390 Mr. Mallet on the Physical Conditions 



ments, the whole Committee have the fullest confidence ; and, in this point, the result is 

 also corroborated by the fact of the large size of the bars, and that there is no evidence 

 that the iron had been piled. 



" Besides the experiments given in this Report, the Committee commenced a series of 

 others, on the effect produced in a mass of iron by long heating, without cooling — by 

 heating and cooling alternately — by subjecting the metal, for several weeks, to a constant 

 vibration, &c. ; but the Committee are not clearly of opinion that they can depart so far, 

 from the inquiry to which they were limited. 



" V. — Conclusion. — From the results of the whole investigation, the following facts are 

 derived : — 



1. The iron of which the gun was principally made was capable of being rendered 



of a good quality by sufficient working. 



2. In the state in which the iron was put into the gun, it was not in a sufficiently 



good condition for the purpose to which it was applied. 



3. As the metal existed in the gun, it was decidedly bad. 



4. As to the manufacture of the gun, the welding was imperfect. 



" These facts relate exclusively to the gun submitted to the examination of the Com- 

 mittee, and are derived from Immediate experiment and observation ; but, besides giving 

 these to the public, the Committee feel bound to express the opinion, that, in the present 

 state of the arts, the use of wrought-iron guns of large caliber, made on the same plan as 

 the gun now under examination, ought to be abandoned, for the following reasons : — 



1. The practical difficulty, if not impossibility, of welding such a large mass of 



iron, so as to insure a perfect soundness and uniformity throughout. 



2. The uncertainty that will always prevail in regard to imperfections in the weld- 



ing ; and — 



3. From the fact that iron decreases very much in strength from the long exposure 



to the intense heat necessary in making a gun of this size, without a possi- 

 bility, with the hammers at present in use in this country, of restoring the 

 fibre by hammering. At the same time, the Committee would not wish 

 to be understood as expressing any opinion whether the construction of a 

 safe wrought-iron gun, upon some other plan, is practicable or impracticable, 

 in the present state of the arts, inasmuch as this subject has not been referred 

 to them by the Department. 



" By order of the Committee, 



"William Hamilton, Actuary. 

 "Philadelphia, August 8, 1844." 



