3rd Experiment.
Torpedo:—112 lbs. of gunpowder, rifle small grain, enclosed in cylindrical steel case placed inside an iron case, with an air space all round; steel case, 9-1/2" × 22-1/2" × 1/32"; iron case 33" × 25" × 1/4". It was placed 12' from No. 5 frame, 9·25' below the surface.
Effect of explosion:—Centre of ship lifted bodily, as if her back was broken; ship then rolled heavily to port. On board fire engines and troughs displaced several feet: shores and struts started, showing that the shock was considerable. The outer bottom on each side of the centre dividing plate indented to a depth of 1 to 1-1/2 inches; numerous rivets started, and some sheared. The leak was considerable, owing to the number of rivets that were started. The strength of the plates was not considered to be materially affected by the indentations; the rivets, 239 in number, were replaced; and the target prepared for the next experiment.
4th Experiment.
Torpedo:—33 lbs. of dynamite, enclosed as in first experiment. It was placed 15' from No. 7 frame, 9·25' below the surface of the water.
Effect of explosion:—Ship rolled slightly to port. A bolt securing the midship transverse bulkhead to beam was sheared. No damage done to the target.
5th Experiment.
Torpedo:—66 lbs. of dynamite, enclosed in steel cylindrical case, no air space, 13·5" × 13" × 1/32". It was placed 21' from No. 3 frame, 9·25' below the surface of the water.
Effect of explosion:—A rivet in outer bottom, above water line at fore end of target, was sheared. A few rivets in outer bottom opposite charge, and two in after compartment, were started, but no leak was perceptible. Several shores slightly displaced.