PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 559 



this point the case is similar to that of a solid gun; beyond a pressure 

 equal to that of the powder, the ribs may yield to the pressure by heat 

 without straining the reinforce as much as it would be strained iu a 

 solid gun. 



106. But the barrel will not be heated as much as the corresponding 

 part of a solid gun, because it is exposed to the air on both sides, and pre- 

 sents a large radiating surface. Besides, the longitudinal expansion of 

 the barrel is the source of the greatest strain, and this, in the Wiard gun, 

 is provided for by the longitudinal corrugation of the ribs. 



107. The largest diameter of the reinforce is not a source of comparative 

 weakness. 



lOS. On the whole, it is probable that the barrel and ribs of Mr. Wiard's 

 gun can be cast without serious strains; that the reinforce can be shrunk 

 upon them with some degree of tension; that the strongest iron can be 

 used; and that the guns will not be seriously strained by haat. The fail- 

 ure of the first guns, if they should fail, ought to be attributed to the 

 improper carrj-ing out of the principles; for the present knowledge on the 

 subject of cast iron, however imperfect it may be, define these principles 

 with mucli clearness." 



109. The experience I have attained in the efforts to produce these large 

 guns gives me confidence now to state that I can make cast iron guns that 

 will not enlarge in the bore except as they arc worn out by long con- 

 tinued use, and that cannot be burst either by heavy charges or rapid firing. 

 And I can make or re-make such guns from old guns or from the fragments 

 of old ones, thus reducing the cost materially, while the efficiency is much 

 increased. 



110. The Dahlgren gun, of eight tons weight, requires sixteen tons, or 

 more, of iron to produce it, because more than one-half of the iron is wasted 

 by being cut away into chips of little value. 



111. It is proved by the preceding argument that Hodman or Dahlgren 

 cast iron guns can not be made of the strongest iron, consequently such 

 guns can not be made from fragments of bursted or rejected guns (for iron 

 is improved by re- melting.) Upon my system the strongest iron will make 

 the strongest and best gun. 



112. Upon my system the walls may be made equally strong with any 

 other by thickness; I can have the proper initial tension upon it to restrain 

 the pressure of the powder, and no other detrimental strain, which is not 

 possible in any other gun ever proposed ; while I provide the necessaiy 

 elasticity both longitudinally and radially to prevent the unequal expan- 

 sion from the heat of firing. In fact, I am confident I have discovered the 

 true and only system upon which guns can be made to endure the strains 

 of actual service, and I charge the Ordnance department with having prac- 

 ticed a studied system of oppression to prevent me succeeding in getting 

 my guns introduced, resulting in incalculable loss of money, life and pres- 

 tige to the government under which they occupy sinecure positions. 



113. I append hereto an extract from a letter from Ed. N.Dickenson, 

 Esq., of New York, and take the liberty to state that I can procure such or 

 stronger letters corroborative of the theories and statements affecting the 



