involved in (he Construction 0/ Artillery. 385 



does afford, to an experienced eye, an indication of the quality of the iron, and that the 

 same appearance offers a ready method of determining the homogeneity of the structure 

 of a large mass. 



" The next object of examination to be described v/as the surface of the original frac- 

 ture of the large fragment of the breech. This exhibited, in several places, traces of the 

 original bars of which the gun was constructed; also spots indicating a want of perfect 

 continuity in the metal, — which was the more evident, as these were, in some cases, 

 covered with a brittle scale of the oxide of iron, of the thickness of a sheet of drawing- 

 paper. The position and relative size of one of these spots is shown at a, in Fig. 1. It 

 is between 9 and 10 inches long, and, in the broadest part, 3 inches wide; it approaches, 

 at its nearest part, to within three-fourths of an inch of the chamber, and may have 

 extended into it in another plane oblique to that of the general fracture. Within this spot 

 was observed what, at first, appeared to he an imbedded lump of stone ; it was probably, 

 however, a mere scale of slag, since it was lost sight of in the subsequent operation of cut- 

 ting the iron. The Committee think it probable that, from the direction in which the 

 pieces must have been blown from the gun, and other circumstances, the rupture com- 

 menced near this spot, and that it was the approximate cause of the rupture taking place 

 in the plane exhibited, rather than in any other. 



" Besides the spots indicating a want of continuity in the metal in the plane of the 

 fracture, the edges of many others, in different planes, were observed ; also a wide solution 

 of continuity was shown throughout a cylindrical surface, concentric with the bore, and 

 extending, in one place at least, entirely around the fragment. This was evident from the 

 fact, that oil, poured in at the upper side, came out at a, after passing through a distance, 

 within the fragment, of about 3 feet. Another opening, in the prolongation of the cylin- 

 drical surface, is sliown at c. The sides of this were separated to a distance of a quarter 

 of an inch, and, by inspecting these, it was evident that they had never been welded: into 

 this opening a wire was thrust, to the depth of 10 inches. From the end of the same 

 opening, a crack extends into the bore of the gun, as is shown in the drawing. At e is 

 shown the section of a small cavity of a triangular form, the longer side of which was 

 about an inch, and the shorter half of that length, which has the appearance of having 

 never been filled up. The large solutions of continuity concentric with the bore were, in 

 all probability, at the place where the large masses — described in the answers of Messrs. 

 Ward and Co. — commenced to be welded on to the longitudinal shaft. 



"IV. — Ejcperiments relative to ilie Quality of the Material of the Oun. — In reference to 

 the experiments instituted for the purpose of testing the strength of the iron, it is impor- 

 tant, in the first place, to refer to the fact, that the pieces of iron were all cut from the 

 large fragment of the breech, and, therefore, from the immediate part of the gun where 

 the fracture occurred. The bar sent to Boston, to be experimented on by a member of the 



