﻿16 ON CONSTRUCTING CANNON OF GREAT CALIBER. 



Atmospheres. Atmospheres. 



Hooped cannon for 14-mch shot will bear . . . 4,266 ; required 2,133 100 : 200 



Cast-iron gun, 14-inch shot, will bear . . . 1,333 ; " 2,133 100 : 62 



Cast-iron 32-pounder cannon, 6^ inches thick, will bear . 1,333; " 920 100:142 



Hooped cannon 30 in. diam., 3,670 lb. shot,will bear . 4,266 ; " 4,266 100 : 100 



By this it appears that a common cast-iron 32-poiinder, having but 42 per cent 

 more strength than is required, is less reliable than a hooped gun of 14 inches. It 

 will be recollected that the numbers given above in the second column, as show- 

 ing the requii-ed strength, represent the utmost force ever exerted by a charge intended 

 to produce a velocity of 1,600 feet a second. 



In this paper, my principal object has been to show a mode of construction by 

 which, with our present materials and knowledge, it will be perfectly practicable 

 to make guns of great size capable of standing the requirements of the service. It 

 follows almost of course, that the same form of construction must be the best possible 

 for guns of smaller caliber, and that by adopting it, not only will the use of guns 

 of enormous size be rendered practicable, but, if applied to cannon of smaller size, their 

 bursting will be rendered almost impossible. If it be necessary to use the word cost 

 in connection with the object to be attained, I knoiv that when the manufacture is 

 mastered, with a good machine-shop, the difference between the last of these and 

 common cast-iron guns wUl be altogether insignificant to the nation. 



I abstain from opening the subject of different forms of bore and of shot, although 

 I believe that in the end some cylindrico-conical form, lightened with cavities in the 

 rear portion, and perhaps vnih some form of spiral grooves to produce rotation from 

 the air, wUl be substituted for the solid spheres now used. 



I shall likewise forbear all description of apparatus for restraining recoil, by friction, 

 although it will be necessary to resort to such means for the fuU development of the 

 advantages of the form of cannon herein pointed out. 



I should, however, leave the subject of this paper but very imperfectly treated, if I 

 neglected to mention one most important effect of the force of the explosion, which 

 is not indicated a imori by any theoiy, and which is so inconstant and uncertain in 

 amount, that it can be appreciated only by a careful observation of its practical effects 

 upon the gun, but which, unless guarded against, must essentially disturb the con- 

 clusions which I have herein deduced. I allude to what is knoAvoi to artillerists as 

 the lodgment or indentation of the ball. This first shot\'S itself at the point immedi- 

 ately under the baU, where it rests at the moment of the discharge. It is best ob- 

 served in a soft bronze or wrought-iron gun, and from the first instant of its appear- 

 ance, as a slight impression of the under surface of the baU, it goes on increasing at 



