Experiment.
Torpedo:—660 lbs. of gunpowder, enclosed in a buoyant cylindrical 1/4" steel case with domed ends, and contained in an inner 1/16" steel case. It was ignited by two Von Ebner fuzes placed in a charge of 1/4 lb. of gunpowder and enclosed in a glass bottle. It was placed 5' horizontally from the water line, 23·75' actual distance from target, and opposite No. 5 (middle) frame of target, 29' below the surface of the water.
Effect of explosion:—The ship was moored in 54' of water. She was lifted by the explosion, rolled over to port, and then settled to starboard, sundry large pieces of timber being thrown up in the air. The outer bottom of the target was broken through above the second longitudinal frame, from the fourth to the seventh frames laterally, and from the top of the target to the second longitudinal frame vertically, the hole made measuring about 9' high by 12' wide, or about 100 square feet in area. The inner bottom was also broken through between the top of the target and second longitudinal frame, and between the fourth and seventh vertical frames, the hole made being about 75 square feet in area. The bracket frames within the damaged area were but little damaged. The wing passage bulkhead was broken through opposite to Nos. 5 and 7 frames, the holes made being respectively 18 and 17 square feet in area. Through these holes the force of the explosion had made its way to the horizontal iron deck, forming the top of the target, which was completely broken through a little abaft No. 5 frame, the hole made measuring about 100 square feet in area. A piece of this iron deck, weighing, with the iron fastenings attached to it, about 1650 lbs., was thrown 16' against the upper deck beams. The target below the second longitudinal frame was comparatively but little injured. The outer bottom was indented and cracked in one or two places, but the inner bottom was uninjured. In addition to the damage to the target, the ship herself sustained serious injury, eleven of the lower deck beams, with their knees being broken (six being broken completely across). The main keel immediately under the target was also opened at the scarf, and the back of the ship was apparently broken. The hull had given out laterally to such an extent as to prevent the ship being taken into dock.
Experiments at Portsmouth, England, 1876.—The object of the following experiments was to determine the effect of comparatively small charges of gunpowder and gun-cotton exploded in actual contact with an ironclad, as would be the case in a torpedo attack either with locomotive towing or spar torpedoes.
Target:—the same as used in the experiments of 1874-5, which have been detailed at [page 229], &c., viz., the Oberon fitted to represent H.M.S. Hercules without the armour. Her mean draught was 11', and she was moored in 26-1/2' of water. The Oberon had been placed in a thorough state of repair.