40 



Popular Science Monthly 



90 feet long. Heavy as the mass is, 

 a huge lathe turns it around as 

 easily as a body turns a spool. 

 After the inside has been rifled 

 or scored to form an inside surface 

 that gives the shell a twist before 

 it leaves the muzzle and causes it 

 to fly straight, the lower or muzzle 

 end of the gun is made larger. 

 This may be accomplished in one 

 of two ways. Either additional 

 shorter steel tubes are placed over 

 the main inner tube, or the main 

 tube is wound with wire and 

 finished with an outer tube. The 

 wire-wound guns are usually the 

 heavier and are used on board ship. 



Why the Wire-Wound Gun Is 

 So Strong 



The gun bound with wire is 

 really stronger than the one built 

 of bands or rings of steel, one on 

 another; for the wire reinforces the 

 gun tube so that it will safely with- 

 stand the tremendous strain which 

 is constantly put on it when it is 

 fired — said to be as much as seven- 

 teen tons pressure on each square 

 inch. This means a pressure on 

 every little space inside the gun 

 as big as a domino of over 38,000 

 pounds. No wonder that a gun 



The upper portion of a blast furnace in which pig iron 

 is made — the first step in making steel. These men 

 are dumping iron ore, coke and limestone into the 

 large hopper. The materials are allowed to fall at 

 intervals into the inside of the furnace where the 

 intense blasts of hot air cause them to melt, mix and 

 fuse together until they are tapped out at the bottom 



This is a steel ingot. It is the large block of steel resulting from pouring the hot liquid steel into 

 a large mold and allowing it to cool. After it is cold the ingot is taken, in the manner here shown, 

 to the large forge shop for conversion into a big gun. This block weighs something over 111 tons 



