PRODUCTION OF MECHANICAL EFFECT. 441 



the sailing ships of other nations, which must be 

 reckoned in the account, and throw in the little 

 item of windmills, we find that, even in the present 

 days of steam ascendency, old-fashioned Wind 

 still supplies a large part of all the energy used by 

 man. But however much we may regret the time 

 when Hood's young lady, visiting the fens of Lin- 

 colnshire at Christmas, and writing to her dearest 

 friend in London (both sixty years old now if 

 they are alive), describes the delight of sitting in 

 a bower and looking over the wintry plain, not 

 desolate, because " windmills lend revolving anima- 

 tion to the scene," we cannot shut our eyes to the 

 fact of a lamentable decadence of wind-power. Is 

 this decadence permanent, or may we hope that it 

 is only temporary ? The subterranean coal-stores 

 of the world are becoming exhausted surely, and 

 not slowly, and the price of coal is upward bound 

 upward bound on the whole, though no doubt it 

 will have its ups and downs in the future as it has 

 had in the past, and as must be the case in respect 

 to every marketable commodity. When the coal 

 is all burned ; or, long before it is all burned, when 



