The late 19th century was a time of experimentation in the realm of naval and coastal defense weapons. The problems with black and brown powder – the corrosion and the massive amounts of smoke and soot they created - were well known.
Experiments with high compression powders indicated that much heavier and well-made gun tubes would be required and the steel industry struggled with the technology needed to create them. The inherent difficulties in these weapons systems caused some individuals to look for more innovative solutions.
One of the innovators was D. M. Mefford, an Ohio schoolteacher. Mefford invented a gun that lofted its shells through the use of compressed air instead of exploding powder. This type of gun became known by the unfortunate and inaccurate sobriquet of a “dynamite gun.”
What was the advantage of this system? There were many. First, since the weapon was not subjected to the tremendous force of exploding powder, the gun tube did not need to be fabricated from large amounts of steel. This was significant not only because advanced manufacturing processes would not be required, but because of the weight savings.
Weight was a major factor in warship design. A naval vessel was a designed series of trade-offs in the combination of speed, guns and armor. Any decrease in the weight of the guns meant a possible increase in speed or an increase in the amount of armor.
Second, since the projectile itself was not subject to the explosion in the gun tube, the armor on the projectile that was needed to allow it to survive the initial blast could be decreased. The weight saved in armor could be shifted to an increase in the shell’s explosive payload, allowing for a projectile with greater explosive capability.
Third, pneumatic guns were quiet. Even large, 15-inch pneumatic guns simply emitted the sound of a “loud cough” when fired.
Fourth, pneumatic guns fired without emitting a muzzle blast, which, combined with the quiet sound, allowed the guns to be well hidden at night.
Lastly, the guns also did not emit the large cloud of smoke, which often temporarily blinded gun crews and also gave away their position. All of these items combined to indicate a very promising future for pneumatic guns, but such was not the case.
Both the U.S. Army and Navy experimented with pneumatic guns. One of Mefford’s guns was mounted at New York’s Fort Hamilton. Here the gun sparked the interest of an army lieutenant in the 5th U.S. Artillery stationed at the fort, Edmund Zalinsky, a Polish immigrant who had served through the Civil War.
Zalinsky modified the gun’s design and, eventually leaving the army, became one of the heads of the Pneumatic Gun Company, which was created to produce and market the weapons.
Though a field gun, the Dudley-Sims dynamite gun was eventually produced independently; however, the true pneumatic guns were not really intended for field use. They were intended to be larger weapons, the type needed for use in coastal defense fortifications and as the main battery on naval vessels.
Batteries of 15-inch pneumatic guns were eventually mounted at fortifications in New York and at San Francisco’s Presidio. Pneumatic guns also served as the main batteries on the Vesuvius, the submarine Holland, and the American-made Brazilian warship Nictheroy.
Though the army had an ongoing interest in pneumatic guns, it was the navy that put the most effort into the development of the new weapon system. The navy’s efforts culminated in the commissioning of the Dynamite Gun Cruiser Vesuvius in 1890. Unfortunately, the design of the weapon system became “the tail wagging the dog” and the seaworthiness of the vessel became a distant second in the design requirements.
The Vesuvius represented the zenith of the effort to make pneumatic guns a standard naval weapon. The ship had three 15-inch pneumatic gun tubes, each 54 feet long, fitted in her bow. The tubes were constructed of thin, brittle cast iron since they were not subjected to the stresses of an explosion in the tube itself. The guns were immovable, however, fixed in position at an angle of 18 degrees to the main deck.
Unlike on most vessels, the guns were loaded deep in the bowels of the ship. To load one of the guns, the last several feet of the gun tube was pivoted down. Immediately forward of the pivoted breech of the tube was a very curious-looking object, basically a large, five-chambered revolver cylinder.
Each of the chambers held a projectile. To load the tube, one of the chambers in the revolver was lined up with the open breech, and a hydraulic ram pushed the projectile from the revolver into the tube. Once loaded, the tube was pivoted closed. The gun was now ready to fire.
The standard projectile was approximately seven feet long. The warhead was attached to a set of wood fins with a long shaft and could carry up to 250 pounds of high explosive. In flight, air passing over the tail fins caused the projectile to spin, making the projectile more accurate in the same way that rifling increases accuracy in a typical powder-fired gun. The muzzle velocity of the Vesuvius’s pneumatic guns was low, probably in the vicinity of 650 feet per second.
To fire the gun, air was injected into the tube. The compressed air, apparently 1,200 cubic feet of it supplied by two Norwalk compressors, was stored in reservoirs at a pressure of about 2,000 per square inch (psi). The air pressure used in the guns was actually about 750 psi, however. The range of the gun was altered, not by adjusting the gun elevation, but by altering the amount of compressed air released into the gun tube.
The guns were aimed and fired from the vessel’s cramped conning tower, a small station from which the vessel was steered as well as commanded in battle. Since the guns were fixed in position and facing forward, the only way to aim the guns was to aim the ship, steering toward the target.
Sighting was always a challenge, but was simplified when an actual sight was hung between two of the gun tubes. When the guns appeared to be on target, the man peering out of the ports in the conning tower pulled one of the three levers, one for each tube, releasing the compressed air into the gun tube, and lofting the projectile.
The projectiles fired from the pneumatic guns were the source of the unfortunate nickname of “dynamite guns.” The projectiles carried a payload of high explosive, which could be in the form of nitrocellulose, also known as “gun cotton,” nitro gelatin, or dynamite. Seldom was dynamite actually used, with the usual material being nitro gelatin.
It was the dynamite, however, that took hold of the public imagination and became so common that even the ship became officially the “Dynamite Gun Cruiser Vesuvius.” The nickname inspired fear, but not only to the enemy. Those who did not understand the vessel’s unique weaponry thought the ship unduly dangerous.
For instance, at the siege of the Cuban port of Santiago in 1898, the only time the large dynamite guns were used in action, the men of the U.S. North Atlantic squadron were very concerned that the small dynamite cruiser was in their midst. Fireman George Robinson of the Battleship Oregon commented “[Vesuvius] is some three miles away from us and we sincerely hope she will stay that distance away as she carries tons of high explosives and is quite dangerous, if the Spaniards ever hit her she might sink the entire [U.S.] fleet.”
Stored within Robinson’s own Oregon was more explosive material than what could be carried on Vesuvius.
At Santiago, the ship fired at the Spanish batteries night after night. One witness watched the Vesuvius’s attack and described the event. A “…brilliant flash illuminated the heavens and topped the distant mountains with fire. The earth trembled as though it were a live volcano…” The results of the firing appeared to be quite impressive.
The range of the Vesuvius’s guns was about one mile. Interestingly, tests showed the guns did not need to score a direct hit on a ship to sink it, as was generally required with a powder-based gun. It was found that the projectiles went horizontal when they hit the water and would travel 50 yards and still be lethal. This meant that it was possible to score a direct hit even if the projectile did not initially hit the target.
To ensure a hit, the three gun tubes would be fired at a target with one gun aiming 50 yards in front of the target, one gun on the target and one gun 50 yards beyond the target. This would allow for a much greater chance of a hit since effective area of a direct hit would be 150 yards deep rather than a few feet as with a powder gun.
Given the apparent success and advantages of the pneumatic “dynamite” guns, why did they fall out of favor? In fact, the weapon system fell out of favor before the system was even tested.
The Washington administration that had ordered Vesuvius was no longer in place when she came into being. The new administration looked toward more traditional systems. As a result, the Vesuvius never had adequate sea trials, and range tables for its guns were never developed.
Also working against her, Vesuvius suffered from problems that undermined the faith of the navy’s commanders. With the emphasis on the weapons, the design of the ship suffered. Vesuvius was a very small vessel, only 930 tons, 250 feet long and 26 feet on the beam, but she was built for high speed, attaining an amazing 21.5 knots.
She was long and narrow – too narrow. There was not adequate space to install her dual propellers without placing their shafts at an angle to each other. The result was that the propellers fought against each other so that the vessel could not use the propellers for slow speed maneuvering. The hull width also did not allow space for an adequately sized engine to turn the rudder at high speed. Therefore, at high speed, she had a turning radius greater than that of a battleship.
Her design caused her to roll horribly making some believe her to be unseaworthy. Her hull also was constructed allowing for a weak point where the superstructure began. She had a tendency to sheer rivets at this point, again giving the appearance that the vessel was unsafe.
Since the vessel appeared to behave erratically at sea, was unable to stay in formation, unable to maneuver in tight quarters, and was tossed like a cork in heavy seas, she did not inspire trust. With all of the inadequacies in the design of the gun platform – the ship – many believed that the weapon system could not be trusted either and never gave it a chance.
Vesuvius’s most obvious flaw was that the large guns all aimed forward and to aim the guns the ship itself had to be aimed. To fire her guns, she had to always be on the attack.
The projectiles, though they did not need to be heavily armored to survive being fired, did not carry adequate armor to allow them to penetrate a target. The shells generally exploded on the surface of a target, amid a dramatic show of fire, smoke and dust, but with little damage. The combination of slow airspeed and long projectile would have allowed it to be blown off target by heavy winds.
The least obvious flaw was one that did not have the chance to become apparent, but was one that would have doomed her. In the same way in which technology was initially having difficulty producing the steel needed for the powder guns, technology had not yet developed a valve that could properly and consistently control the amount of compressed air being released into the gun tubes. The result was that the guns could never attain consistent accuracy.
The advances in standard powder gun technology made continued effort in the development of the radical pneumatic gun system pointless. Both the army and navy soon lost interest. The pneumatic guns were removed from Vesuvius, Holland, and even Nictheroy, which the navy eventually bought back from Brazil.
By 1901, the army decided to remove the pneumatic guns from its forts, and the system, never fully tried, became but a footnote in the history of modern armament.
Editor’s Note: See Vol. 24, Nos. 3 and 4, the summer 2003 Roar column and fall 2003 Letters column, for more on pneumatic guns.
About the Author: Patrick McSherry is editor of the Spanish-American War Centennial at Web site (www.spanamwar.com), a member of the living history crew of the USFS Olympia and Independent Battery I, Pennsylvania Light Artillery, as well as a historical freelance writer. His most recent Artilleryman articles were about Fort Anne, Nova Scotia, and the U.S. Army Ordnance Museum.