which they were installed were decommissioned and the guns were scrapped for metal. Only two of the guns' original locations remain to this day; one abandoned battery is located at Fort Winfield Scott, in San Francisco, California, while the remains of another are located on the premises of a private resort on Hilton Head Island, South Carolina.

Design

Edmund Zalinski, pictured in the late 1800s.

The original invention of a gun that can fire an explosive charge with compressed air was developed by D.M. Medford of Chicago, Illinois, whose prototype was demonstrated in 1883 at Fort Hamilton, New York City. American artillery officer Edmund Zalinski saw the demonstration and began to improve the design, developing a series of his own prototypes over the next few years. Zalinski, a Polish-American immigrant who fought in the Civil War as an artillery officer, developed the gun with the purpose of penetrating the metal hull of enemy ships.

The dynamite gun featured a stand-alone steam generator that powered its electrical plant, which gave the gun its ability to pivot and rotate. The gun was developed to eliminate gun smoke, since compressed air was supplied by a steam-driven compressor at 2,500 psi (17 MPa) to propel a dynamite-filled projectile out of its barrel. Owing to the gun's design, the projectiles did not explode before they reached their target, since no heat was given off by the propulsion, which was operated at relatively low pressures.

Diagram of an original Zalinski dynamite gun

There are three separate fuses to these dynamite shells: one in the head, which acts on immersion; one in the base, which acts when a solid substance is hit; and the third explodes the shell after sinking to the bottom, in case the immersion fuse should happen to fail. Dynamite shells could not be used in normal guns because the impact of the propellent firing would trigger the dynamite and the shells would explode while still in the gun tube. Compressed air drove the shells out of the gun tube at a lower velocity and with less impact.

Because of the lower pressure and no explosive propellant the gun tubes were very thin and actually required a cantilevered support to keep the gun tube rigid. Since the gun was experimental, the contractor provided the guns, carriages and the emplacements as well as the considerable amount of machinery necessary to produce the highly compressed air. The shells were fused electrically and could be set to explode with a delay.

The projectiles came in the full 15-inch and three sub-caliber, 15-inch projectile, eleven feet long, weight when fully charges-1,150 lbs -- 10-inch sub-caliber projectile eight feet long, weight when fully charged 570 lbs. --- 8-inch sub-caliber projectile seven feet long, weight when fully charged -- 370 lbs -- 6-inch sub-caliber projectile seven and one half feet long, weight when fully charged -- 300 lbs. The fuse on the projectile was mechanical in nature and could be set to act on impact or delayed.

Testing

Zalinski demonstrated this 8-inch prototype to a large number of visitors, which could fire a projectile with a 100 pound dynamite charge over two miles. The projector was at least as accurate as conventional cannon of the same calibre. By 1886 he had interested a number of naval officers in the possibilities of the weapon. The Department of the Navy decided to fund the construction of a "dynamite cruiser", and investors set up the Pneumatic Dynamite Gun Company in New York to manufacture guns to Zalinski's design. In 1887, the navy arranged a test in which the dynamite gun fired a shell that completely destroyed a target ship—the USS Benjamin Silliman.

The publicity this got led to the decision to build the USS Vesuvius "dynamite cruiser" armed with three such weapons. Zalinski, by now US Naval attaché to Russia, returned to supervise development of these projectors as well as the construction of similar ones for mounting in coastal -defence fortifications. Over the objection of the army, Congress appropriated $400,000 for the purchase of "pneumatic dynamite guns" in 1888 as part of the coastal defense modernization program. In the Spring of 1889 the ordnance department issued an order for the purchase of three of these weapons (all 15-inch caliber) for the San Francisco Defense area, for the cost of $187,500.00 (the original appropriation was $400,000.00, the money that was not used for the new guns, went to help modernized some of the Endicott batteries.

Zalinski guns at Battery Dynamite, Fort Winfield Scott, San Francisco.

Five such systems were under consideration, although the Board of Ordnance and Fortification contracted with the Pneumatic Torpedo and Construction Company as the final tender. Dated 27 January 1893, the Pneumatic Torpedo and Construction Company was slated to erect three of these dynamite guns at Fort Winfield Scott.

After a careful study of the results obtained by the Pneumatic Torpedo and Construction Company, the board finds that their system is the only one that has fully demonstrated an ability to safely and accurately project nitro-gelatin, or high explosives of equal power and sensitiveness, in large masses.

— Board of Ordnance and Fortification

Actual penetration of a trial shot from a 16%-inch, no-ton gun. The missile passed through 20 inches compound plate, 8 inches wrought iron, 20 feet oak timbers, 5 feet granite, 11 feet concrete, and buried itself 6 feet in a brick wall.

The batteries of 15-inch guns of this system that have been erected at Fort Hancock, New York Harbor, and Fort Scott, San Francisco Harbor, have shown that these guns are capable of throwing 100 pounds of nitro-gelatin to a distance of 4,800 yards, 200 pounds, 3,500 yards, and 500 pounds, 2,600 yards, with great accuracy. The composition of which was: Nitroglycerine, eighty-seven per cent; guncotton, seven per cent; camphor, four per cent; carbonate of magnesia, two per cent.

As was reported in the Scientific American Supplement dated 9 July 1898, during the dynamite gun's testing at Fort Winfield Scott, 34 percent of the hits were required to fall within a rectangular area 5,000 yards (4,600 m) away, measuring 300 ft (91 m) by 90 ft (27 m). The actual test went better than expected, with 75 percent of the shots landing within the required area; a rectangle just 70 ft (21 m) wider would have had a 100 percent accuracy rate.

Locations

It was recommended that "arial torpedoes" would be installed all throughout the coast where the channels are narrow and too deep to be defended by subaquatic torpedoes. Approximately 15 of the Zalinski dynamite guns were ever built. Eight of them were barbette-mounted, located in batteries on both the Pacific and Atlantic coasts of the United States, while five more were mounted on ships. The installations where the guns were housed were called Dynamite Batteries, unofficially named for the type of gun it held.

Dynamite gun muzzles on USS Vesuvius.

The number of guns to be mounted on the Atlantic Coast was reduced from seven to three. This reduction comprised four 15-inch guns, which were to have been mounted in the batteries of two guns each, at Fort Schuyler, New York, and Boston, Massachusetts.

Mounted at	Quantity	Caliber	Installed	Removed	Location	Refs.
Fort Winfield Scott	3x	15-inch	1895	1904	San Francisco, California
Fort Hancock	2x, 1x	15-inch, 8-inch			Sandy Hook, New Jersey
Fort H. G. Wright	1x	15-inch			Fishers Island, New York
Hilton Head Military Reservation	1x	15-inch	1897	1902	Hilton Head Island, South Carolina

Three 15 inch caliber dynamite guns were mounted on board the USS Vesuvius in 1888, only to be removed by 1904. The USS Buffalo also had one 15 inch gun installed. In addition to the original 8-inch prototype, the "Zalinski boat" was fitted with an 8-inch gun, and USS Holland (SS-1), the first commissioned US submarine was fitted two 8.4-inch (210 mm) Zalinski dynamite guns.

Hilton Head

The 15-inch Pneumatic Dynamite Gun Plant was built from 1897–1901 to facilitate the defense of Port Royal Sound during the Spanish–American War.

It is located on the site of the Hilton Head Military Reservation, which was built atop the site of former Fort Walker/Welles. Fort Walker/Welles was established as a Confederate military installation during the Civil War, commissioned by General P. G. T. Beauregard to guard the entrance to Port Royal Sound.

Today, the second Battery Dynamite is located within the boundaries of the Port Royal Plantation, a private residential community with restricted public access. The only remains are its foundation, gun mount and barrel, which are in a partially destroyed condition.

It was first tested at Coggins Point on 6 January 1902. During one its test firings, the dynamite gun set off a large forest fire on a nearby island. The Hilton Head gun was fired more than 100 times in late 1901 and early 1902 without any incident. It was dissembled in 1902. In a memo by Sargent Major Ira MacNutt to the Chief of Ordnance, it was reported that the 75 percent of the dynamite gun's shots fell within the required area, which was greater than requirements set down by the Ordnance Department itself. The longest range of this particular gun's projectile was reported to have been 5,732 yards (3.257 miles).

On April 26, 1902, that department turned over the gun and the plant to the artillery which sent a detachment from nearby Fort Fremont to guard and service the weapon.

Obsolete

At this same time, the Board of Ordinance and Fortification declared dynamite gun batteries obsolete due to the advances in conventional artillery. By the 1900s, smokeless gunpowder howitzers and coastal artillery pieces could fire much larger shells more accurately at distances several times further and the short, short, career of the dynamite gun was over. As a result the War Department abandoned the plant and disposed of the gun sometime after June 1902. All four batteries were sold for scrap, in 1904, and the builders went out of business.

What finally made the dynamite gun obsolete was the development of new high explosives, such as ammonium picrate, in the late 1890's. These new explosives could be fired from conventional cannon, and in combination with armor-piercing shells were an effective weapon versus armored warships. A dynamite gun was as expensive to construct as a 10 or 12-inch shore defense battery, but had a shorter range and was more expensive and complex to maintain. Moreover, the increasing range of ship-mounted weapons meant that an invading navy's guns would out range the dynamite gun and so could destroy it from a distance with impunity. As a result, dynamite guns were no longer useful and so were scrapped.

See also

• Steam cannon

References

Footnotes

Further reading

• Berhow, Mark A. (2004). American Seacoast Defenses: A Reference Guide (2 ed.). Coast Defense Study Group Press. ISBN 0974816701.

External links

• Hogan, Don. "South Carolina Markers". Georgia Civil War Markers. Retrieved January 26, 2020.