402 THE SCIENTIFIC PAPERS OF 



the same ratio ; and this action between the two principal portions 

 composing the gun could only be obviated if the inner tube was 

 of such a material as to yield absolutely to the outside strain. 

 Therefore, it was not with a view of criticising, but rather with a 

 view of suggesting, that I ventured to make the observations I did. 

 I thank you very much for the kind attention you have given me 

 this evening. 



Tn llw, discussion of the Papers 



"ON IKON AS A MATERIAL FOR ARCHITECTURAL 

 CONSTRUCTION," by J. ALLANSON PICTON, F.S.A., and 



" ON MILD STEEL," by A. W. B. KENNEDY, M. Inst. C.E., 



DR. C. "W. SIEMENS, F.R.S., Hon. Associate,* said : I am sure 

 I cannot do less than congratulate you, Mr. President, and the 

 Institute of Architects upon the interesting and valuable papers 

 to which we have listened. Mr. Picton, in surveying the whole 

 question of the application of iron and steel to architecture, 

 appears to have taken such a broad and enlightened view of the 

 subject, that I hardly know what to add. Professor Kennedy 

 has dealt more particularly with steel, the latest development of 

 iron as it may be called, and with its preferential merits to iron ; 

 and as my name has been connected with one of the processes 

 now largely used for producing this material, I may be expected 

 to offer a few remarks chiefly with reference to the properties 

 of steel and its applicabilities for architectural purposes. Steel 

 is a material, which, as Professor Kennedy very correctly said, 

 has not been well defined. We call steel the material of which 

 watch-springs and cutting tools, needles, &c., are made, and we 

 all know it is very remarkable for its hardness, its great elasticity 

 or rather, I should say, its high limit of elasticity, and also for 

 its brittleness the moment that limit is exceeded. We call steel 



* Excerpt Transactions of the Boyal Institute of British Architects, 1879- 

 1880, pp. 173-176. 



