6 president's address. 



and his partners to devote all their energy to extend the adoption of 

 the engine as it stood, and this they did, and to the Watt engine, 

 consuming from five to seven pounds of coal per horse-power, mankind 

 owes the greatest permanent advances in material welfare recorded in 

 history. 



With secondary modifications, it was the prime mover in most 

 general use for eighty years — i.e., till the middle of last century. It 

 remained for others to carry the expansion of steam still further in 

 the compound, triple, and, lastly, in the quadnaple expansion engine, 

 which is the most economical reciprocating engine of to-day. 



Watt had considered the practicability of the turbine. He writes 

 to his partner, Boulton, in 1784: ' The whole success of the machine 

 depends on the possibility of prodigious velocities. In short, without 

 God makes it possible for things to move them one thousand feet per 

 second, it cannot do us much harm.' The advance in tools of pre- 

 cision, and a clearer knowledge of the dynamics of rotating bodies, 

 have now made the speeds mentioned by Watt feasible, and indeed 

 common, everyday practice. 



Turbines. — The turbine of to-day carries the expansion of steam 

 much further than has been found possible in any reciprocating engine, 

 and owing to this property it has surpassed it in economy of coal, 

 and it realises to the fullest extent Watt's ideal of the expansion of steam 

 from the boiler to the lowest vapour pressure obtainable in the condenser. 



Among the minor improvements which in recent years have con- 

 duced to a liigher efficiency in turbines are the more accurate curvature 

 of the blades to avoid eddy losses in the steam, the raising of the 

 peripheral velocities of the blades to nearly the velocity of the steam 

 impinging upon them, and details of construction to reduce leakages 

 to a minimum. In turbines of 20,000 to 30,000 horse-power 82 per 

 cent, of the available energy in the steam is now obtainable as brake 

 horse-power; and with a boiler efficiency of 85 per cent, the thermo- 

 dynamic efficiency from the fuel to the electrical output of the alter- 

 nator has reached 23 per cent., and shortly may reach 28 per cent., 

 a result rivalling the efficiency of internal combustion engines worked 

 by producer gas. 



During the twenty years immediately preceding the war turbo- 

 generators had increased in size from 500 kilowatts to 25,000 kilowatts, 

 and the consumption of steam had fallen from 17 lb. per kw. hour 

 to 10.3 lb. per kw. hour. Turbines have become the recognised means 

 of generating electricity from steam on a large scale, although they 

 have not superseded the Watt engine for pumping mines or the drawing 

 of coal, except as a means for generating electricity for these purposes. 

 In the same period the engine power in the mercantile marine had risen 

 from 3,900 of the King Edward to 75,000 of the Mauretania. 



