had been withdrawn from the first battle line in order to provide material for submarine construction. "In reality, the withdrawal from the first line was effected because the pre-dreadnought type is absolutely useless in a modern artillery battle. For this reason the British did not put their squadrons of older ships in their battle fleet, and for the same reason Admiral Scheer, after the experience of the Skagerrak, decided to withdraw them from the first line. That from the material of some older ships nickel had been obtained for submarine construction has nothing to do with this withdrawal."-Engineer, 10/1.

SUBMARINE TONNAGE FIGURES.The battleship Baden is due at Scapa Flow this week, and with her arrival the surrender of the German surface warships, as stipulated in the armistice, will be complete, the battleship Koenig and the light cruiser Dresden having been delivered early in December.-Engineer, 10/1.

GERMAN NAVAL TYPES.-Of the five German battle-cruisers now in custody at Scapa Flow, the latest and most powerful are the Derfflinger and Hindenburg, which, if outward appearance goes for anything, are sister-ships. There is, however, some doubt on this point, though the report that the Hindenburg carries eight 15-inch guns, as against eight 12-inch in the Derfflinger, remains unconfirmed. The Derfflinger was laid down at the Blohm and Voss yard, in Hamburg, in March, 1912, and completed a week or two before the outbreak of war. Her dimensions and other particulars are as follows: length (on water-line), 689 feet; beam, 95 feet; mean draft, 271⁄2 feet; normal displacement, 26,600 tons. The propelling machinery consists of "Marine" type-modified Parsons-turbines, driving four screws, and supplied by 18 Schulz-Thornycroft boilers, all of which are coal fired. The contract called for 63,000 horse-power and 26.5 knots, but those figures are nominal only. The maximum fuel supply amounts to no less than 4700 tons, including about 600 tons of oil. Like all German battle-cruisers, the Derfflinger carries a great weight of armor. The main belt, 12 inches thick, is surmounted by an upper strake of 8-inch armor, above which again is the 5.9-inch battery protected by 7-inch armor. The extremities of the ship are clothed with 4-inch or 5-inch plating as high as the main deck. At each end of the main belt there is a 10-inch transverse bulkhead, and two protective decks are fitted with an aggregate thickness of seven inches over boiler, machinery, and magazine spaces. The main battery comprises eight 12-inch 50 caliber guns, disposed on the center-line, all the guns having a wide arc of fire. Twelve 5.9-inch Q. F. are mounted in the upper deck battery, and there is a number of 3.4-inch Q. F., including several on A.-A. mountings, in the superstructure. The Derfflinger is heavily built up amidships, in contrast to the low freeboard at bow and stern. The large fore tripod carries a fire-control station, in the upper section of which a range-finder will be observed.-Engineer, 17/1.

THE GERMAN SUBMARINE "U. B.-64."—An opportunity having been given by the Admiralty for certain members of the public to inspect the German submarine U. B.-64, moored off the Terrace of the House of Commons, a description of the construction of this enemy submarine will doubtless prove of considerable interest to all of us.

To those who have tried to follow the trend of German submarine construction without inside information, the prefix "U. B." has always been taken to denote a small coastal submarine of a rather primitive type, as exemplified by the photographs which the French Government allowed to be published of the captured U. B.-26 in dry dock. The dimensions of U. B.-64, therefore, came as something of a shock, for there seems to be little difference in size between her and the U-boats which we knew before the war.

Hull.-Like all modern submarines, she is constructed in the form of an inner cylindrical pressure-resisting hull on to which is built an outer hull of light plating. The water flows freely into the space between the inner and outer hulls, and therefore the plating of the outer hull is not subjected to any particular pressure. The inner pressure hull and the conning tower built on to it is the submarine proper, the outer hull being nothing but a light superstructure, built in the form of a ship designed to make her a passable sea boat when traveling on the surface, and to give a practicable deck. This ship hull has a very fair freeboard forward with a cutaway stem. The deck sheers considerably, has a flush midship section, and then drops until it is awash aft. It is of wood, the planks being spaced in order to offer no obstruction to the free flooding.

In order to neutralize our net barrages, a heavy saw-edged knife is fitted to the top of the stem, raking aft at an angle of about 45 degrees, and being supported by two steel struts. From this cutter two wires are led over fairlands on the conning tower and are secured to the deck aft, their object being to lift any obstruction or sweep clear of the vessel. A portion of their length before and abaft the conning tower is insulated to allow of their being used for wireless. The main wireless aerials are

GERMAN U-BOAT.

supported by two tall masts with quadrant heels, which are raised and lowered by means of wires from the interior of the boat. The after mast is fitted with rungs to enable it to be used as a lookout station. Normally they lie flat along the deck, which is recessed to take them.

On either side of the hull are the ballast and fuel tanks, the rounded tops of which make the "cigar-shaped hull" which shows in all the published photographs. As the fuel is used the tanks are allowed to fill with sea water in order to maintain the trim of the boat. It would appear that any or all of the ballast tanks can be filled with fuel oil to increase the radius of action, but, of course, the fuel would all be lost should it be necessary to empty the tanks hurriedly.

Conning Tower.-The conning tower, which is placed roughly amidships, seems very large for the hull, and is stream-line shaped with a sharp forward edge. It is surmounted by a permanent steel wind screen enclosing the "bridge," which does not, however, extend to the forward end of the conning tower, a steering position being exposed before it. The reason of this arrangement is not quite clear. The two periscopes pass through the conning tower and have a peculiar feature in that near the top they are suddenly thinned down, until their diameter is certainly not more than three inches. The value of certain published stories of a

i

few inches of periscope being sighted at 500 yards is demonstrated when the diameter is seen. One of these periscopes has the top of its casing cut away in such a manner that it is evidently designed for watching aircraft. Inside the conning tower is one of the control stations, from which the forward periscope is worked. The after-periscope is contained in a steel shaft. Scuttles are fitted in the sides of the tower and are embrasured in such a manner that the officers inside can command a view right ahead. Just forward of the gun a piece of metal is hinged on to the deck, which, when opened, exhibits a large white ring. This is doubtless an identification mark for aircraft.

Gun.-A few feet before the conning tower a 3.4-inch (22-pounder) gun is fitted on a noticeably low pedestal. Judging from the elevation which its mounting permits it to be given, this gun should have a range which goes a long way to explain the frequency with which it was reported that the Huns contrived to outrange the guns carried by our merchantmen. Just abaft the gun there is a locker, under the deck, for a few rounds of ready ammunition, each round being contained in a watertight metal case similar to the one now being exhibited by the Imperial War Museum at the Grosvenor Galleries. In the case of a prolonged action, ammunition has to be handed out through the conning tower. Although frequently mentioned in reports of merchant ships attacked, there is no sign of a machine gun on U. B.-64; but on the conning tower there is more than one mounting that might have been designed for a machine gun or a searchlight-or both.

Boat.-Stowed bottom upwards on deck aft is a collapsible boat capable of accommodating about four or five men.

Compressed Air Service.-Outside the pressure hull, but visible through the open flanking of the deck, are secured several steel bottles for compressed air. These are used chiefly for emptying the ballast tanks should it be necessary to come to the surface in a hurry.

Interior of Hull.-Working from forward the arrangement of the interior of the hull is as follows: Right forward there is a large ballast tank, extending the whole breadth of the vessel, through which pass the four bow torpedo tubes. Close to them are placed four torpedo compensating tanks, the object of which is to maintain the trim of the boat whenever a torpedo is fired by immediately admitting an equal weight of water into the hull. It has frequently occurred that badly trained German crews have not flooded these tanks smartly enough when a torpedo was fired, with the result that the submarine has lost her trim as a result of being suddenly relieved of the weight right forward, broke surface with her bow and immediately became the target of the guns of the convoy attacked.

Forward Mess Deck.-The compartment next to the forward ballast tank, into which the breeches of the tubes project, is the forward mess deck, where some members of the crew are accommodated. Round the walls of the compartment are ranged folding iron-framed bunks, a luxury undreamed of in British craft of similar type. It would appear, however, that a portion of the crew have to sling hammocks. In addition to the torpedo normally carried in each tube, there is stowage for four spares in this compartment. When a vessel of this type puts to sea with a full crew the mess deck, at least, must certainly be uncomfortably crowded. Several steel flasks containing oxygen at high pressure are stowed here and right aft.

Officers' and Warrant Officers' Messes.-Immediately astern of this compartment, and divided from it by a bulkhead with watertight door, there is a small mess for the warrant officers, furnished with two bunks and a settee, but with little else in the direction of comfort. This, again, is divided by a sliding wooden door from the ward room, which is a much more showy compartment. Here the walls and bulkhead are covered

with stained panelling and wall cupboards, with glazed doors, are fitted for crockery and gear. A small folding table occupies the centre of the ward room, but can be quickly unshipped when desired. Three very sizeable folding bunks and a settee complete the fittings. Altogether, considering the size of the vessel, very much more comfortable quarters could reasonably be expected. The after wall of the wardroom is a bulkhead with watertight door leading to the

Control Room and Auxiliary Engine Room.-This compartment is divided into two by a light partition with sliding door in precisely the same manner as the ward room and warrant officers' mess noted above. It is the nerve centre of the boat and is nothing more than a crowded mass of intricate machinery. It is rendered more crowded still owing to the space occupied by a large steel shaft, inside which the after periscope and its operator are raised and lowered together by means of electric motors. The forward half of the compartment is the control room, the usual submerged action station of the captain; all controls are led here, as well as to the conning tower. On the port side the wireless room is enclosed in a silence cabinet, but in view of the close proximity of the auxiliary machinery it is very doubtful if the cabinet ever really deserves the adjective. Under the floor is the magazine for 22 pounder ammunition, chain falls being slung on to the deck beams above the hatch for the purpose of hoisting it out. The auxiliary machinery is closely packed into the after portion of the compartment, a lavatory being curtained off on the port side.

After Mess Deck.-Abaft the auxiliary machinery there is another mess deck, fitted with eight bunks and hooks for slinging hammocks in the same way as the forward one. In this compartment the head room is judged to be slightly under six feet, which may be taken as a fair average throughout the boat. There is a bulkhead with doors of the usual pattern at either end.

Engine Room-In this type there is no division between the engine and motor rooms, the Diesel engines occupying the forward and the electric motors the after end of the longest compartment in the ship. The main engines are two 6-cylinder 4-cycle reversible Diesels, bearing the plate of the well-known M. A. N. firm. Judging from their appearance, they should develop about 500 b. h. p. each. The prize crew artificer in charge of the engine room was generous in his praise of the engines. Abaft the Diesel engines and on the same shafts are the two main motors for propelling the vessel under water. When the engines are being used on the surface the motors are either allowed to run free or else are employed as generators for charging the accumulators, which are stowed under the deck throughout the after part of the vessel. The cells are of the ordinary lead type, and do not appear to be any great improvement on our own. When running submerged the engines are disconnected by means of a friction clutch worked by hand. The switchboard is between the engines and motors and the control position is at the forward end of the motors. Petty Officers' Mess.-Next to the engine room is a small compartment for the use of the petty officers, three bunks being fitted. In one corner of it is the galley, a very compact little electric stove, that must make the atmosphere unpleasant, in spite of the fact that the after hatch, which is too near the water to be opened in anything but fine weather, leads directly into the compartment.

After Compartment.-This compartment contains the after tube and its accompanying fittings, and the electric motors for working the vertical steering rudder and the two after horizontal hydroplanes. There is an emergency hand gear to both the vertical and horizontal rudders, and it is believed by the prize crew that it was the German custom to use these in order to reduce noise when they had reason to believe that we had listening gear in the vicinity.

The general impression gained by an inspection of U. B.-64 is that the wonderful superiority of the German submarine designers over our own exists chiefly in the minds of certain members of the public. The totally different use to which their submarines were put caused them to pay very much more attention to the comfort of the men than in the British Navy, and in minor matters the German attention to detail and workmanship give them a distinct advantage. The machinery, periscopes, etc., are excellent and from all accounts they are splendid sea boats. But they are improvements on our own vessels of similar type only; they are not wonderful vessels that can do everything but fly. And under any circumstances, it must be remembered that U. B.-64, though right up to date, belongs to the smaller type.

Of the air-purifying apparatus of which so many wonderful and vague reports have appeared in the Continental press, there was no evidence, but in any case it would probably all be stowed away in a small box and might very easily escape notice.

The condition of the vessel when handed over was very bad and disgusted our men who took charge.-Marine Engineer and Naval Architect, January, 1919.

HOW IT HAPPENED.-On November 19, 1918, the well-known German military critic, Capt. Persius, published the following:

"The hope that the High Sea Fleet might in another Jutland battle be able to crush British naval supremacy, was merely based upon bluff and lies.

"In August, 1914, Germany had about a million tons of men-of-war as against England's 2.2 million tons.

"Thanks to Von Tirpitz's faulty constructional methods, German materials were inferior to the English. The German fleet was saved from a disastrous fate by Admiral Von Scheer's skilful orders and the clumsy manœuvering of Admiral Jellicoe, and the foggy weather which helped. If the weather had been clear and if both sides had had skilful commanders, the result would have meant our annihilation.

"The longer range English guns would have shot our weaker armed ships to pieces.

"The losses of our fleet were enormous, despite fortune favoring us, and in June, 1916, every expert saw clearly that this battle would and must become the only one.

"Tirpitz was attacked from all sides with the demand that only U-boats be built, but he remained silent. Finally, on October 1, the supreme army command was able to make their wishes felt by the members of the Reichstag-not by the Imperial Navy Department orders. Orders were given to cease building ships of the line and battle cruisers. U-boat material had now become so scarce that it had to be taken from the ships of the line in order to procure the requisite amount.

"During the beginning of 1918, 23 ships had in this manner been taken from the High Sea Fleet-among these there was one which had been launched in 1916, 8 armed cruisers, 8 armed coast vessels, 16 small cruisers, and among these one which was launched in 1911.

"This year, 1918, our High Sea Fleet consisted in battleships merely of dreadnoughts, ships of the line of the Nassan, Helgoland, Kaiser and Markgraf class, as well as some battle cruisers. Tirpitz putting all other vessels out of action was an admission that all other ships which he had built at the expenditure of millions between 1897 and 1906 were either useless or could not be used to fight British ships. Submarine warfare followed, for the weapons requisite for it practically did not exist. Capelle launched but a minimum quantity of U-boats. Had they been constructed, they would, as far as the larger U-boats are concerned, first have been ready for "action" in 1919 or 1920. In order to construct a large boat,