102 



REPORT 1855. 



explosion of powder in the chamber; that it is still a question, whether, with 

 our present means of forging large masses of iron, we may not obtain powerful 

 forged iron guns ; but so great is the difficulty of obtaining a sufficiently 

 large mass of iron sound in every part, so great is the expense arising from loss 

 of material by oxidation, and such is the tendency to basaltic crystallization 



Fig. 2. Fig. 3. 



Diagram to illustrate the effects of casting solid, Mr. Nasmyth's method of casting mortars with 

 the interior being weak and spongy. a malleable iron chamber. 



Vertical section. Vertical section. 



Horizontal section. 



Horizontal section. 



which the long-continued heating produces, that Mr. Nasmyth comes to the 

 conclusion, that powerful ordnance cannot be manufactured advantageously 



