Effect of explosion:—Bow observed to be lifted several feet. Several angle irons and bracket frames were cracked, and numerous rivets in outer bottom were broken off. The outer bottom on the starboard side was indented between the frames, and brackets were disturbed over a space of 100 feet; inner bottom uninjured.

6th Experiment.

Torpedo:—As in previous experiment. It was placed on the ground, 28·5' horizontal, opposite No. 36 frame on the starboard side, and 30 feet from the stern; 49·5' below the surface of the water.

Effect of explosion:—Several plates in the outer bottom were cracked, and outer bottom made to leak in several places, owing to the fractures in the plates, rivets being started, and seams being opened. Considerably more damage was effected than in previous experiment, but inner bottom still remained uninjured.

7th Experiment.

Torpedo:—As in the 5th experiment. It was placed on the ground, immediately under the edge of the outer bottom, 39-3/4' from the target, and opposite No. 18 frame, 70' from the stern; 50' below the surface of the water.

Effect of explosion:—Outer and inner bottom broken entirely asunder at No. 19 frame on the starboard side, and between Nos. 16 and 17 on the portside. A fracture was caused in the outer bottom extending from the shelf plate to upper edge of strake next the keel on the starboard side, and from the shelf plate to upper edge of flat keel plate on the port side. A fracture was also caused in the inner skin extending from the topside to the outer edge of the garboard strake on the starboard side, and from the topside to upper edge of garboard strake on the port side; this including a fracture of the keel at No. 17. The vertical keel, the longitudinals, as well as numerous bracket plates and angle irons, were broken, and about 2000 rivets in the outer bottom were rendered defective.

The outer bottom was indented over a considerable length, the indentation being greatest between the frames, and the maximum being 8 inches. The inner bottom was not indented or damaged, with the exception of the fractures before mentioned.

Experiments at Pola, Austria, 1875.—These experiments were carried out to determine the effect of very heavy charges of dynamite on an iron pontoon fitted with a double bottom, similar to that of H.M.S. Hercules.