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foiined from trees and plants, which were produced at the expense 

 of some of the energy of the sun, and when the coal is burned, the 

 energy originally absorbed by the plant re-appears as heat. The 

 process by which the heat, produced by the combustion of coal, is 

 applied to the performance of work in the steam engine, was then 

 described, and it was stated that in the best steam engines at 

 present not less than 90 per cent, of the energy due to the coal 

 escapes unutilised, only 10 per cent, being applied to do work. It 

 was explained that it is impossible by any improvement of the steam 

 engine to do more than recover a small portion of the 90 per cent. 

 now wasted, the amount utilised being perhaps increased to 20 per 

 cent., and there being many difficulties in the way of accomplishing 

 even this. In conclusion, it was pointed out that the stock of 

 available coal in Great Britain is being drawn upon at a rapidly 

 increasing rate, and that, at no very distant time, the increased 

 prices must seriously affect the manufacturing industries of the 

 country. The possibility of making more use of the energy of 

 streams and tides was then alluded to. Several models and diagrams 

 were exhibited in illustration of the lecture. 



