MEMOIR OF DANIEL TREA DWELL. 4 .V, 



intended. These bars are then placed in a long narrow, reverberatorv furnac and i ised to a 

 bright red heat. When ready for coiling, one end is drawn o.n and fixed to a revolving 

 drel, which pulls the bar out and winds it into a coil, like a rope round a Bpstan : it is tl 



man- 



ual a 1111 



heated and welded under a steam hammer: on cooling, it is bored and turn.. I to the proper 

 dimensions." 



The Krupp gun also has a steel tube, but much thicker than the Armstrong ran 

 and m this respect still more nearly approaching the Tread well pattern, with env- 

 iron body; over a considerable portion of the chase, hoops of cast Bte< I are shrunk, 

 the shrinkage being so adjusted that the successive layers of hoops shall support the 

 body of the gun. The number of the hoops depends upon the size of the gun. 

 usually greater than that of the English coils. They are secured in their places 

 on the body by a number of splines, which prevent movement. The details of the 

 manufacture of the Krupp guns have not been made public. It is not known 

 that the Tread well method of hammer hardening the hoops to n tore their elas- 

 ticity after heating is practised by Krupp; nor is it known that he used Mr. 

 Treadwell's method of employing heated oil to determine the limit of tempera- 

 ture to which they should be heated when they are placed in position on the body 

 of the gun. 



Captain T. A. Blakely made a tube of cast iron resembling a gun, and over it 

 forced with a hydraulic press one or more tubes accurately turned on the inside, of 

 wrought iron. A gun thus made with hoops scarf-welded successfully r< ted more 

 than ordinary charges. Subsequently, after 1854, he adopted Treadwell's method of 

 heating the ring's and shrinking them on the body. 



The Russian government has a foundry for guns of large calibre. These guns 

 have a body of steel upon which are shrunk hoops also of steel; a twelve-inch gun 

 weighing 89,296 pounds has forty-seven hoops. 



The Whitworth gun is in its essentials made after the method of those just de- 

 scribed. As already stated, he prefers, like Treadwell, hydraulic pressure to the 



steam hammer for his forgings. 



Comparing these cannon with those made by Treadwell for our own Government 

 in 1842, and those of his specification in 1854, we cannot but be struck with their 

 close resemblance, both in the principles and method of construction. They are 

 in fact substantially the same, — the same principles and methods upon which the 



d most enduring sruns are now made. The making of the hoops by wind- 



n ~ „,».„. mu^i; v i i««i.w n _, 



ing the bar like a rope on a capstan, instead of a ribbon on a block, is not material as 

 to strength. Indeed, as we have already said of the guns of 1842, we may now say 

 of the guns of 1854 : if all knowledge of Armstrong's methods were lost, they could 



