.S7A' WILLIAM SIEMENS, F.R.S. 407 



by one ring or tube, in which the strains were in the first instance 

 so arranged as to give each portion of the metal an equal strength 

 when the maximum powder-gas pressure was applied. He had 

 made a great many experiments with steel in the form of wire and 

 in the solid state. He had not, perhaps, explained as fully as he 

 ought to have done what he meant with regard to wire being no 

 stronger than solid metal. In speaking of steel wire he supposed 

 it to be annealed wire, that had not been subjected to any harden- 

 ing process ; but if the wire were cold-drawn, or oil-hardened, its 

 elastic range would certainly be greatly increased. Any kind of 

 steel, the mildest and the hardest, yielded in the same manner and 

 to the same extent by applying the same amount of weight per 

 square inch. The only difference between hard and strong and 

 weak steel was, that the weak or mild steel came sooner to the 

 limit of its elasticity. If it was desired to compare steel wire with 

 steel in bulk, the steel in bulk should be put into a similar aggre- 

 iratx- condition. Sir Joseph Whitworth could produce steel to 

 bear a strain of 80 tons or more in the bulk after he had oil- 

 hardened it ; and Dr. Siemens knew from experience that it was 

 exceedingly difficult to get steel wire, even when oil-hardened, 

 that could be depended upon to resist more than 80 tons per square 

 inch ; occasionally 100 tons, or even 110 tons, might be reached 

 in very thin wire, owing to great success in the mode of hardening. 

 In order to make a fair comparison, a metal in the form of wire 

 should be compared with metal in bulk subjected to analogous 

 processes, when it would be found that the absolute tensile strength 

 was nearly the same, whereas the solid steel had generally the 

 advantage of elongating to a greater extent than wire, before 

 rupture took place. 



