1879.] on the ' Thunderer' Gun Exylosion. 2*13 



60 that it would bo ignited all at once, the intensity would bo at a 

 maxinunn, in fact a detonation would take place. This is what well 

 may have hai)pened under the circumstances occurring hero; but even 

 in the absence of such additions to the ordinary force of the explosion, 

 you have but to look at the proportions of that part of the gun where 

 the 85-lb. charge was at the time of its explosion, to see that those 

 proportions could not withstand the pressure arising from even a com- 

 mon ignition of that weight of powder. Referring also to Diagram Ga, 

 the curve of pressures in the gun, you will see that the maximum 

 pressure which comes on this part of the gun in ordinary use is only 

 some 4 to 5 tons, instead of the 21 tons wliich would arise from the 

 ordinary explosion of 85 lbs. of pebble powder. 



Diagram 17 is intended as a rough representation of what took 

 place when the hinder charge was fired with the other charge in front. 



There is a further evidence that at the time the gun exploded the 

 Palliser shell was still in it, and that is that which is afforded by a 

 stud which was picked up in the turret. 



I have explained to you the difference between the modes of 

 making the holes in the common shells and in the Palliser shells. 

 The Pallisers are cored, the others are made with a cutter ; as a 

 result, studs when taken out indicate by their ajDpearance whether 

 they have been in a Palliser shell or in a common one. 



The stud which was picked up is much battered, but enough 

 remains to cause all those who see it and who are acquainted with the 

 subject to say it is a Palliser stud, and that it is so is now further 

 corroborated by the fact that even although some pieces have been 

 knocked away from the stud, its weight is still slightly in excess of 

 that of a similar and perfect stud from a common shell. 



Now it must be remembered that this stud could not have been 

 accidentally in the turret. In the first place, owing to the manner in 

 which the studs are fixed in the shells, it is practically impossible for 

 them to come out ; and in the next place, the gun is loaded from the 

 outside of the turret, and a shell is never inside the turret at all except 

 when it is in the bore of the gun. 



There is another circumstance wliich points to there having been 

 two charges of powder in the gun, and that is the tremendous recoil, 

 a recoil so violent as to drive the buffers through the wrought-iron 

 transom on which they were carried, and this, notwithstanding that 

 the hydraulic apparatus for absorbing the recoil was acting, and must 

 have been doing so with extra vigour, as will be readily understood 

 when one recollects the augmentation of pressure necessary to drive 

 water through orifices at a greatly increased rate. Let me say here, 

 in antici^mtion of any objection that may be urged against the 

 hydraulic apparatus, as being too delicate an iniijlemont for purposes 

 of warfare, that notwithstanding this explosion occurred within the 

 turret the hydraulic apjiaratus was uninjured, and we were able to uso 

 it for the purposes of our experiments. 



I hope I have now proved to you that double-loading would account 



