BY P. L. WESTON, B.SC, B.E. VII. 



the onward march of civilisation is marked by an ever 

 insistent demand for power. The immense progress of 

 the past centnry is largely to be attribnted to the de- 

 velopment of the steam engine, which has reigned su- 

 preme as a prime mover or machine for the i:)roduction 

 of mechanical power since the days of Watt. There are 

 many signs, however, that this supremacy is being seri- 

 ously challenged by the internal combustion engine, 

 mainly by reason of its superior efficiency as a heat en- 

 -gine or apparatus for turning the energy of fuel into 

 mechanical power. We know from a study of the theory 

 of heat engines that of the total energy to be derived 

 from the combustion of fuel not more than about 15 

 per cent, can be converted into mechanical work by the 

 combination of a steam boiler and steam engine or tur- 

 bine, whereas with an internal combustion engine as 

 much as 35 per cent, of the fuel energy can be converted 

 into useful work. Hence it is safe to assume that the 

 promise of the future lies with the engine having the 

 higher intrinsic efficiency, and in the same way as the 

 19th century can be aptly called the steam age so the 

 ^Oth century seems destined to merit the designation of 

 the gas age. The term gas engine can for the sake of 

 brevity be used to include all forms of internal combus- 

 tion engines. 



Except in a few favoured localities where water 

 power is available power has to be mainly de- 

 rived from the combustion of fuel of various 

 kinds, of which coal is the chief. Consequently 

 one of the most important of a nation's assets 

 lies in its stores of fuel and the rate of consumption is 

 so rapid that the question of the conservation of fuel 

 resources is one of ever increasing urgency. From time 

 to time we have pointed out the inevitability of the early 

 depletion of our coal and other natural fuels, especially 

 of the higher grades, but unfortunately too little heed is 

 paid to this matter of vital national importance. Fortun- 

 ately much of the present waste of fuel can be minimised 

 by the adoption of the internal combustion engine, with its 

 superior economy and adaptability to use low grade fuels, 

 which are at present discarded. Tli? economic import- 



