The torpedo experiments against the Resistance, which have been suspended since November last, were resumed on June 9 at Portsmouth by the officers of the Vernon. The injuries received by the ironclad in the previous experiments having been repaired, so as to make the vessel watertight, the old ship was towed up the harbor, and moored in Fareham Creek. Our readers are aware that the Resistance is an obsolete ironclad which has finished her career as a battle ship, and that nothing could have converted her into a modern armorclad.
Although it was intended to render the experiments final and conclusive as a practical demonstration under service conditions of the destructive effects of the Whitehead torpedo when directed against a modern vessel of war, the results still leave behind them much uncertainty. The Resistance was built of iron, whereas battle ships are now exclusively constructed of steel, and it would be perhaps hazardous to state that the behavior of the two metals under a sudden and violent shock would be exactly the same. The construction of the double bottom of the old ship is also different. Since the last experiments were carried out against her, however, measures have been taken to make her as far as possible the counterpart, so far as under water arrangements and coal protection are concerned, of a modern ship of war.
At the last attack, the Whitehead was directed against the after part of the hull on the port side in wake of the boilers. During the present series of experiments the old ship was assailed on the same side, but directly amidships, in the neighborhood of the engine room. As no steam was got up in the boilers, the effect of the jar upon the steam pipes, glands, and feed connections remains a matter of speculation. So far as the consequences of the burst upon the structure of the hull itself is concerned, every care was taken to make the ordeal as complete and instructive as possible. The wing passage, which has a maximum diameter of 3 ft. diminishing to a point, was left empty, although at the former experiments the lower portions were filled with coal. But behind this, and at a distance of 8 ft. from the bulkhead, a longitudinal or fore and aft steel bulkhead 3/8 in. thick had been worked to a length of 61 ft., and, with the coal with which the intervening compartment was packed, formed (as in recent armorclads) a solid rampart, 20 ft. high, for the defense of the engine room.
The height of the double bottom between the outer and inner skin plating is 2½ ft. The watertight compartments were divided into stations by means of vertical lightening plates pierced by three holes, and in order to make them, as far as was practicable, resemble the bracket frames of a modern armorclad, the center of the plates was cut away so as to leave a single oval hole instead of the three circular holes. In view of the differences of opinion which exist on the part of experts on the subject of under water protection, the officers of the Vernon had determined to submit the problem to the test of experiment. For this purpose steel armor 1½ in. thick had been worked along the outside of the upper skin of the double bottom throughout one of the compartments, in addition to the other protection mentioned. The Resistance had been brought down by iron ballast to a trim of 25 feet 9 in. aft and 19 ft. 7 in. forward, giving a mean draught of 22 feet 8 inches. She was consequently rather further down by the stern than before, but was in other respects the same.
When in commission, the Resistance had a mean draught of 26 feet 10 inches. The present series of experiments was of even greater importance than the first series. The attack was gradually developed by means of fixed and outrigger charges of increasing power, and the coup de grace was not given by means of a service Whitehead in actual contact until various lessons had been derived.
The opening experiment on June 9 consisted of an attack directed against a new system of torpedo defenses which are to be carried by ships in action, or when in expectation of an attack, rather than an assault upon the ship herself. The previous experiments had clearly demonstrated that a Whitehead, when projected against a vessel at close range, and consequently with a maximum of motive force, could not get through the ordinary wire netting before expending its explosive energy in the air, and that the spars by which the nets are boomed out from the ship's side could be reduced to 25 ft. in length without danger to the hull. The ordinary wooden booms employed on board ship, however, are heavy and unwieldy, weighing, as they do, more than half a ton each. In ordinary circumstances, the spars cannot be lowered into place and the nets made taut in less than a couple of hours, and the work of stowing them is equally slow and laborious.
Mr. Bullivant, who manufactures the torpedo netting and hawsers for the navy, has devised a method of getting rid of the difficulties complained of by substituting steel booms for the wooden booms and an arrangement of pulleys and runners, whereby the protection can be run out and in, topped and brailed up out of the way, with great facility. The system was tried at Portsmouth last year with considerable success upon the Dido, but as it was thought that some of the fittings were somewhat frail and might collapse beneath the shock of a live torpedo, it was resolved to submit them to a practical test under service conditions upon the Resistance. The ship was consequently fitted with three of the steel booms on the port side. They were 32 ft. long and spaced 45 ft. apart, and connected by a jackstay to which the nets were attached. Each steel boom weighed 5 cwt., or less than half the weight of the ordinary boom, and whereas the latter is fixed to the ship's side by a hook which is liable to be disconnected or broken by the jerk of an exploding torpedo, Mr. Bullivant's boom works in a universal or socket joint, which cannot get out of gear except by fracture, and which permits the boom to be moved in any direction, whether vertically or fore and aft, close in against the sides.