SIR WILLIAM SIEMENS, F.R.S. 75 



the steam, varying of course with the degree to which the steam 

 was worked expansively. The circumstance that this amount of 

 heat was got rid of during the expansion of the steam in the 

 cylinder went far to account for the statement given in the paper, 

 that the quantity of injection water required to condense the steam 

 was found to be proportionate to the total weight of steam, or of 

 water evaporated, whether the steam were superheated or not : for 

 the heat added to the steam by superheating had probably been 

 hardly sufficient to replace the loss arising from expansion and 

 from the cooling by conduction and radiation from the metal 

 of the cylinder. He believed that by superheating the steam 

 judiciously a saving of from 15 to even 20 per cent, of fuel might 

 be effected, even upon a properly constructed engine ; but he was 

 equally satisfied that superheated steam must eventually give way 

 to regenerated steam, by which alone the full equivalent of motive 

 power could be obtained from heat, diminished only by the un- 

 avoidable losses from radiation, &c. 



In the use of high temperatures there was much difficulty in 

 getting the joints to stand steam-tight, which he had experienced 

 in superheating steam in his regenerative steam-engine ; and after 

 the failure of various cements and copper rings, he had succeeded 

 in making a joint that stood even a red heat and remained quite 

 steam-tight. The cement he used was composed of red lead and 

 oil mixed with as much dust of cast iron as could be worked into 

 it. He showed a specimen of the joint fresh made, and one that 

 had been exposed to a red heat in which the cement had become 

 nearly as hard as iron itself. 



