PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 555 



cnconiitor v>'itli Fort Fislior, and two of tlie eight burst under tlio most 

 rapid liring they have yet been subjected to. The navj^-cliarge for these 

 guns is thirty-five pounds of powder, with a shell of three hundred and 

 fiftj' pounds, or a shot of four hundred and fifty pounds, which is a very 

 small charge, and usually they are fired once in fifteen minutes. Tiie velo- 

 city of the shot is so low that the effect is not what was promised or 

 expected of them. Of the only two shots we know to have hit the sides of 

 an iron-clad, one struck the pilot-house of the Atlanta, and one struck the 

 Tennessee, but neither accomplished much. 



PARROTT GUNS. 



83. Twenty-three large Parrott guns burst on Morris Island in 1863, 

 under General Gilmore, yet tiiis alarming failure has not hindered tlie con- 

 tinuance of their supply. Before that time six had burst in the navy, 

 beside a great number that were disabled, and in 1864 about thirty-three 

 have burst in the navy, of which eighteen failed in Admiral Porter's fleet; 

 perhaps there were more, fov the admiral reported that alt the rifled guns 

 in the fleet liad burst. At the time of the encounter with the iron-ckid 

 Albermarle, it was reported that one hundred-pound Parrotts were useless 

 against ])lating with ten pounds of powder. Now it is proposed to reduce 

 the charge to eight pounds, which must vastly diminish their value. 



84. The Parrott gun embodies " initial tension " also under the band. 

 When fired rapidly the inner metal is expanded lengthwise and radially ; 

 when so strained a slight shock will break it. The rapid firing off Fort 

 Fisher was too much for them. 



85. On Mori is Island, tlie gtins were fired mostly at high elevations; 

 under such circumstances the pressure and temperature of the gases is 

 higher, and the time of the action of the force and heat is longer for each 

 discharge; consequently less rapid firing bursts the gun. 



86. The thirty-pounder that endured four thousand six hundred rounds 

 ■was a small gun, and was heated more nearly uniform throughout because 

 of the* thinness of the walls, and because of the long intervals between the 

 rounds, which was fifteen minutes. 



ARMSTRONG AND WHITWORTH GUNS. 



87. Built up guns, like the Armstrong or Whitworth guns, although 

 capable of enduring heavy charges, fail with rapid firing ; not always by 

 au explosive bursting, but by ruptures or enlargements that disable the 

 guns. More than l,4tJ0 Armstrong guns or parts were returned for repairs 

 up to 1862, at which time but about 2,000 guns of this kind had been 

 fabricated. 



AMES GUNS. 



88. Guns forged solid, like the two guns on the United States steamer 

 Princeton, and the Ericsson thirteen-inch gun burst because it is impossi- 

 ble to attain uniformity of fabrication, and because of the unequal expan- 

 sion. The Ames gun, although somewhat more uniform, cannot be abso- 

 lutely so, and will either burst or enlarge in the bore. 



89. Of wrought-iron guns that at present are most conspicuous is that 

 of Mr. Ames. He claims three qualities for his guns. First, tha^ it is 

 made of a superior, strong and tough, or ductile iron, the Salisbury* 



