88 ANNUAL OF SCIENTIFIC DISCOVERY. 



which the small could do. Mr. Mallett then, at considerable length, ex- 

 plained the difficulties which he had encountered and overcome in the con- 

 . struction of the mortars he had completed, capable of firing the above shells, 

 and the capabilities of the latter. It was necessary that a mortar large 

 enough to project such a shell should be constructed in separate pieces, 

 because so large an instrument could not be forged without sustaining flaws 

 in the difficult process of cooling. In his researches and consideration of the 

 subject, he was greatly indebted to Dr. Harte for the able manner in which, 

 with his profound mathematical abilities, he had aided him. He had also 

 considered the general question of the application of wrought iron to artil- 

 lery, and came to a conclusion which would show the improvement as re- 

 gards the money part of the question. From a table before the Section on 

 the board, the value of guns of equal weight was mentioned, in bronze, 

 wrought or cast iron, and German steel. A gun of say one ton in cast iron 

 would cost 1 ; in bronze, 10 ; in steel, 2 ; and wrought iron but 15- 

 A gun of wrought iron would be but one fifth the weight of a bronze gun ? 

 and therefore about four fifths of its weight was uselessly put upon the horses 

 employed to draw it. Other elements, such as wear and tear, and cost of 

 transport also remained to be considered. Capt. Blakelcy observed, that 

 after the explanations of Mr. Mallett, it would be unnecessary to spend time 

 in advocating the utility of monster guns. The objection to them so often 

 mentioned was their unwieldiness, but those who had witnessed the applica- 

 tions of Mr. Armstrong of water-power would perceive that they could 

 easily be moved by that means. The difficulty of constructing large guns 

 on account of the greatly-increased strain to which they were subjected 

 was also an objection ; but it was shown that those difficulties could be 

 overcome. His (Capt. Blakeley's) plan of constructing large guns differed 

 very slightly from that of Mr. Mallett. The interior of the gun was made 

 of cast. iron, because of its small cost, and placed on it were rings of wrought 

 iron, at a white heat, hammered together. A nine-pounder constructed on 

 this principle had been tested at Woolwich, and 158 rounds were fired, the 

 gun being loaded to the muzzle, and those who conducted the. experiment 

 declared that it was the strongest gun they had ever witnessed. Mr. Fair- 

 bairn had never seen a more perfect piece of workmanship than Mr. Mallett's 

 very ingenious gun, and it only remained to prove, by actual experiment, 

 whether it would succeed. He was of opinion, after much consideration of 

 the subject, that cast iron of the best quality was the most suitable material 

 for the construction of guns. Mr. Ronnie attributed the circumstance that 

 the Russian guns were enabled to fire two or three thousand proof rounds to 

 the fact that they used superior metal in the construction of their cannon. 

 He was inclined to think that cast iron was better than wrought iron, 

 owing to the great difficulty in the forging of wrought iron. 



ON THE INTRODUCTION OF HEAVY ORDNANCE INTO THE UNITED 



STATES NAVY. 



The new steam-frigates recently added to the United States Navy have 

 been armed with the new ordnance introduced by Commander Dahlgren, 



