Experiment at Chatham, England, 1865.—This experiment was carried out to ascertain the effect of gunpowder torpedoes on the bottom of a wooden ship.

Target:—H.M.S. Terpsichore, a wooden sloop of war.

Torpedo:—150 lbs. of fine-grained powder. Two were used. They were placed on the ground, about 13' below the ship's keel, and 2' horizontally clear of her side.

Effect of explosion:—A hole of about 4' radius was made, about 19' nearly vertical from the charge; the Terpsichore sinking a few minutes after the explosion.

Experiment in Austria.—The object of this experiment was to ascertain the effect of a very large charge of gun-cotton exploded at some distance from the side of a wooden vessel.

Target:—A wooden sloop.

Torpedo:—400 lbs. of gun-cotton, placed 10' below the surface of the water, and 24' horizontally from the bottom of the vessel.

Effect of explosion:—Complete destruction of the vessel.

Experiments at Carlscrona, Sweden, 1868.—These experiments were made to investigate the effect of submarine contact mines, charged with dynamite, against a strong wooden vessel, as well as against a double-bottomed iron vessel. They were carried out under the supervision of Lieut.-Colonel Zethations, of the Royal Swedish Navy.

Target:—The hull of a 60 gun frigate, which had been built in 1844; it had been cut down to the battery deck, and the copper removed. Her timbers and planking were quite sound; timbers of oak about 13" square, and 1" apart; planking of Swedish pine, 5-1/2"; bottom strengthened inside with wrought-iron diagonal bands, 6" by 1-1/4"; inside planking running half way up to the battery deck of oak; 6" thick. This completes the wooden target.

On the port side a quadrangular opening was made, and fitted with a construction representing a strong double iron bottom, firmly fastened to an oaken frame that had been put on inside, on the four sides of the opening, and with through-going bolts, 1" in diameter, to the timbers.

Torpedoes:—No. 1.—13 lbs. dynamite, enclosed in 1/12" iron case. It was placed on the starboard side, amidships, 7' below the water line, and 2' 2" from the bottom of the ship.

No. 2.—16 lbs. dynamite, enclosed in a glass vessel. It was placed on the starboard side, 7-3/4' below the water line, 3' from the bottom of the ship, and 40' from her stern.

No. 3.—16 lbs. dynamite, enclosed in 1/12" iron case. It was placed on the port side, 5-3/4' below the water line, 2' from the bottom of the ship, and 30' from her stern.

No. 4.—10 lbs. dynamite, in a case as above. It was placed on the port side, 6-1/2' below the water line, 2-1/6' from the bottom of the ship, and 70' from her stern.

No. 5.—13 lbs. dynamite, in case as above. It was placed 7-1/3' below the water line, 2-1/6' from the centre of the iron bottom.

These five torpedoes were fired at the same moment.

Effect of explosion:—The hull of the ship was lifted about a foot, and sunk in 1-1/2 minutes.

No. 1 Mine.—Timbers broken and thrown inside, into the hold, on a space of about 15' × 8'; three more timbers on one side of this hole broken; inside oak planking rent off on a length of 14'; two iron bands torn up and bent, one of them broken in two places; outside planking torn off on a space of 21' × 12'; several planks still higher up broken.

No. 2 Mine.—Timbers blown away on a space of about 8' square; inside planking torn off on a length of 20'; two iron bands broken, and torn up and bent; and outside planking rent off on a space of 19' × 12'.

No. 3 Mine.—Timbers blown away on a space of 10-1/2' × 12' at one end, and 6' at the other; inside planking off for a length of 14'; one iron band torn up, and one broken; outside planking off on a space of 18' × 25' × 15'.

No. 4 Mine.—Timbers blown away on a space 4' × 16'; on the sides of this hole, ten timbers were broken; two iron bands torn up, and one broken; inside planking off for a length of 20'; outside planking off for a space of 20' × 23' × 10', and 13 feet.

No. 5 Mine.—The gas sphere of this mine had hit the middle of the outside plates on one of the angle-iron ribs. This rib was torn from the timbers and bent up, nearly 2' in the middle, but not broken. There was an oval hole in the outside plates 4' × 3' between two ribs, which ribs, with the plates on edge riveted to them, were bulged out about 5 inches. The inner plate, one large piece was blown up in a vertical position, after having cut all the bolts and rivets, sixty of 1", and thirty of 3/4", save those that fastened the lower side to the oaken frame and timbers. On a length of 30' and height of 20', the bottom, on all sides of the iron construction, had been bent inwards; the greatest bend was about 5"; three deck beams above had been broken.

By the joint effect of all the mines, almost all the iron deck beam knees had been rent from the side, and there was an opening between deck and hull on both sides for a length of about 130 feet.

Experiment at Kiel.—Target:—A large gun-boat, greatly strengthened internally by solid balks of timber.

Torpedo:—200 lbs. gunpowder. It was placed nearly under her keel, at a distance of 15 feet.

Effect of explosion:—Complete destruction of the vessel.

Experiment in England, 1874.—Target:—A rectangular iron case 20' long, 10' high, and 8' wide, divided into six compartments by means of one longitudinal bulkhead midway between the front and rear faces of the target, and two athwartship bulkheads equidistant from the ends of the target. Thickness of front and rear faces 11/16", of longitudinal bulkhead 1/4", of athwartship bulkheads 3/8".

Torpedo:—100 lbs. of gunpowder, enclosed in a spar torpedo case and fired by two detonators. It was exploded in contact with the target, 7-1/2' below the surface of the water, and 7' from top of target.

Effect of explosion on the target:—"Front of centre compartment destroyed and top blown off. Plate representing inner skin destroyed. Back of centre compartment (rear face of the target) much bulged, and penetrated; the hole measured 36' × 15". Large portions of the target were thrown to a height of 150 to 200 feet, and from 80 to 100 yards' distance."

The effect of explosion on a ship's pinnace, which had been placed 16 feet from and at right angles to the front face of the target, with steam up, and canopy and shield in position, was that a large quantity of water was thrown back in the boat, putting the fires out, and filling the boat up to her thwarts, but otherwise the boat was uninjured.

Experiments at Copenhagen, Denmark, in 1874.—The object of these experiments was to ascertain if a ship's armoured side would be seriously injured by a torpedo exploded in contact with it.

1st Experiment.

Target:—1" thick, and 2' × 2', supported in a horizontal position on a substructure consisting of 8" timber resting on two pieces of 6" timber under two sides, and completely supported by earth up to lower edge of substructure.

Torpedo:—33 lbs. of dynamite, enclosed in a square wooden case 2-1/4" high, and 5·5" × 5·5"; it was placed on the middle of the earth with 8" of earth tamping; this tamping representing the resistance of a thin stratum of water.

Effect of explosion:—The plate was broken into four pieces, and substructure crushed.

2nd Experiment.

Target:—2" thick, and 2' × 2-1/2', supported in a horizontal position on a substructure as above, but resting on four piles of 6" x 6" timber.

Torpedo:—8·9 lbs. of dynamite, enclosed in a wooden case 4" high, and 5" × 10". It was laid with one edge on the plate, the other edge 3" above the plate; same tamping as above.

Effect of explosion:—The plate broken into three pieces, and substructure crushed.

3rd Experiment.

Target:—5" thick, and 3' 8" × 4' 7", supported in a horizontal position on a substructure as above, but eight piles of 6" × 6" timber used. Plate bolted to the structure with eights.

Torpedo:—44·4 lbs. of dynamite, enclosed in a wooden case, of same thickness as the Harvey torpedo, and 4" × 13" × 21"; it was placed with surface against the plate, one edge 2" and the other 5-1/2" from the plate; tamping as before.

Effect of explosion:—Plate bulged 3-1/4" in the middle; substructure completely crushed.

4th Experiment.

Target:—5" thick, and 3' 8" × 4' 7"; this was the same plate as used in the previous experiment, laid with bulge uppermost on two beams under the short sides.

Torpedo:—44·4 lbs. of dynamite, enclosed in a cylindrical tin box 7-1/2" × 2'; it was placed on top of plate 11" from one side and with ends 9-1/2" from edge of plate; tamping as before.

Effect of explosion:—A corner of the plate broken off.

5th Experiment.

Target:—Same plate placed vertically in the earth.

Torpedo:—44·4 lbs. of dynamite, enclosed in a cylindrical tin box 8·5" × 18"; it was placed on timber, so as to rest against the face and centre of the plate; tamping as usual.

Effect of explosion:—Plate broken into four pieces, two of which were large; pieces hurled over parapet, one fell at a distance of 400 feet.

Experiments at Carlscrona, Sweden, in 1874-75.—These experiments were carried out by the Swedish torpedo authorities, to ascertain the effect of different sized charges of dynamite and gunpowder, enclosed in divers cases, and exploded at various distances from a target which represented in all respects, with the exception of the armour, a section of the side of H.M.S. Hercules before the boiler room, she being at that time one of the most powerful vessels afloat.

Target:—32' in length, and fitted into the side of an old line of battle ship. Similar in shape to a wing tank, and comprised a double bottom in four water-tight compartments, a wing passage in two water-tight compartments, and two large water-tight compartments in rear of all. It extended from 2' above the water line to within about 5' of the vessel's keel. The thickness of the plates forming the target were:—outer bottom, lower portion 13/16"; part where torpedo took effect, 3/4". Inner bottom, and wing passage bulkhead, 1/2". Vertical and longitudinal frames, both solid and bracket, 7/16". The longitudinal frames were bracket frames, with the exception of the second, which was solid and water-tight, with its outer edge about 8' below the water line. The vertical frames, of which there were seven, were placed 4' apart, the central one being solid and water-tight, the others being bracket frames. The ship was moored in 42 feet of water; the charges were detonated, one fuze being used in all but No. 3 experiment, when five fuzes were employed.

1st Experiment.

Torpedo:—33 lbs. of dynamite, enclosed in cylindrical steel case, no air space; height 10·75", diameter 10·75", and thickness 1/32". It was placed 25·5' from the target, opposite No. 7 frame, and 9·25' below the surface of the water.

Effect of explosion:—Ship appeared to be lifted bodily. A rivet in the midship longitudinal bulkhead of fore compartment was loosened. The torpedo was fired from the ship, and the shock felt was not very great.

2nd Experiment.

Torpedo:—47·2 lbs. of dynamite, in cylindrical steel case, no air space; height 12", diameter 12", and thickness 1/32". It was placed 25·5' from No. 5 frame, 9·25' below the surface of the water.

Effect of explosion:—Ship appeared to be lifted bodily. A leak was started in the outer bottom opposite to charge, caused by the loosening of five rivets.

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.

6th Experiment.

Torpedo:—33 lbs. of dynamite, enclosed as in first experiment. It was placed 12·75' from No. 7 frame, 9·25' below the surface of the water.

Effect of explosion:—Ship not lifted as much as was the case in No. 3 experiment; but explosion much sharper. On board, fire engines were capsized, and vertical shores displaced. Outer bottom opposite charge indented to a depth of about 1/2 an inch, other parts less bulged, and many rivets started.

7th Experiment.

Torpedo:—33 lbs. of dynamite, enclosed as in first experiment. It was placed 4' from No. 4 frame, 9·25' below the surface of the water.

Effect of explosion:—Effect very great; ship hurled suddenly to starboard. On going on board two minutes after the explosion, the fore compartment was found full, the after compartment became full ten minutes later. Shores and struts were considerably displaced, and there was evidence that the ship had sustained a severe shock. Outer bottom injured over an area 14' × 16', the plates being split in all directions; one piece, 5' square, was torn completely off, and an irregular hole was formed in the outer skin 14' × 12'. In the inner bottom below the wing passage bulkhead a piece 6' × 9' was blown completely out; the wing passage bulkhead was torn from the longitudinal frame and split from top to bottom. The inner skin above the upper longitudinal frame was torn from the latter, and forced in and upwards, but was not otherwise damaged. The vertical bracket frames Nos. 3 and 4, the latter opposite the torpedo, were destroyed, but the solid frame No. 5 was almost uninjured. The outer bottom, where it was not torn off, was forced in 7', or 4' beyond where the inner bottom had been.

8th Experiment.

Torpedo:—660 lbs. of gunpowder, enclosed in a buoyant cylindrical 1/4" iron case. It was placed 32·3' from No. 4 frame, 29·25" below the surface of the water.

Effect of explosion:—The ship and target had been thoroughly repaired, and were in good condition when this experiment was made; the ship was in this case moored in 65 feet of water. No effect was produced on the target by the explosion.

9th Experiment.

Torpedo:—19 lbs. of dynamite, enclosed in a cylindrical steel case with arched ends. It was placed 10·5' from No. 3 frame, 9·25' below the surface of the water.

Effect of explosion:—Effect produced apparently equal to that by No. 3 charge of 112 lbs. of gunpowder at 12'; indentation being from 1/2 to 1-1/4 inches in the outer skin opposite the torpedo.

10th Experiment.

Torpedo:—19 lbs. of dynamite, enclosed in a case similar to that used in the 9th experiment. It was placed 3·3' from No. 7 frame, 9·25' below the surface of the water.

Effect of explosion:—Hole produced in outer skin, 6·5' × 2' to 5'; inner skin only bulged and slightly cracked in two places. Above the longitudinal frame, a bulge was made in the outer skin 8' × 7', with the above-mentioned hole; below the longitudinal frame the indentation was 14' × 5' and 2·1" deep, with two horizontal cracks 10' x 13', and several inches broad.

11th Experiment.

Torpedo:—112 lbs. of gunpowder, enclosed in a cylindrical case of 3/64" steel, placed in a 3/16" steel case, with 223 lbs. of buoyancy. Ignition effected by a glass igniting bottle. It was placed 5·75' from No. 5 frame, 9·25' below the surface of the water.

Effect of explosion:—There was but little upcast of water outside the ship, but a great upcast through the ship. She immediately lurched to starboard, and on boarding her five minutes after, the target was found full of water.

The effect on the target was as follows, above the 2nd longitudinal frame, where strengthened by the wing passage bulkhead:—Outer bottom blown away from the 4th to the 6th frames for a length of 8 feet and a height of 4-1/2 feet, and bent in 6-1/2 feet. Inner bottom bent in and broken through between the 4th and 5th frames, with an irregular hole 8' square, and between the 5th and 6th frames, a similar sized hole. Wing passage bulkhead was bent in 2" to 3", and riven for a length of 29'; in the water-tight middle bulkhead athwartships the rivets in two vertical joints were completely torn away.

Between the 2nd and 3rd longitudinal frames, and below the wing passage bulkhead, both the inner and outer bottoms were completely blown away for a length of 12 feet and a height of 4 feet. The vertical and horizontal frames between the two bottoms had kept their position unchanged, and excepting that the bracket plate by frame No. 6 was bent, cracked, and torn away, the damage they had sustained was limited to some comparatively slight bending. The open hole formed in the target measured 76 square feet in outer bottom, and 60 square feet in inner bottom.

Comparing the effect of this torpedo with the 7th, 33 lbs. of dynamite; with the latter charge the breach was made at the cost of the bottom plates as well as the vertical and longitudinal frames, which were completely torn asunder and strained; with the gunpowder charge, only the bottom plates were broken through, whilst the plates whose directions were nearly parallel to the lines of explosive effect were but little affected.

Experiments at Portsmouth, England, 1874-75.—The object of these experiments was to ascertain the effect of 500 lbs. gun-cotton torpedoes exploded at various distances from a target representing the double bottom of H.M.S. Hercules.

They were carried out in Stokes Bay, under the supervision of officers belonging to the torpedo department of the Royal Engineers, and a torpedo committee, composed of naval and military officers.

The Oberon, the vessel chosen for these experiments, was fitted with a double bottom, representing as nearly as possible that of the Hercules without the armour; also with a surface condenser, and its connections; a donkey Kingston feed-valve; and athwartship water-tight bulkheads, which divided the ship into seven water-tight compartments. The outer skin was composed of 3/16" and 7/8" iron plates. In her starboard side at different points were fixed forty-four crusher gauges, and over each side were suspended six shots, each fitted with a crusher gauge.

Displacement of the Oberon about 1100 tons.

The ship was anchored head and stern. Her mean draught of water during the experiments was 11 feet.

1st Experiment.

Torpedo:—500 lbs. of gun-cotton, in discs saturated with water, and enclosed in an iron cylindrical case, 34" × 30" × 1/4", with arched ends; the primer consisted of two dry discs, and two detonators. It was placed 101' horizontal from the target, and opposite the condenser on the starboard side; 47' below the surface of the water, on the ground.

Effect of explosion:—No damage was done to the hull, or condenser, but light articles, such as bunker plates, gratings, tank lids, &c., were displaced.

2nd Experiment.

Torpedo:—As in first experiment. It was placed on the ground, 80' horizontal and opposite the condenser on the starboard side, 48' below the surface of the water.

Effect of explosion:—No damage was done to the hull, of condenser, but the bunker plates, gratings, &c., were displaced to a greater extent than in the previous experiment.

3rd Experiment.

Torpedo:—As before. It was placed on the ground, 60' horizontal, and opposite the condenser on the starboard side; 47' below the surface of the water.

Effect of explosion:—No damage was done to the hull. Flanges of the condenser inlet pipe were cracked, and several of the joint bolts were broken. The condenser had been thrown up bodily, and had torn away its holding down bolts; but it was not as well secured as it would have been had it formed part of the machinery of a ship.

4th Experiment.

Torpedo:—As before. It was placed on the ground, 50' horizontal, and opposite the condenser on the starboard side; 48' below the surface of the water.

Effect of explosion:—Outer bottom on starboard indented over a length of about 100', being forced in between the frames; maximum indentation, 3/4". Many bracket frames were disturbed, and outer angle iron of water-tight longitudinal was started for a length of 30', and made to leak slightly. The shell of the condenser was cracked in two places, 3' and 5' in length. Bolts securing condenser, and flanges of pipes and valves, were all more or less damaged. Condenser was rendered unserviceable.

5th Experiment.

Torpedo:—Same charge as before, but the primer consisted of four dry discs, and two detonators. It was placed 28·5' horizontal, opposite No. 9 frame, on the starboard side, 36' from the stern; 48' below the surface of the water, and 22' from the ground.

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.

Target:—An iron pontoon 60' long and 40' beam, with circular ends and fitted with a double bottom, also a condenser and two Kingston valves.

1st Experiment.

Torpedo:—617 lbs. of dynamite. It was 62' horizontally from the keel, 53' actual distance from the side, and opposite amidships, 40·5' below the surface of the water, and 20' from the ground.

Pontoon:—Draught of water 19', and moored in 62' of water.

Effect of explosion:—The pontoon moved away bodily a distance of 13 feet; a few rivets in the outer bottom were started, and the outer skin was slightly indented between the frames; the maximum indentation being 1·5". No other damage was sustained by the hull. Several of the screws securing the flanges of the Kingston valves were slightly loosened.

2nd Experiment.

Torpedo:—585 lbs. of dynamite. It was placed 60' horizontally from the keel, 48' actual distance from the side, and opposite amidships; 36' below the surface of the water, and 42' from the ground.

Pontoon:—Draught of water 19·5', and moored in 74' of water.

Effect of explosion:—The pontoon, which had been more rigidly moored than in the previous experiment, was moved bodily away a distance of 4 feet. Many rivets were loosened, and a few connecting the angle irons were sheared; also the outer skin was slightly indented. No damage was done to the condenser or Kingston valves.

Experiment in the Sea of Marmora, 1875.—This experiment was carried out by Turkish officers attached to their naval school at Halki, an island in the Sea of Marmora, about eight miles from Stamboul. It consisted in destroying a Turkish schooner by the explosion of an 100-lb. gun-cotton mine in contact with her, moored in 58 feet of water, and 10 feet beneath the surface.

Experiment at Carlscrona, Sweden, 1876.—This experiment was a continuation of those previously carried out in 1874-75, and which have been detailed at page 224, &c.

Target:—The same as had been used for the previous experiments (1874-75), and which had been thoroughly repaired.

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.

1st Experiment.

Torpedo:—60 lbs. of gun-cotton in slabs, saturated with water. Total weight of charge 75 lbs. It was enclosed in a 1/4" iron case with cast iron ends. It was placed at 15' actual distance from the nearest side of the case to the target, and opposite No. 4 frame on the port side, 10' below the surface of the water.

Effect of the explosion:—The effect upon the vessel was unappreciable. This charge represented the large Whitehead fish torpedo, and its position corresponded to that of this torpedo when striking a net at a small angle with the keel.

2nd Experiment.

Torpedo:—The Harvey towing torpedo, charged with 66 lbs. of gunpowder, primed with gunpowder, and fired by means of an electric fuze. It was placed at 3' actual distance from the target, measuring from the centre of the torpedo, and opposite No. 4 solid frame on the starboard side, the vertical axis of the torpedo being at right angles to the vessel's side, 9-1/4' below the surface of the water.

Effect of explosion:—This and the two following torpedoes were fired simultaneously. The outer bottom was blown in from the upper edge of the flat keel plate to the underside of the water-tight longitudinal, and fore and aft from No. 2 to No. 6 frames; an area 16' × 8-5/6'. Flat keel plates were broken between No. 2 and No. 4 frames, and the 4th strake of the bottom plating was broken, and the frames for that space blown in. Two holes were blown through the inner bottom, measuring respectively 2' × 2' and 7' × 1', making the total area of the inner bottom destroyed, 11 square feet.

3rd Experiment.

Torpedo:—33 lbs. of granulated gun-cotton, saturated with water; total weight of charge being about 41 lbs. It was enclosed in a 1/4" iron case, 12-1/2" × 12" × 12-1/2", the primer being 2-1/2 lbs. of slab gun-cotton, included in the 33 lbs. It was placed at 4' actual distance from the target, measuring from the centre of the case, and opposite No. 30-1/2 solid frame on the starboard side; 9-1/4' below the surface of the water.

Effect of explosion:—Outer bottom blown in from upper edge of the lower longitudinal to the lower edge of the upper longitudinal between Nos. 28 and 32 frames; an area of 18 × 11 feet. The butts of the flat keel were started and the plating broken across No. 30-1/2 frame from the flat keel plate to the upper deck. Shelf plate at Nos. 30-1/2 and 32-1/2 frames was broken. Nos. 29, 30, and 31 frames were blown in from first to third longitudinal; lower longitudinal from No. 28 to 31 also blown in. Two holes were blown through the inner bottom, measuring respectively 6 × 1·5' and 5' × ·25', making the total area of inner bottom destroyed 10 square feet. A steam launch with steam up and outrigger torpedo gear in place, one pole being rigged out, was placed with the stem of the boat 22' horizontally from the torpedo. She was uninjured and shipped very little water.

4th Experiment.

Torpedo:—31 lbs. 14 oz. of gun-cotton in slabs, saturated with water, total weight about 40 lbs. It was enclosed in a 1/4" iron case 12-1/2" × 12-1/2" × 6"; primer being 20 oz. of gun-cotton, included in the 31 lbs. 14 oz. It was placed at 4' actual distance from the target measuring from the centre of the case, and opposite No. 30-1/2 solid frame on the port side; 9-1/4' below the surface of the water.

Effect of explosion:—Outer bottom and frames injured in a similar manner to that described in the third experiment. Outer angle irons of the 1st, 2nd, and 3rd longitudinals were started in the wake of the broken place. A hole was blown through the inner bottom, measuring 9·5' × 1', or about 10 square feet in area. The bolts of the outer bottom plate of stern post much open, and at Nos. 16 and 17 on the port side the upper two strakes were buckled and the shelf plate started.

A steam launch, arranged in the same manner as in the fourth experiment, was uninjured, and shipped but little water.

Experiments with Countermine.—The following experiments have been carried out in England and other countries to ascertain some reliable data for countermining operations.

1st Experiment.

Experiments in the Medway, England, 1870.—Countermine:—432 lbs. of compressed gun-cotton, enclosed in a 3/16" iron case. It was moored at a depth of 37' below the surface of the water.

Submarine mines:—A series of similar cases containing coal dust, &c., were moored at distances of 50' to 100' from the countermine, and 37 feet below the surface.

Effect of explosion:—The submarine mine at 80' distance was completely destroyed; the dome of its circuit closer was dented in.

2nd Experiment.

Countermine:—As before, but moored 27' below the surface.

Submarine mines:—As before, but moored at distances of 70' to 120' from the countermine, and 27' below the surface.

Effect of explosion:—The submarine mine case at 120' distance was dented, but remained water-tight; the copper guard of fuze piece collapsed, and the earth connection of the fuzes was ruptured; the dome of its circuit closer was dented.

3rd Experiment.

Countermine:—As before, but moored 47' below the surface.

Submarine mines:—As before, but moored at distances of 70' to 200' from the countermine.

Effect of explosion:—The submarine mine case at 200' distance was dented, but it did not leak.

1st Experiment.

Experiments at Stokes Bay, England, 1873.—Countermine:—500 lbs. of gun-cotton, enclosed in a 3/16" iron case. It was placed on the ground, in 47' of water.

Submarine mines:—Six ground mines, 1/4" thick cases, fitted with circuit, 10' below the surface, at distances of 100' to 200' from the countermine.

Effect of explosion:—Submarine mines at 100' and 120' distance were destroyed, and their circuit closers thrown out of adjustment; submarine mines at 140' and 170' distance were much bulged, and leaked, and their circuit closer spindles were bent; submarine mine at 200' distance was uninjured, but its circuit closer was thrown out of adjustment.

2nd Experiment.

Countermine:—100 lbs. of gun-cotton enclosed in case, thickness No. 12 B. W. G. It was moored 10' below the surface, in 35' of water.

Submarine mines:—Five similar mines placed at same depth, at distances of 50' to 150' from the countermine.

Effect of explosion:—The submarine mine at 50' distance showed continued or dead earth, two screws broken, and its case dented; the other mines were uninjured.

1st Experiment.

Experiments at Carlscrona, Sweden, 1874.—Countermines:—226 lbs. of dynamite, enclosed in a case 17-1/2" × 20" × 1/8". It was moored 9-3/4' below the surface, the depth of water being 41 feet.

Submarine mines:—(a) cast iron ground 600 lb. mines, dome shaped, 48-3/4" × 21-1/2" × 2"; (b) cylindrical cases, wrought iron, empty, 11-1/2" × 11-1/2" × 1/8"; (c) cylindrical cases, wrought iron, charged, 11-1/2" × 11-1/2" × 1/8"; (d) cylindrical cases, wrought iron, 30-1/4" × 30-1/4" × 1/8"; (e) spherical cases, wrought iron, 32-1/2" × 1/8"; (f) spherical cases, tinned steel, 12" × 1/8".

Effect of explosion:—(b) mine, at 34' distance, was destroyed, and one at 92' distance was slightly bulged; (c) mine, 58' distance, mouthpiece injured and case leaky; (d) mine, 244' distance, a rivet started.

2nd Experiment.

Countermine:—As before, but moored at 29-1/4' below the surface; depth of water, 41 feet.

Submarine mines:—As before.

Effect of explosion:—(a) mine, at 146' distance, split in two; (b) mine, 34' distance, destroyed; at 49' distance, fractured; at 68' distance, indented but not fractured; (c) mine, 58' distance, case much bulged, and leaky; (d) mine, at 244' distance, rivets started, case half full of water; at 195' distance, sunk, several rivets started; (e) mine, at 195' distance, bolt loosened; (f) mine, at 68' distance, not injured.

3rd Experiment.

Countermine:—453 lbs. of dynamite, enclosed in a case, 24-1/2" × 28-1/4" × 1/8". It was moored 9-3/4' below the surface; depth of water as before.

Submarine mines:—As before.

Effect of explosion:—(b) mine, at 49' distance, sunk and not recovered; at 58' distance, very much indented; (c) mine, at 58' distance, case much indented and leaky; (f) mine, at 48-1/2' distance, uninjured.

4th Experiment.

Countermine:—As before, but moored 29-1/4' below the surface.

Effect of explosion:—(a) mine, at 195' distance, completely stove in; (c) mine, at 58' distance, case indented but charge dry; (e) mine, at 175' distance, slightly leaky; (f) mine, at 48-1/2' distance, upper half indented in three places. It was also discovered during the above experiments that submarine mines charged with dynamite can be caused to explode by the detonation of a charge of the same explosive, at distances from it considerably beyond those at which the cases themselves are damaged by a similar charge. To prevent the foregoing, it is necessary to pack the dynamite very carefully, using at the same time special precautions.