222 Mr. F. J. Bramivell [June 13, 



honour me with their presence to-night are in the haLit of reading 

 such documents, or if they are, that they find them, in the absence of 

 models and of familiar explanation, readily intelligible. Bearing all 

 these considerations in mind, it appeared to me that a plain, un- 

 technical account of the investigation into the causes of the explosion 

 by one who took part in it from first to last, more especially if that 

 account were aided by diagrams and models, would not be uninteresting 

 to the members of the Royal Institution, and might not be without 

 its use in assisting to dissipate any feeling of doubt as to the safety 

 of our artillery which still lingered in the minds of some who knew 

 that a gun had exploded on board the ' Thunderer,' but who did not 

 know under what circumstances that explosion had occurred. 



Let me here say, although I think it barely necessary to do so, 

 that having been placed by the Admiralty in the position of Assessor 

 to the Committee which made the investigation, I should never have 

 thought for one moment (notwithstanding that our report was in the 

 hands of the public) of giving this lecture unless I had ascertained 

 that my doing so would meet with the full approval, as I am happy to 

 say it does, of the authorities of the Admiralty. 



I will now ask you to direct your attention to Diagram 1, 

 representing a longitudinal section, of the 38-ton gun which ex- 

 ploded. This gun you will see was composed of six pieces, namely, 

 the steel tube 12 inches in bore, and 16 feet 6 inches long internally, 

 upon which at the rear end is shrunk the wrought-iron coiled breech 

 piece ; the 1 B coil shrunk on to the tube in advance of the breech 

 piece; the B tube shrunk on to the steel tube in front of all, and 

 forming the chase or muzzle of the gun ; the C coil shrunk outside the 

 breech piece ; and the cascable screw in rear of all. The trunnions 

 by which the gun is supported on its carriage are forged in one with 

 the C coil. It will be observed that the ends of the different parts 

 overlap, and that at these overlajDping places there are appropriate 

 recesses, and projections to hook into those recesses, by which end way 

 connection is made among the various parts. Similarly, there are 

 certain projections on the exterior of the steel tube itself, which 

 prevent its endway motion. The tube is made from a solid steel 

 forged ingot, which is bored out to nearly the desired size, and after 

 having been toughened in oil (and about this toughening I shall have 

 something to say presently), has shrunk upon it the breech piece and 

 1 B coil and the B tube in succession. 



You will observe I frequently use the word " coil " when speaking 

 of the envelopes by which the tube is surrounded. They have this 

 name because they are made by winding bars of wrought iron of a 

 suitable transverse section round and round until they are made into 

 gigantic ringlets, ringlets very closely twisted, as you will see on 

 reference to Diagram 2. This represents a coil lying on its side ; it is 

 turned up on end and placed in a furnace to bo heated. The doorway 

 of this furnace, I may say in passing, is large enough to be traversed 

 by a full-sized coach. Here the heating is continued until the whole 



