in pairs on the broadside.

Thus 8 12-in. guns (80 per cent. of the main armament) can be fired on either broadside, and 4, or possibly 6, 12-in. guns (or 60 per cent. of the main armament) can be fired simultaneously ahead or astern.

In view of the potentialities of modern torpedo craft, and considering especially the chances of torpedo attack towards the end of an action, it is considered necessary to separate the anti-torpedo boat guns as widely as possible from one another, so that the whole of them shall not be disabled by one or two heavy shells. This consideration led the Committee to recommend a numerous and widely distributed armament of 12-pr. Q.F. guns of a new design and greater power than those hitherto carried for use against torpedo craft.

In order to give the ship good sea-going qualities and to increase the command of the forward guns, a forecastle is provided, giving the ship a freeboard forward of 28 ft.- -a higher freeboard than has been given to any modern battleship.

The main armour belt has a maximum thickness of 11 in., tapering to 6 in. at the forward and 4 in. at the after extremity of the vessel; the redoubt armour varies in thickness from 11 in. to 8 in. ; the turrets and fore ; conning tower are 11 in. thick, and the after conning tower is 8 in. thick; the protective deck varies from 13 in. to 23 in. in thickness.

Special attention has been given to safeguarding the ship from destruction by underwater explosion. All the main transverse bulkheads below the main deck (which will be 9 ft. above the water-line) are unpierced except for the purpose of leading pipes or wires conveying power. Lifts and other special arrangements are provided to give access to the various compartments.

Mobility of forces is a prime necessity in war. The greater the mobility the greater the chance of obtaining a strategic advantage. This mobility is represented by speed and fuel endurance. Superior speed also gives the power of choosing the range. To gain this advantage, the speed designed for the Dreadnought is 21 knots.

The question of the best type of propelling machinery to be fitted was also most thoroughly considered. While recognizing that the steam turbine system of propulsion has at present some disadvantages, yet it was determined to adopt it because of the saving in weight and reduction in number of working parts, and reduced liability to breakdown; its smooth working, ease of manipulation, saving in coal consumption at high powers and hence boiler-room space, and saving in engine-room complement; and also because of the increased protection which is provided for with this system, due to the engines being lower in the ship: advantages which much more than counterbalance the disadvantages. There was no difficulty in arriving at a decision to adopt turbine propulsion from the point of view of sea-going speed only. The point that chiefly occupied the Committee was the question of providing sufficient stopping and turning power for purposes of quick and easy manoeuvring. Trials were carried out between the sister vessels Eden and Waveney, and the Amethyst and Sapphire, one of each class fitted with reciprocating and the other with turbine engines; experiments were also carried out at the Admiralty Experimental Works at Haslar, and it was

considered that all requirements promise to be fully met by the adoption of suitable turbine machinery, and that the manoeuvring capabilities of the ship, when in company with a fleet or when working in narrow waters, will be quite satisfactory.

The necessary stopping and astern power will be obtained by astern turbines on each of the four shafts. These astern turbines will be arranged in series, one high and one low pressure astern turbine on each side of the ship, and in this way the steam will be more economically used when going astern, and a proportionally greater astern power obtained than in the Eden and Amethyst.

The ship has a total coal-bunker capacity of 2700 tons, and with this amount of coal she will be able to steam about 5800 sea miles at economical speed, and about 3500 sea miles at 18 knots after allowance has been made for bad weather and for a small amount of coal being left in the bunkers. Stowage for oil-fuel has been arranged for, but oil-fuel has not been taken into account in estimating the radius of action, which, of course, will be greatly increased thereby.

Considerable attention has been devoted to the arrangements for the accommodation of the officers and men. In view of the increasing length and greater power of modern ships the usual position of the Admiral's and Captain's quarters right aft is becoming more and more open to objection. Up to the present the principal officers have been berthed at the furthest possible distance from the fore bridge and conning tower, where their most important duties are performed. It has been decided that in this ship the Admiral's and Captain's quarters shall be placed on the main deck forward, near the conning tower; also that the officers' quarters shall be placed forward, both on the main deck and on the upper deck, in the fore part of the ship. Ample accommodation for the remainder of the crew is available on the main and lower decks aft.

"Invincible" Class.

The principal dimensions of this class will be found below.

INDEX