September i8, 1890] 



NA TURE 



50^ 



the use of servo-motor valves, so that the handwheel is small 

 and requires but little power to move it. It only remains to 

 describe as shortly as possible the system of mounting the guns 

 on the turntable. The guns are trunnionless, to allow them to 

 be as close together as possible, with the view of reducing to 

 the smallest possible size the diameter of the turntables. The 

 carriages are cradles of steel grooved to correspond with rings 

 turned on the guns, and with straps by which the guns are 

 secured to the cradles. The carriages are mounted without 

 rollers or wheels on slides formed of steel beams of great 

 strength, pivoted at their front ends and supported on hydraulic 

 presses, by which they are bodily raised or lowered to give the 

 guns elevation or depression. In the case of the turret this 

 system gives the smallest possible port. The loading of the gun 

 is effected while the gun is at extreme elevation, a position 

 which is easily determined by dropping the slide on to fixed 

 stops, and which gives the best protection for the breech mech- 

 anism, for the hoist and rammers. The operations of unlocking 

 the breech-block, withdrawing it, traversing it, inserting a load- 

 ing tray, and, after completing the loading, performing the same 

 operations in reverse order, are all done by hydraulic power, 

 and the fittings are so devised that, unless the gun is properly 

 locked and run out, it cannot be fired. 



In certain foreign vessels provided with the hydraulic breech 

 mechanism, a valve has been arranged which makes in their 

 proper order, and in that order only, the eight or ten movements 

 necessary to open and close the breech of the gun, but this 

 system has not been adopted in our own navy. 



The sights are carried on the top of the turntable, or, in the 

 case of a turret, on the turret roof, and are worked automatically 

 by an arc attached to the gun slide, gearing into cog-wheels, 

 with shafting reaching to each sighting position. 



The system of recoil press adopted on all these ships is that 

 which lends itself most readily to employment also as a running- 

 in-and-out press. It consists of a simple cylinder carried in the 

 middle of the slide, having working in it a ram with piston, 

 attached at the front end to the carriage. Spring-loaded valves 

 are placed in the recoil ram piston and at the end of the cylin- 

 der, and by these the water escapes when the gun recoils. The 

 water which passes through the cylinder valves runs to the 

 exhaust-pipe, while that which passes through the piston valve 

 remains in the front of the cylinder, and prevents the gun 

 charging out again. When the recoil press is used to run the 

 gun in and out, these valves are inoperative, as they are loaded 

 much above the working pressure in the hydraulic mains. The 

 high pressure of recoil does not enter the hydraulic mains, as 

 the supply to the rear of the press, where alone the high pressure 

 of recoil exists, is made backwards and forwards, through a valve 

 which shuts itself automatically when not in use. 



Before leaving the working by power of heavy guns, there is 

 one example of mounting a pair of guns en barbette which, 

 although it has many points in common with the system I have 

 just described, has also some points of difference, which it may 

 be worth while to note. 



Objections have sometimes been urged to the fixed loading 

 station on the ground that it is necessary to bring the guns to it 

 and lock them there until sponged and loaded, thereby involv- 

 ing, not only a loss of time, but, under certain conditions, 

 exposing them more to the enemy's fire. 



In ships of the Re Uviberto type, what is termed an all-round 

 loading is obtained by bringing up the ammunition through a 

 central hoist to the deck below the turntable. From this cen- 

 tral hoist it is transferred to two other hoists, which are carried 

 on the turntable behind the guns. The transfer is made by 

 hand for the powder, and by sliding down a tray for the pro- 

 jectile, this work being performed by men on the deck below 

 the turntable. The hydraulic rammers are fixed to the turn- 

 table, and are very much shortened by being made w ith more 

 rams. In spite of this arrangement, however, the hoists are 

 rather cramped, and the breech mechanism has to be made to 

 pass from behind the gun, so as to permit the gun to recoil, and 

 the gun is rather further forward than usual when run out. 



With these reservations, however, the system has advantages : 

 the reduction in the armour required to protect the turntable 

 and its machinery is considerable, and the redoubt being round 

 instead of pear-shaped, presents a smaller and stronger surface 

 to the enemy when broadside on, 



I very much doubt, however, whether with this system there 

 can be any advantage in rapidity of fire. Training to the load- 



NO. 1090, VOL. 42] 



ing station is in our navy very quickly done, and the turntable 

 is rotated while the guns are being run in or out. 



It is hardly necessary to say that hydraulic machinery for guns 

 was worked out by my friend and late partner Mr. George 

 Rendel, and up to the end of 1881 all details connected there- 

 with were made under his management. 



I ought perhaps to give you some idea of the rate at which 

 these heavy guns worked by power can be fired. 



In the case of the Benboiv, with the iio-ton gun the time 

 from " load " to "ready" was i\ minutes. In the firing trials 

 of the Trafalgar four rounds were fired from one of her 68-ton 

 guns in 9 minutes 5 seconds. In the Colossus, when under com- 

 mand of Captain Cyprian Bridge, the average from one round 

 to another was I minute 45 seconds, and on one occasion, 

 steaming at 8 knots per hour past a target at a distance of 1500 

 yards, she fired four rounds in six minutes, striking the target 

 three times. 



Of the mountings which are worked solely by manual power, 

 the whole range for naval service is covered by the carriages of 

 the type designed by Mr. Vavasseur. No single description can 

 be made to cover all the varieties of these mountings which have 

 been worked out to meet the diverse conditions which have 

 arisen in the re-arming of old ships, and the fitting out of new 

 vessels on modern and novel designs. The very general adop- 

 tion of breech-loading ordnance brought with it the necessity for 

 a mounting which would give easier access to the breech of the 

 gun than was obtained with the long low gun-slide employed 

 with the muzzle-loading guns. The main features of the type, 

 therefore, are : a high slide, very short, so as not to project 

 beyond the breech of the gun, a short low carriage carrying on 

 either side the recoil presses, and a shield to afford protection 

 both to the carriage and the gun crew. 



The increased importance of rapid-fire guns has led in later 

 carriages to a strong armour plate being built into the mounting 

 as part of its structure, and to this must be added the shield 

 above mentioned, so that the total protective thickness of plate 

 is very considerable. 



By means of a worm wheel sliding on a keyed shaft the move- 

 ment of the gun for elevation or depression can be made up ta 

 the instant of firing — a decided and very important advance on 

 the older methods. 



The arrangement of the recoil-cylinders is peculiar. They 

 are fitted with a pair of pistons with rotating valves, so adjusted 

 as to be open when the gun is in the firing position, and to be 

 gradually closed during recoil by studs running along rifled 

 grooves in the cylinders ; by this ingenious contrivance the area 

 of the ports of the valves is increased and then decreased in 

 proportion to the variation of the velocity of recoil, so that the 

 liquid passes from one side of the piston to the other at as nearly 

 as possible a constant velocity and under a constant pressure. 

 The velocity of the flow through the ports, and therefore the 

 pressure of the liquid, varies with the energy of the recoil of 

 the gun, so that the length of the recoil is with all charges 

 practically the same. 



Even a blank charge produces nearly full recoil, and on one 

 occasion caused one of these mountings to be reported as un- 

 serviceable, and unfit to fire a shotted round. Constant length 

 of recoil has the advantage over constant pressure in the recoil- 

 presses that, in the event of an unusually heavy recoil, a higher 

 pressure in the recoil-press would in the former case be the only 

 result, and would do no harm, as the pressure would still be 

 much below the test-pressure ; but in the latter case there would 

 be an increased length of recoil, and, unless considerable margin 

 were allowed, a possible destruction of the slide. 



Most frequently the Vavasseur. mountings are made with 

 central pivots, and there is then little tendency for the move- 

 ments of the vessel to affect the mounting, and as the weight is 

 borne upon a ring of live rollers the greatest ease of training is 

 obtained. 



In the larger sizes the centre pivot is increased in size, and 

 made hollow so as to provide for the passage through the centres 

 of a powder hoist, which, after rising high enough, curves to 

 the rear under the gun and delivers its charge at the point where 

 it can most conveniently be drawn out for insertion in the gun. 

 In this case a foot plate is also provided as a rear attachment to 

 the slide, and from this the crew work the gun. This foot plate 

 is provided with boxes for eight or ten projectiles, which are 

 therefore ready for use at any moment and in any position of 

 training. These mountings are fitted in the belted cruisers of 



