PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 431 



effect of heat discovered by myself. In this gun I provide strength to 

 resist the pressure of the powder, while I compensate for the effects of heat, 

 by superior elasticity, not only for the unequal expansion in the direction 

 of the diameter, but of length also. The gun is to be cast so near to the 

 required dimensions as to need no turning outside, thus preserving the 

 most enduring surface to the casting, and allowing it to compensate by in- 

 creased elasticity effectively for unequal heat in its inner and outer por- ^ 

 tions when made of one metal, as homogeneous cast iron. * 



The figures are a longitudinal section and a cross section of a gun con- 

 structed according to this invention. The passages are cast with cores to 

 leave webs in the doubly curved form represented. .The cores between the 

 webs, as also a core forming the bore, may be cooled by tubes containing 



water or other cooling agent, in the manner 

 patented by Captain Rodman, if preferred. 

 When the gun is fired, the heat communi- 

 cated to the interior surface expands the 

 '^ central portions of the casting. The open 

 • j condition of the iron iutermediate between 

 "^ the inner portion b and the exterior portion 

 b^ of the thick part or re-enforce of the gun, 

 allows this portion of the structure to yield 

 __ by its elasticity, both laterally and longitudi- 



nally, far more than when the gun is cast solid; so that the strain, whether 

 purely mechanical, i. e., due to the expansive force of gases, or due to the 

 heat of the interior, or, as will generally be the case, due partly to both, is 

 allowed for, first, the pressure by the strength of the re-enforce; second, the 

 expansion due to' heat, by the elasticity of the webs. The re-enforce being 

 cast of a somewhat greater thickness than other parts of the gun, will cool 

 last, and shrink to the required pressure against the webs, and through 

 them upon the inner metal. I can furnish these guns for five cents per 

 pound, there being no machine labor necessary upon them except drilling 

 the vent. I propose to cast the bore so near the proper size as not to re- 

 quire boring, and thus leave about the bore the most enduring surface. 

 The gun, too, being cooled from so much surface, will be of a more uniform 

 structure than has been before attained. 



I am a manufacturer, and whatever facility of adaptation I may exhibit, 

 is directly devoted to arranging plans for the purpose of making proposals 

 for the manufacture of the work designed in a practical manner, with a 

 view to that end only. My designs are the result of long study and close 

 application, assisted by a long practical experience in constructing 

 machinery and working metals. Whenever exhibited, these plans have 

 received a hearty approval from practical men. 



I have specified three general plans for the fabrication of large guns, 

 adapted to the various requirements of service. The spherical gun and 

 turret will answer as well for an iron-clad ship as a ram, although the 

 weight of the gun and the thickness of the turret are greater than those 

 heretofore proposed; the smaller diameter of the turret enables me to con- 

 struct it to have no greater whole weight than the Ericsson turret with 

 its guns; and when so constructed, it is a smaller object to be aimed at 



