WILLIAM SIEMENS, F.R.S. 313 



In ihe discussion of the Paper 



"ON IRON AND STEEL FOR SHIP-BUILDING," 

 By MR. N. BARNABY, 



DR. SIEMENS * said, there can be no doubt that steel is a metal 

 which is worthy of the highest consideration of ship-builders, 

 engineers, boiler-makers, and all persons, in fact, engaged in 

 construction of that kind. One thing is necessary, namely, that 

 those who use that material should know what it is. We hear of 

 comparative results of steel and puddled iron as produced in one 

 furnace and another furnace ; and one would naturally come to 

 the conclusion that steel was a definite compound varying only as 

 regards quality. What is that compound may I ask ? Steel in 

 the form of a needle, an edge tool, or of a punch, is of a hardness 

 approaching that of the diamond ; steel in the form of a spring is 

 of an elasticity unequalled by any other metal, or any other sub- 

 stance in nature. Then, again, steel in the form of a milled plate 

 is, with few exceptions, the toughest material in existence, tougher 

 than copper or wrought iron. It can be moulded into almost any 

 shape in a cold condition. Therefore, we ought first to under- 

 stand what we mean by steel before we consider its merits or 

 demerits for structural purposes. You may say that the hardness 

 depends upon the proportion of carbon in the metal. Does it ? 

 I have lately experimented with steel containing four-tenths per 

 cent, of carbon. That steel, if treated in a certain way, would 

 make an excellent punching or cutting tool. If treated in another 

 way and annealed carefully, it is so tough that you could work it 

 into the form of your hat. Then, again, drawn into wire and 

 annealed in another way that is to say, heated in a certain way 

 and then put into oil it assumes a tensile strength of nearly 

 100 tons per square inch ; whereas, in the other form just before 

 mentioned, when annealed carefully its tensile strength would not 

 exceed 85 or 36 tons. Now, if the mere fact of after-treatment 



* Excerpt Transactions of the Institute of Naval Architects, Vol. XVI. 1875, 

 p. 140. 



