SIX WILLIAM SIEMENS, F.R.S. 173 



immediate vicinity of the hole, and did not extend to any 

 distance through the metal, which was in accordance with the 

 explanation he had suggested. 



The author had added an important item of information with 

 iv_ r ard to the staying of flat surfaces. The addition of the nuts 

 to the stays showed a remarkable increase of strength, and he 

 hoped that mode of staying would be generally adopted. It was 

 a question however whether for flat stay-plates this very mild 

 steel should be used ; it would probably be more advantageous to 

 use for flat surfaces steel containing perhaps 0*4 per cent, of 

 carbon ; they would then get a material of great stiffness as well 

 as great strength, and still of sufficient ductility. Steel with 

 about 0'4 per cent, of carbon would not indeed elongate 25 per 

 cent, before breaking, but it would elongate probably 12 per 

 cent. ; and in the case of a flat plate that ought to be sufficient. 



He might mention that lately he had witnessed two experiments 

 made with a view of bursting a steel boiler. These were made at 

 Swindon by Mr. Dean of the Great Western Railway ; and Mr. 

 Parker, the Chief Surveyor at Lloyd's for the boiler department, 

 was present at the second experiment. Both experiments failed, 

 i.e., they could not burst the boiler ; and he believed it was 

 impossible to burst a steel boiler. It might be expanded and the 

 joints racked to the extent of introducing an amount of leakage 

 that would prevent further accumulation of pressure ; but it 

 would never be burst. That condition of things was certainly a 

 satisfactory one. 



In the discussion of the Paper 



"ON A NEW REVERSING AND EXPANSIVE 

 VALVE-GEAR," by Mr. DAVID JOY, 



DR. C. W. SIEMENS * said that, listening to the very excellent 

 paper which had been brought before them, and to the observa- 



* Excerpt Minutes of Proceedings of the Institution of Mechanical Engineers 

 1880, pp. 444-445. 



