136 THE SCIENTIFIC PAPERS OF 



In the discussion of the Paper 



"ON THE WARSOP AERO-STEAM ENGINE," 

 By Mr. RICHARD EATON, 



THE CHAIRMAN (MR. C. WILLIAM SIEMENS) * remarked that 

 the subject of the paper was a very interesting one, both on 

 account of the theoretical questions involved, and also in conse- 

 quence of the practical results that had been arrived at, which 

 seemed to be of a decidedly favourable character. 



The main question that presented itself in regard to the use 

 of the air injection was, what was the cause of the advantages 

 ascribed to it. These advantages were of two kinds : first, the 

 advantage in the boiler of preventing sediment and preventing 

 priming by the injection of heated air into the water ; and secondly 

 the advantage in the engine of getting more work done by a given 

 volume of the mixed steam and air than would be performed by an 

 equal volume of steam alone at the same pressure. 



With regard to the advantage in the boiler, consequent upon the 

 injection of divided currents of heated air into the water, he thought 

 there was reason to, anticipate a marked effect from such a process ; 

 for each bubble of heated air rising through the mass of hot water 

 would naturally become saturated with steam by its contact with 

 the water, increasing in volume many times, and would thus relieve 

 the evaporating surface of the boiler of part of the work it woukj 

 otherwise have to perform. Moreover in ordinary boilers, the steam 

 being generated only in contact with the evaporating surfaces of 

 the boiler-plates and tubes, each bubble of steam at the moment of 

 its generation left behind it a liberated particle of solid matter, 

 which had previously been contained in the water ; and this being 

 liberated in immediate contact with the boiler surface, it was natural 

 and probable that it should attach itself at once to that surface in 

 the form of a solid incrustation. If however the required evapora- 

 tion in a boiler could be produced otherwise than in contact with the 



* Excerpt Minutes of Proceedings of the Institution of Mechanical Engineers, 

 1870, pp. 245-248. 



