1879.] on the ' Thunderer' Gun Explosion. 235 



the noise of tlio exj^losion is heard, the gunner No. 1 in charge of the 

 lever g, docs put it into this running-in i^osition. At first, and without 

 consideration, one is tempted to say this must be a wrong thing to do, 

 because the object at that time to be obtained by the aj)paratus is to 

 check the recoil, and therefore the putting the lever r/ in such a 

 position as (apparently) to cause a water pressure to aid the recoil 

 must be wrong. But reflection sliows this not to be the case ; the 

 ojiening tlirough which the water from the accumulator enters is so 

 small, that even when all resistance is removed, the water cannot flow 

 into the cylinder / with sufficient rapidity to fill the space between the 

 end d and the piston e, as that spacQ is enlarged by the rapid motion 

 of the piston when driven in by the recoil ; and I need hardly tell you 

 that if the water does not fill the space, the unfilled part will be in a 

 vacuous condition, and practically to as great an extent as if no water 

 were there at all. When any water is there, the vacuous space will 

 be less ; but less though it be, it will be equally vacuous, if I may use 

 such an expression, and therefore no pressure will be applied to the 

 piston e to drive it towards the left hand, and thus to assist the 

 recoil. 



Now, as the object of the crew working the gun is to do so with 

 rapidity, and as the necessary inward run of the gun, as I have already 

 told you, is not effected by the recoil alone, there is every reason why 

 the man in charge of the lever g should move it directly he hears 

 the explosion, because by doing so he does not, as I have pointed out 

 to you, aggravate the effect of the recoil, and he does make a connec- 

 tion with the water in the accumulator, so as to cause the pressure 

 from it to continue, without a break, the run in which had been com- 

 menced by the recoil ; whereas if this course of putting over the lever 

 immediately were not adopted, the man would be compelled to wait 

 until the motion from the recoil came to an end, and then the gun 

 would have to wait until the sjDace between the piston e and the 

 cylinder end d was filled up before the gun would re-start on its 

 inward run. 



I have already told you how the position of the slides as regards 

 elevation and depression may be altered ; but I need hardly say that 

 the inclination of the gun for aiming at each time of firing is not made 

 in this manner, but is effected by vibrating the gun on its trunnions 

 by aj^propriate apparatus ; and it is this apparatus which also dejn'esses 

 the muzzle of the gun into the position for loading, about which I shall 

 have to speak shortly : but previously I must say a few words as to the 

 general arrangement of the ' Thunderer.' 



Diagram 11 exhibits a plan view of the deck of the ' Thunderer.' 

 A is the fore turret, containing the two 38-ton guns, one of which 

 burst, and B is the after turret, containing two 35-ton guns ; and let 

 me mention that, as regards bore and thickness of metal, the 35-ton 

 guns are practically identical with the 38, but being loaded by hand 

 from within the turret they are of necessity some 3 feet shorter than 

 the 38-ton guns, which, as you will presently hear, are loaded 



11 2 



