.S7A 1 \\-ll.I.IA.M Xll'.MENS, F.R.S. 393 



The interest at present manifested in the substitution of steel 

 for iron for engineering purposes has induced the author to bring 

 this paper before the Institution without waiting for practical con- 

 liniKitiou upon an extended scale of the construction involved : the 

 question is one rather of mechanical detail than of principle, the 

 object being to treat material in such a way as to develop its 

 maximum of resisting power when applied to the construction of 

 vessels to resist high internal pressure. 



DR. SIEMENS said he should be glad to hear the opinion of prac- 

 tical engineers as to the probable advantage or disadvantage of 

 the mode of construction described in the paper ; but certainly the 

 vessel constructed on this principle had so far given very satisfac- 

 tory results.; and he believed that vessels, such as air-vessels, could 

 be constructed with rings in the manner described, both cheaply 

 and with great safety. It would be observed that each ring had 

 not to be turned throughout the entire width of the flanges, but 

 had simply a groove turned in it at each end ; and these grooves 

 were all of the same diameter and section, so that when the copper 

 packing-rings were put into position in the grooves the whole 

 vessel was built up and the bolts were tightened, and there was no 

 further labour expended upon it. 



The copper packing-rings were from \ inch to inch thick, 

 according to the diameter of the vessel for which they were used. 



DR. SIEMENS, in replying upon the discussion, said the plan of 

 the compound cylinder, which had been described by Mr. Weems, 

 was not at all the mode of construction that he considered the 

 best adapted for vessels intended to withstand the high pressures 

 contemplated in the paper. 



"With regard to Mr. Tvveddell's suggestion that the joints shown 

 in the drawing should be made with leather or hemp instead of 

 with copper rings, he feared those soft materials would not stand 

 very high pressure. Where there was a pressure of 1,000 or 

 i',oiMi lb. per square inch he had found india-rubber, for instance, 

 always to give way. Moreover to make a joint with any of those 

 materials, there would have had to be a sufficiently broad face. 

 The ends of the rings or cylinders would have had to be faced 

 completely, and a considerable breadth of face given to them. It 



