438 THE SCIENTIFIC PAPERS OF 



sidcrations involved which would have led beyond the usual range 

 of the discussions. He had, however, mentioned two processes 

 now largely used : the Bessemer process, which, by the great 

 revolutions it had effected not only in the manufacture of iron 

 and steel, but in the engineering of the world, was too well known 

 to require any further comment ; and the process with which 

 Dr. Siemens's name was connected, which, although much less 

 used, had been in existence nearly as long as the Bessemer process ; 

 and which, although it had been for many years confined to com- 

 paratively few works, had lately, owing to some particular advan- 

 tages it possessed under certain circumstances, attained a con- 

 siderable extension. Setting aside the question of process, the 

 paper dealt very ably with the modes by which the ingot metal 

 should be treated in order to convert it into such forms as were 

 required. The author advocated economy in the construction of 

 the steam-engine, a subject which Dr. Siemens was glad to see 

 had been taken up at last seriously by the makers of that class of 

 machinery. At the time when the puddling furnace and the re- 

 heating furnace sent up flames of living fire into the air, the 

 question of economy in the engine was really a superfluous one ; 

 there was so much steam produced in using only a portion of 

 the heat that would otherwise have been entirely thrown away, 

 that the difficulty rather was how to keep it under, than to 

 economise it. The converter, however, and the regenerative gas 

 furnace had materially changed that condition of things. The 

 heat was now in a great measure utilized to do its work ; it was 

 employed for producing the effect required, and there was little 

 heat to be thrown away. If, therefore, steam was required to 

 work the metal after it was produced, that steam had to be 

 raised by means of special fires, and it became as important to 

 work mill-machinery upon economical principles as it was a 

 steam-engine on board ship. No wonder, then, that economical 

 engines had attracted the attention of those practically engaged 

 in working steel ; and he quite agreed with the author in 

 selecting a compound engine as the type which was perhaps 

 the most suitable for the purpose. It distributed the load very 

 uniformly upon the crank centre, and it carried out the system 

 of expansion without involving a maximum strain too much above 

 the mean strain on the working piston. The author proceeded to 



