An undated pic of the dynamite cruiser USS Vesuvius at anchor. Note the three 15" dynamite tubes projecting near the bow; they were aimed by pointing the ship at the target.

USN Photo

U.S. Naval Historical Center Photograph #NH 69211.

The USS Vesuvius taken sometime between 1890 and 1901.

Photo courtesy of the Library of Congress

Starboard broadside of the USS Vesuvius (Dynamite Cruiser) underway at an unknown location. Photo dates between 1890-1901.

Library of Congress, LC-D4-21047

The Dynamite Cruiser USS Vesuvius at New York, during the Columbian Naval Parade, 27 April 1893. Photographed by Loeffler (1864-1946).

Image courtesy of  DeGolyer Library, Southern Methodist University

Interior of the USS Vesuvius conning tower located behind the dynamite guns.

Photo courtesy of the Library of Congress

Bill Gonyo

Vesuvius carried three 15-inch (38-cm) cast iron pneumatic guns, mounted forward side-by-side at a fixed elevation of 16 degrees. Gun barrels were 55 feet (17 meters) long with the muzzles 15 feet (4.6 meters) above the deck 37 feet (11 meters) abaft the bow. In order to train these weapons, the ship had to be aimed, like a gun, at its target. Compressed air from a 1000 psi (70 atm) reservoir projected the shells from the "dynamite guns." Two air compressors were available to recharge the reservoir.

Photo courtesy of the Library of Congress

Interior image of the USS Vesuvius (Dynamite Cruiser) showing projectile carriers for the three guns. Photo dates from 1809-1901.

Library of Congress, LC-D4-20115

Interior image of the breeches of the dynamite guns of the USS Vesuvius (Dynamite Cruiser). Photo dates from 1890-1901.

Library of Congress, LC-D4-20113

USS Vesuvius air chambers for the dynamite guns. The shells fired from the guns were steel or brass casings 7 feet (2 meters) long with the explosive contained in the conical forward part of the casing and spiral vanes on the after part to rotate the projectile. The explosive used in the shells themselves was actually a "desensitized blasting gelatin" composed of nitrocellulose and nitroglycerine. It was less sensitive to shock than regular dynamite but still sensitive enough that compressed air, rather than powder, had to be utilized as the propellant. Shells containing 550 pounds (250 kg) of explosive had a maximum range of 1 mile (1.6 km), but range could be extended to 4000 yards (3.7 km) by reducing projectile weight to 200 pounds (100 kg). Maximum muzzle velocity was 800 feet (250 meters) per second. Range could be reduced by releasing less compressed air from the reservoir. Ten shells per gun were carried on board, and 15 shells were fired in 16 minutes 50 seconds during an 1889 test. The shells employed an electronic fuse which could be set to either explode on contact or delayed to explode underwater.

Photo courtesy of the Library of Congress

USS Vesuvius and USS Sterling laid up at Boston Naval Shipyard, circa 1900.

U.S. Naval Historical Center Photograph #NH 90373.