OUR COAST DEFENSES.

General H.L. Abbott delivered a lecture before the Academy of Sciences in New York, on the evening of March 21, a summary of which is given by the Herald as follows:

According to General Abbott, the country needs for its coast defenses:

The lecturer said that this nation may be attacked in four ways: First, by fleet and army combined, as in our revolutionary war; second, by blockading the entrances to all our ports; third, by bombardment of our seaport cities from a long distance; fourth, by a fleet forcing its way into our harbors, and making a direct attack or levying tribute on our people.

The first is not now greatly to be feared. We are too distant from great powers, and too strong on land.

The second should be met by the navy, and is, therefore, outside a discussion of coast defenses.

The third is not probable, though it may be possible. The extreme range of 10 miles for heavy guns cannot be obtained from shipboard, and as an elevation of only 15° or 16° can be given, not over 5 to 6 miles range is attainable.

The fourth is the one which is possible, probable, even certain—if we have war before we have better defenses.

The race between guns and armor began about thirty years ago, and there has been more development in ships and guns in that time than in the two hundred preceding years. The jump has been from the 7 in. rifle as the largest piece to the 110 ton Armstrong; in armor, from 4½ in. of iron to the Inflexible with 22 in. of steel plating. The new Armstrong gun of 110 tons, tried only recently, with 850 pounds of powder and an 1,800 pound shot can pierce all the targets, and so far guns have the victory over armor. This gun developed 57,000 foot tons of energy, and will probably reach 62,000. Imagine the Egyptian needle in Central Park, shod on its apex with hard steel, dropped point downward from the height of Trinity steeple; it weighs 225 tons, and it would strike with just about the effect of one of the 110 ton gun's projectiles. Two of these guns are ready for the ironclad Benbow, and the Italians have several equally powerful of 119 tons from Herr Krupp. The most powerful gun in the United States, the 15 in. or the 12 in. rifle, has a muzzle energy of 3,800 foot tons.

Ships like the Inflexible are the most powerful afloat. A steel water-tight deck extends across the ship, and she has 135 water-tight compartments. Her guns and engines amidships have a protection of 24 in. of armor, and amidships she has a citadel carrying two revolving turrets, each containing two 80 ton guns. Her turret armor is 18 in. thick. She can make 14 knots, and she has cost $3,500,000. But she has a low freeboard, and the guns, therefore, get no plunging fire.

The French ship Meta has her heaviest guns mounted en barbette, high above the water line, giving a splendid plunging fire.

Either of these ships could enter any of our harbors and hold us at her mercy.

The entrance to the harbor of Alexandria, Egypt, is about 5 miles across. At the time of the bombardment the protecting fortifications were situated at the east end, in the center, and at the west end. On the west there were mounted 20 modern guns of great size and power, and there were 7 others at the east end.

Although the Egyptians fought bravely, they did very little harm to the English fleet, while on the second day the defense was silenced altogether. Following the bombardment—as in Paris—came the reign of mob law, doing more harm than the shells had done; and it is a possibility that every such bombardment would be followed by such an overthrow—at least temporary—of all forms of law and order.

The ships that had silenced the Alexandria batteries—which had 27 heavy guns more than we have—could reach our coasts in 10 or 12 days, and we would have nothing to meet them.

Armor-clad casemates are beginning to take the place of masonry. A tremendous thickness of masonry is built up to the very embrasures for the guns in the steel-clad turrets. This (the Gruson) system has been adopted by Belgium, Holland, Germany, Austria, and Italy.

In 1882 England had 434 heavy modern guns behind armored shore batteries; besides these at home, she had 92 in her colonies, of which 13 were in Halifax and 11 in Bermuda—for our express benefit.

What we have are brick and stone casemates and earthworks. A sample granite casemate, with iron-lined embrasure, was built at Fortress Monroe, and 8 shots were fired at it from a 12 in. rifle converted from an old 15 in. smooth bore. This gun develops only 3,800 foot tons of energy—a mere nothing compared with the 62,000 foot tons of the English and German 110 ton guns.

General Abbott showed most conclusive proof of the worthlessness of masonry forts in pictures showing the effect of the shots. The massive 8 feet thickness of granite was pierced and battered till it looked like a ruin. Not a man inside would have been left alive.

He also showed a "disappearing" gun in an earthwork, the gun recoiling below the level of the parapet and being run up to a firing position by a counterweight. In 1878 Congress stopped all appropriations for defenses, and nothing had been done since.

General Abbott said that we needed submarine mines or fixed torpedoes, which should be thickly interspersed about the channel and be exploded by an electric battery on shore. To prevent these torpedoes from being exploded by the enemy, the surface over them should be covered by plenty of guns. Heavy guns and mortars were needed to resist attacks by heavy iron-clads. Movable torpedoes were valuable, but only as an auxiliary—a very minor auxiliary—compared with submarine mines. We should be cautious not to infer that torpedoes made a satisfactory defense alone, as they must be protected by large and small guns, and they form only a part of the chain of general defenses.

THE STEAMSHIP GREAT EASTERN.[[1]]

The history of the Great Eastern is full of surprises. It is always that which is most unlikely to happen to her which occurs. Not long since we recorded her sale by auction in Liverpool for £26,000. It was stated that her purchasers were going to fit her out for the Australian trade, and that she would at once be sent from Dublin to Glasgow to be fitted with new engines and boilers, and to undergo thorough renovation. Lord Ravensworth, in his address to the Institution of Naval Architects, spoke recently of the bright future before her in that Australian trade for which she was specially built. Yet at this moment the Great Eastern is lying in her old berth in the Sloyne at Liverpool, and unless something else at present quite unforeseen takes place, she will once more play the undignified part of a floating music hall. It seems that although she was certainly sold, as we have stated, the transaction was not completed. Her owners then cast about for the next highest bidder, who at once took her. He is, we understand, a Manchester cotton spinner, and he paid £25,500 for her. It is no secret that Messrs. Lewis made a considerable sum out of the ship last year, and the knowledge of this fact has no doubt induced her present owner to follow their example. The ship left Dublin on Sunday, April 3, under her own steam and in tow of two Liverpool tugs, the Brilliant Star and the Wrestler, and arrived in the Mersey without accident on Monday, after a passage of only thirteen hours. Mr. Reeves, formerly her chief officer, has been made captain. Mr. Jackson is still chief engineer. We cannot at present explain the fact that she went more than twice as fast as she has done recently, her engines making as many as 36 revolutions a minute, save on the assumption that while lying at Dublin much of the enormous growth of seaweed on her bottom died off, as will sometimes happen as a result of change of water. Her engines and boilers, too, have had a good overhaul by Mr. Jackson, and this may account in part for this improvement. It is much to be regretted that the scheme of using the ship for her legitimate purpose has not been carried out. It is not, however, yet too late. The Great Eastern was not a success in Dublin, for one reason, that a beer and spirit license could not be obtained for her. It is said that notice has been given at the Birkenhead police court that any application for a license of a similar kind will be opposed. Whether the ship will be as popular a resort without as she was with a license, we cannot pretend to say; and we may add that all our predilections are against her degradation to the status of a floating music hall. The greater her failure as such, the greater the chance of her being put to a better use; and it may help to that desirable end if we say here something concerning the way in which she could be rendered a commercial success as a trader.

It may be taken as proved that the present value of the ship is about £26,000. Mr. De Mattos gave, we understand, £27,000 for her, and he bought her by auction. The last sale gives nearly the same figures. If we assume that there are 10,000 tons of iron in her, we may also assume that if broken up it would not fetch more than £3 a ton at present rates; but even if we say £4, we have as a total but £40,000. To break the ship up would be a herculean task; we very much doubt if it could be done for the difference between £26,000 and £40,000; her engines would only sell for old iron, being entirely worthless for any other place than the foundry once they were taken out of her; as for her boilers, the less said about them the better. In one word, she would not pay to break up. On the other hand, by a comparatively moderate further outlay, she might be made the finest trading ship afloat. There are two harbors at all events into which she can always get, namely, Milford and Sydney. There are others, of course, but these will do; and the ship could trade between these two ports. By taking out her paddle engines, she would be relieved of a weight of 850 tons. The removal of her paddle engine boilers would further lighten her, and would give in addition an enormous stowage space. By using her both as a cargo and a passenger ship, the whole of the upper portion could be utilized for emigrants, let us say, and the lower decks for cargo, of which she could carry nearly, if not quite, 20,000 tons. She would possess the great advantage that, notwithstanding she was a cargo ship, she would be nearly, if not quite, as fast as any, save a few of the most recent additions to the Australian fleet. There is every reason to believe that she has been driven at 14 knots by about 6,000 horse power. We are inclined to think that the power has been overstated, and we have it on good authority that she has more than once attained a speed of 15 knots. Let us assume, however, that her speed is to be 13 knots, or about fifteen miles an hour. Assuming the power required to vary as the cube of the speed, if 6,000 horsepower gave 14 knots, then about 4,800 would give 13 knots—say 5,000 horse power. Now, good compound engines of this power ought not to burn more than 2 lb. per horse per hour, or say 4.5 tons per hour, or 108 tons a day. Allowing the trip to Australia to take forty days, we have 4,320 tons of coal—say 5,000 tons for the trip. The Etruria burns about this quantity in the run to New York and back. For each ton of coal burned in the Great Eastern about 15,000 tons of cargo and 3,000 passengers could be moved about 3-1/3 miles. There is, we need hardly say, nothing afloat which can compare in economy of fuel with this. Taken on another basis, we may compare her with an ordinary cargo boat. In such a vessel about 3,000 tons of grain can be moved at 9 knots an hour for 600 horse power—that is 5 tons of cargo per horse power. Reducing the speed of the Great Eastern to 9 knots and about 2,000 horse power, we have 9 tons of cargo moved at 9 knots per horse power; so that in the relation of coal burned to cargo moved she would be nearly twice as economical as any other vessel afloat.

The important question is, What would the necessary alterations cost? Much, of course, would depend on what was done. A very large part of the present screw engines could be used. For example, the crank shaft, some 2 feet in diameter, is a splendid job, and no difficulty need be met with in working in nearly the whole of the present framing. If the engines were only to be compound, two of the existing cylinders might be left where they are, two high-pressure cylinders being substituted for the others. If triple expansion were adopted, then new engines would be wanted, but the present crank and screw shafts would answer perfectly. The present screw would have to be removed and one of smaller diameter and less pitch put in its place. All things considered, we believe that for about £75,000 the Great Eastern could be entirely renovated and remodeled inside. Her owners would then have for, say, £100,000 a ship without a rival. Her freights might be cut so low that she would always have cargo enough, and her speed and moderate fares ought to attract plenty of passengers. Sum up the matter how we may, there appears to be a good case for further investigation and inquiry as to the prospects of success for such a ship in the Australian trade, and the opinion of merchants and others in Melbourne and Sydney ought to be obtained. Something would be gained even if the opinions of unprejudiced experts were adverse. We might then rest content to regard the ship as an utter failure, and not object to see her sunk and filled with concrete to play the part of a breakwater. Until, however, such an opinion has been expressed after full discussion, we must continue to regard the ship as fit for something better than a music hall and dancing saloon.—The Engineer.

[1]

See Engraving in SUPPLEMENT NO. 584.