well defended ports on the Atlantic coast. In the Mediterranean, the ports of Barcelona and Carthagena have the protection of outlying forts of considerable strength and importance, and Cadiz is a fortress of the first class, surrounded by immensely powerful works, such as the batteries of La Soledad and Boneti, San Sebastien, Cortadina de San Fernando, and Torre Garda. The reduction of these fortresses would necessitate the employment of a vast naval armament, and of siege batteries, fully equipped, and only a military Power of great magnitude could venture to undertake the work. The half-trained levies of the United States, that are at best only a militia of not very high order, are no match for the disciplined troops of Spain, 200,000 of which at least have had much recent fighting experience, and the United States Navy would be fully employed in meeting its enemy upon the high seas.

To sum up. Although in point of numbers of ships, weight of armament, armored protection, speed and other factors, the navy of Spain is certainly not equivalent to that of America, we are inclined to think that the United States would have more to lose than Spain in the eventualities of a naval war; and if a serious reduction of the Spanish continental fortresses was taken in hand it would prove to be a very long operation indeed. The fighting that Spanish troops have been recently engaged in would give a favorable preponderance to that side.

-The Engineer, October 1,

MILITARY GEOGRAPHY.

Floating Dock for Havana.

1897.

The continued presence of a large fleet in Cuban waters necessitated some means of repairing and painting the same, and the Spanish authorities found themselves called upon at short notice to provide some form of dock for their vessels, there being no repairing establishment of any kind in the neighborhood. The older fashion of stone graving docks was quite out of the question as, irrespective of their great cost, the time required for their construction was quite prohibitive. A dock large enough to deal with their largest ironclads would have taken three years in building, and perhaps longer, a somewhat similar stone dock at Cockatoo Island having taken no less than seven years to build, whilst the Gibralter one seems likely to take nearly as long. Their attention was therefore called to the new forms of ship-repairing machines, such as floating docks, and accordingly, at the end of last year, tenders were invited for the installation at the port of Havana of a floating dock capable of dealing with vessels up to 500 ft. long and displacing up to 10,000 tons. From amongst the different tenders set in, that presented by Messrs. Swan and Hunter, of Wallsend-on-Tyne, was the one accepted. This firm proposed a new form of floating graving dock introduced but a short time previously by Messrs. Clark and Stanfield in a paper read before the Institution of Naval Architects. The type had been introduced by this firm specially with a view to coping with the short and heavy ironclads of which modern navies are so largely composed, whilst still retaining the ordinary advantage of a floating dock in being able to take also light and long vessels such a liners and cruisers.

The dock, which was successfully launched last Saturday afternoon, consists of five rectangular pontoons, of which the two terminal ones have pointed ends. These pontoons are built of steel and are of great strength, as they carry along their centre line the whole weight of the 10,000-tons ship, which rests on a series of wooden keel blocks supported on transverse girders, which

gradually transmit this local weight over the whole area of the pontoons. The five pontoons are fastened on each side by a very strong form of double-joint between two other caissons running one along each side, and which projects up above their decks, giving the whole dock a U-shaped section. These caissons or walls, as they are termed, bind all the five pontoons into one whole, and being higher than these they also regulate their descent below water, and afford the dock stability when it is lowered down to allow the vessel to float in over the keel blocks. It is in the upper chambers of these walls that the machinery of the dock is contained, and it is from their top deck that all the manipulations of the dock are carried on. That is to say that the valves that regulate the admission of water into the different compartments of the dock are worked from here, and the bilge shores and side shores which hold the ship up on the dock and keep it from heeling are hauled in and out and fixed in position from here. The length of the walls is 338 ft. 4 in. and their height 44 ft. 2 in., so that the dock can take a vessel drawing 27 ft. 6 in. and still have a freeboard of 4 ft. 2 in. The pontoons are each 11 ft. 8 in. deep, 88 ft. broad, and the aggregate length of the five is 450 ft. The length of ship, however, that the dock can take is not limited by its length, as there are no gates closing its ends, as in the case of the ordinary graving dock, but vessels of a much greater length than 450 ft. can be lifted, and in urgent cases floating docks have been known to lift vessels double their own length. End gates or caissons are, however, provided, which can be used with this dock when short heavy ironclads are dealt with, and by means of these the lifting power of the dock can be considerable increased, and, what is more important, longitudinal strains may be avoided, as the effort of lifting can be confined exactly to that portion of the dock which lies under the ship, so that the latter is as equally borne as if it were on the most solid stone foundation.

An interesting point about this dock is that electricity has been used as the motive power for pumping out the water from its compartments. The power is generated by two of Messrs. Scott and Mountain's compound vertical engines, each driving direct on to a Tyne dynamo. These engines are placed one in each wall, but the cables are so connected that either engine can send power to the opposite side in case of breakdown. From the diagrams the power is transmitted to five mortors in either wall, each of which drives by a shaft one of Messrs. J. and H. Gwynne's centrifugal pumps placed at the bottom of the side, which are of the centrifugal type but driving horizontally. Both motors and pump shaft are run on steel balls like bicycle bearings, so that there is but little friction. The power generated is sufficient to lift a vessel weighing 10,000 tons in 21⁄2 hours, but it is one of the advantages of a floating dock that smaller vessels can be lifted in proportionately less time, and also at a proportionately less expenditure of power, being in this respect the direct opposite of a graving dock, where the smaller the vessel the greater the amount of water to be pumped. We have mentioned earlier the great advantage that this type of dock offers in the way of speed in building. The contract for the present dock was signed at the beginning of December last; the drawings and quantities had to be got out and the material ordered, whilst in this case special machinery was also put down, with the result that it was not until the beginning of March that the first plate was laid. The dock is launched in a fine condition, and in the course of next week will take its departure for Havana. Had it been intended for use on the Tyne it would have been capable of commencing its work and lifting ships within six months of the laying down of the first plate. It is hardly necessary to accentuate the

advantage of time in the present case, or to point out how this compares with the time required to build a stone dock.

At the launch the Admiralty was represented by Sir William White, who made a careful survey of the dock, and it is possible that in this novel development of steel construction applied to docks they will find the solution of the problem of providing speedily and at a low cost the numerous docks so much required in all our foreign possessions.

The dock is expected to arrive in Havana within six weeks of her departure, when she will at once commence her regular work of docking vessels, so that within II months of the Spanish Government deciding on acquiring one of these modern machines they will be provided with one capable of dealing with the heaviest vessels in their Navy.

-The Army and Navy Gazette, September 4, 1897.

War Ships and Torpedo Boats.

The Italian Cruiser Giuseppe Garibaldi.

The Ansald ship-yards at Sestri-Ponente launched on the 27th of September last an armored cruiser, the Giuseppe-Garibaldi, built for the Italian govern

ment.

This new cruiser is in every respect similar to that which had previously been built at the same works, and which was turned over to the Argentine Republic, bearing the name of Garibaldi. It also resembles the Varese, launched on the 25th of July at Leghorn, at the Orlando ship-yards. The Giuseppe-Garibaldi has a displacement of 6840 tons and the following principal dimensions:

The triple expansion engines work two screws; the boilers are of the Belleville pattern; with natural draft 8600 horse-power is developed, with forced draft with 13,000 horse power she will attain a speed of 20 knots.

The capacity of the coal bunkers is 1000 tons, besides a considerable supply of petroleum.

The armament comprises two guns of 254 mm. in two armored turrets, protected by masks turning with them; ten of 152 mm. rapid fire, in battery in the central redout; six of 120 mm., rapid fire, on the upper deck protected by masks, and lastly ten of 57 and ten of 37 min., rapid fire, and two machine guns, Nordenfeldt, in the top.

Five submerged torpedo tubes.

-Le Yacht, October 16, 1897.

Launch of H.M.S. Canopus.

The first-class battleship Canopus, and the first of her type afloat, was successfully launched at Portsmouth upon Wednesday last from the famous old building slip which has borne the cradles of the Trafalgar, Vulcan, Royal Arthur, Eclipse, Prince George and Gladiator.

This vessel is one of a new class of battleships, designed by Sir W. H. White, K.C.B., three of which are building in the Royal Dockyards, and three by contract. They were originally called "improved Renowns," as their designed displacement approximated most nearly to the tonnage of that ship, but their disposition of armor, armament, and internal arrangements correspond more

closely to those of the Cæsar, and they will somewhat resemble that battleship when completed.

The dimensions, etc., are as follows: Length between perpendiculars, 390 ft.; ditto over all, from taffrail to ram point, 427 ft.; beam, extreme, 74 ft.; mean draught, 26 ft.; displacement, 12,950 tons; speed, estimated, about 18.5 knots. This last will probably be exceeded by at least one knot. The Canopus will be fitted with twin screws, each driven by an independent set of triple-expansion engines, built at the Greenock Foundry, with three vertical cylinders of the collective horse-power of 6750, giving an aggregate indicated horse-power of 13,500 for both sets of engines. The boiler safety valves will be loaded to a pressure of 300 lb. per square inch, the steam pressure being reduced to 250 lb. per square inch at the engines. Unlike those in vessels of the Majestic type, the boilers will be of the Belleville pattern, the first to be fitted in any of H.M. battleships. They will be twenty in number and will be completed with all the latest improvements. Each boiler will be capable of being used independently of the others. The ship has bunker capacity for stowing 1900 tons of coal; her coal supply at load draught will, however, be only 800 tons. Her launching weight was about 4500 tons, none of the side or barbette armor being in position as yet.

The disposition of the protective armor is, as before remarked, similar to that of the Majestic type, combining the advantages of the turtle-back decks of the cruisers with those of the citadel armor of previous battleships. The vertical armor varies in thickness from 12 in. to 6 in., and is formed of steel plates treated by the Harvey process, which greatly increases their resistance to penetration. Protection is afforded by this armor to the machinery, guns, &c., as well as by an armored deck extending from stem to stern, which is 3 in. thick in the stoutest flat part. Thus the vitals of the vessel are shielded by an equivalent of 12 in. of specially prepared steel-the sloping 4 in. flanks of the armored deck giving an auxiliary thickness to the vertical 6 in. armored walls of 6 in.-and 12 in. of such steel with a hardened face will stop the 12 in. projectile, or break it up, being equivalent in stopping power to 30 in. of wrought-iron. The barbettes are covered with 12 in. Harveyed steel plates, so that their armor is equivalent to that of the side armor and oblique armored deck combined.

But another increment of protective strength has been afforded to this vessel by an armored main deck, extending also from stem to stern. This has two 20 lb. steel plates worked upon it, in lieu of the ordinary sheet steel, making a thickness of 1 in. altogether, independently of the turtle-back lower deck underneath. The vessels of the Andromeda class and many French ships have been treated in this manner, the only difference in the foreign ships being in the circumstance that they have the thick deck above and the thin one below, whilst we reverse the positions of the two. Advantage has been taken of the alteration in the main deck and of the teaching of the battle of Yalu to eliminate wood altogether from this deck. There is, therefore, no' wood planking upon this feature of the Canopus; the 1 in. armor is now a smooth expanse without a rivet-head showing, but it is to be sheathed with composition for walking on. The forward conning tower, which is covered with 12 in. steel plates, does not stand over the thin end of a pear-shaped barbette, as in the Majestic and Magnificent. But the barbette being round, as in the Casar, a separate armored stalk is provided beneath the conning tower which carries the voice tubes and other gear to be connected.

A special feature of the Canopus type is the ram bow, the point of which is much higher than in former battleships, being only 7 ft. 6 in. below the surface of the water at normal draught, so as to deliver a blow to the enemy immediately below the armored belt. The forefoot comes away at an abrupt angle from the keel, 45 ft. horizontally from the ram point, the flat keel rising from a spot just forward of one of the main bulkheads, and running straight to the ram, as will be seen by a reference to the profile engraved. The armored deck, which has a perfectly horizontal outer edge on either beam from stem to stern, is worked into the cast steel stem a very short distance above the point, and an ordinary flat, terminating in a stiffening plate of steel 2 in. thick, is bedded into the point itself. The whole of this portion of the bows is, moreover, to be covered with 2 in. nickel-steel armor plates over the ordinary skin. None of this armor is in position yet, but the rabbet into which it will fit can be seen running up the stem on both sides. The ram is, therefore, with its associated parts, a solid cellular mass, extending to a main bulkhead about eight frames from number "o," which is the first, and its materials are stiff as well as elastic, the whole being supported by the cast steel stem, by the armored deck, by the stiffening plate beneath, and by the 2 in. nickel-steel armor plates, as well as by the ordinary skin and framing of the ship at this spot.

About nine of the forward frames are webbed right across with thin steel plates, so as practically to constitute a series of bulkheads at 3 ft. intervals. The spaces between are filled in with cork, from the keel below to the main deck above, as shown in our profile, a device already employed in the Inflexible, the Colossus and Edinburgh. It may be remembered that the three battleships of the United States now under construction, the Wisconsin and her sister vessels, described in the pages of The Engineer some months ago, have large spaces behind the ram filled in with corn-pith cellulose, so that the American and British war vessels assimilate in this respect.

Two steel masts will be fitted, each completed with a fighting top; these latter will carry three 3-pounder quick-firing guns, with the necessary magazines and equipment. Above the fighting top an electric light platform will be fitted to each mast for working powerful search-lights. The topmasts are