.s/A- \V1I.UAM SIEMENS, F.R.S. 43 1 



case of weakness of the metal, under so very moderate a pressure 

 Ibs. per square inch ; but that from one cause or another 

 tin- metal had been cracked and broken previous to testing. He 

 rniild not speak as to the cause of the metal being in that condi- 

 tion ; and he would only say at present that mild steel, properly 

 made and properly put together, would not burst under any 

 ire whatever. If a boiler made of mild steel were subjected 

 to an increasing pressure, it would be found impossible to burst it. 

 And it was natural that this should be so. A material that would 

 stretch 30 per cent, before rupture, would naturally give way first 

 at the weakest sections, namely those through the rivet-holes ; the 

 round rivet-holes would become oblong, until sufficient water or 

 steam leaked out to balance the amount of water pumped in or 

 steam generated. That was not a mere hypothesis of his. He 

 had witnessed some experiments made by Mr. Dean, the locomo- 

 tive superintendent of the Great Western Railway, in the presence 

 >f Mr. Parker, the chief surveyor of Lloyd's, and described in a 

 paper by Mr. Parker before the Institution of Naval Architects * 

 in 1878. The leakage began at 560 Ibs., and the highest pressure 

 reached was 800 Ibs. Messrs. Easton and Anderson had also tried 

 a boiler made of mild steel ; and, in order to increase the severity 

 of the test, between each trial they put the boiler into a furnace, 

 made it red hot, and then took it out again, caulked it where it 

 appeared necessary to close the seams, and then again subjected it 

 to a pressure of several hundred pounds per square inch. He 

 believed that Mr. Greig had also made similar experiments. It 

 might therefore almost be taken as an axiom that a steel boiler 

 could not be burst ; it might be made leaky, but that was all. 



With regard, then, to the great question as to whether mild 

 steel was a reliable material or not, he would answer most un- 

 hesitatingly that it was the most reliable material they knew of ; 

 they might punch, shear, bend it, or do what they liked with it, 

 but they would not in any way destroy its tenacity. By way of 

 practical proof he might mention one other fact. The steamers 

 "Iris" and "Mercury" had been constructed of mild steel about 

 three years ago for the Admiralty : not only the shell-plates of the 

 vessels, but the angles and the whole of the boilers were all con- 



* See Transactions of the Institution of Naval Architects, 1878, p. 178. 



