MECHANICS AND USEFUL AIITS. 85 



and into the intervening space the guns will bo raised in order 

 that they may be loaded, while they will bo submerged in the 

 water, in order that they miy be discharged, from live to seven feet 

 below the water-level. Perhaps a somewhat different arrangement 

 may be adopted ; in any case, however, the guns must be capable of 

 doing damage below the water-level. 



Light wooden top-sides may be provided for the comfort of the 

 crew, and, perhaps, to deceive an enemy as to the real character of 

 the ship with which we would have to cope. A light draught of 

 water will be indispensable ; l~2 feet may be taken as a maximum, per- 

 haps, beyond which it will not be prudent to go, as a ship of this 

 class must be able to run close in shore. As a consequence of the 

 breadth, say 30 feet proportional to her length, our ship will have 

 a very flat floor. Her plating must be brought down far below the 

 water-line. As little armor will be carried above that level, there is 

 apparently no reason why the hull should not possess ample buoyancy 

 to support any reasonable weight which can be suspended from its 

 sides in this way. Masts and sails will be out of place. 



The .utility of this gunboat, for such she will be virtually, notwith- 

 standing her size, will absolutely primarily depend on great speed. 

 With such a moderate draught of water as 12 feet no single screw 

 would be suiiioient to confer this qualification; and for this reason, 

 and some other considerations connected with facility for nianoeuver- 

 ing, it becomes expedient that two propellers should be employed. 

 These propellers, then, will be driven by independent engines of 

 great power, direct acting, and capable of running at a very high 

 velocity. 



As the ship is not intended to proceed further out to sea than 50 

 or 60 miles, or to take any cruise which would occupy more than 

 three days at most, nearly all the space on the lower deck from one 

 end to the other will be available for engines, boilers, and coal ; anil 

 because 300 tons of this last will always be enough to take on board 

 at one time, an enormous amount of boiler room Avill be available. 

 The engines will be constructed to work expansively under ordinary 

 circumstances, with i or ^ boiler-power; when going into action the 

 funnels may be lowered, and blowers fitted in the engine-room will, 

 even then, with ease, burn 50 pounds of coal per square foot of 

 grate. 



As the hull to bo driven will be long and sharp, a spaed may, under 

 such conditions, be maintained the engines being worked at full 

 power, and the steam full stroke for four or live hours at a time, such 

 as no sea-going ship ever equalled. In moderate weather as much as 

 '21 knots may be realized. As the engines will only be called oa 

 t.) make such an extraordinary exertion at rare intervals, and as 

 plenty of time will always bs found to make repairs in port, where 

 su'^h ships will spend much of their time, there is little danger of a 

 bre ikdown, and the machinery can always ba kept in first-rate order. 



Stores, water, every consideration save armament, will give way to 

 the attainment of excessive speed for comparatively short periods, 

 a speed which it is impossible to realize under any other conditions, 

 a speed which will convert these coast defence ships into sea-eagles, 

 making their swoop where and when they please close to our shores ; 

 8 



