132 Cincinnati Society of Natural History. 



The penetrating effect of a projectile is equal to the energy per 

 inch of circumference in foot-tons, i.e.., the total energy divided by 

 the number of inches in the circumference of the projectile — 

 Wv2 



~" 2gX2TR2 



The energy of the projectile is met by the resistance required to 

 shenr a hole in the armor, which will coincide with the circumfer- 

 ence of the ]:)rojectile. 



In 1865 our largest guns were smooth-bore, muzzle-loaders, 20 

 feet 3 inches long, 20 inches caliber, and weighed 51 tons. 



Tlien came the long, tapering steel guns, built up of numerous 

 coils of steel, with breech plugs or "obturators," which are 

 hinged to the breech of the gun, or are arranged to rest on a sliding 

 table, to be moved by stean). 



The dimensions of the steel guns are as follows: 



23 feet 4 inches long, 8 inch caliber, 13 tons weight. 



28 " 5 " " 10 " 27 •' 



34 " I " " 12 " 47 " " 



45 " 5 " " 16 " 115 " 



60 " o " " 17^ " 150 " 



Dimensions, etc., of the iio ton ("Armstrong Gun") English 

 gun, breech-loader: Caliber, 16. 25 in.; lengtli, 43 feet ; length of 

 bore, 30 feet; weight of gun charge, 900 pouhds powder; weight 

 of projectile, 2,240 pounds; length of projectile, 4^^ feet; range, 

 10 miles, at high elevation, 13 miles; muzzle velocity, 2,128 feet 

 per second; energy, 56,520 foot-tons ; penetration, 33.8 inches in 

 wrought iron, will withstand a pressure of 30 tons to the square 

 inch. 



The big German gun, of Krupp, weighs 150 tons; the ])rojec- 

 tile, 3,300 pounds ; the length is 60 feet ; charge of powder, ^2 ton 

 range, io}4 m les.* 



At the Centennial Exposition is, a wooden model of the shell of 

 the Krupp gun, which is 6 feet high and i '2 ft^et ^n diameter, or 

 4^ feet circumference. 



Instead of tlie old-fashioned 12 inch and 13 inch mortars, we 

 now have along 12 inch howitzer, firing a bomb-shell, and with 

 seventy pounds of powder it has a range of six miles. Fired at an 

 angle of 75° the shell can be thrown to the height of three miles. 



-••'Length of ch'irge, 6 feet 4 inches, second half with a cylindrical space 

 or finegrained poArler; length of shell, 4 feet 7 inches; weight of charge^ 

 ,800 pounds; charge of shell, 200 pounds. 



