involved in t/ie Construction of Artillery. 379 



the fractures had followed their planes of cleavage, as the " planes of weakness," or of least 

 resistance, in the mass. 



The change of colour in the metal at these places was due, I imagine, to its having 

 united with a certain amount of silicium, introduced with the sand in the welding process, 

 or perhaps by cementation only, in the prolonged heating. The gun was stated to have 

 been more or loss heated in the forging for about six n-eeks. That the fracture in this 

 instance was originated in the false weld, does not admit of doubt. It is by no means 

 certain, however, that, had this unsoundness not existed, this gun would have borne the 

 same proof as an ordinary cast-iron gun of the same dimensions and of tlic best quality ; 

 indeed, I will venture to state ray conviction that it would not. This would not have 

 been so, had a more suitable sort of wrought-iron been applied to the making its consti- 

 tuent bars in the first instance; the "over-worked" iron used, having been, no doubt, the 

 result of over-anxiety, on the part of the highly respectable manufacturers of the gun, to 

 insure its perfection, by using for it the most highly refined iron. 



The long false weld was perlectly undiscernible to the eye prior to proof, though, had 

 water pressure been applied as a preliminary test, it would probably have opened and 

 shown. 



The method of putting together the gun in longitudinal voussoirs prior to faggoting 

 was a capital mistake, though offering some specious advantages, in the operations of 

 welding, and possible to be carried out upon a smaller scale. 



The facts are worthy of notice, as indicating the absolute uncertainty that ever must 

 e.xist as to the trustworthiness of wrought-iron guns, forged in one great mass, although 

 executed without regard to cost, and by parties anxious faithfully to produce a result of 

 the highest excellence. Some of the evils incident to this gun might have been avoided 

 by greater experience and judgment ; but the main evil is inherent, and inseparable from 

 every huge forging, and most so where the weldings are most numerous. 



The following document, addressed to the American Government, is so instructive upon 

 all that relates to this subject, that I print it at length : — 



" Report on the Explosion of the Gun on hoard the United States Steam-Frigate, 'Princeton.' 



" The Committee on Science and the Arts, constituted by the Franklin Institute of the 

 State of Pennsylvania, for the promotion of the Mechanic Arts, to whom was referred, by 

 the Legislature, for investigation, the cause of the explosion of the gun onboard the steam- 

 frigate, ' Pi'inceton,' report: — 



" That they commenced their labours on the 5th of April last (1843), at a preliminary 

 meeting, on board the ' Princeton,' for the purpose of inspecting the gun in place, and for 

 arranging the order, &c., of the investigation. The deliberations of the Committee at this 



