.S7A 1 W U.LI AM .S7AM//.-.Y.S-, l-.R.S. 93 



and the total amount of available water-power in such districts is 

 extremely limited. 



Wind Power. Another result of solar energy are the winds, 

 \vluVh have been utilised for the production of power. This 

 source of power is, indeed, very great in the aggregate, but its 

 application is attended with very great inconvenience. It is 

 proverbial that there is nothing more uncertain than the wind, 

 and when we were dependent upon windmills for the production 

 of flour, it often happened that whole districts were without that 

 necessary element to our daily existence. Ships also, relying upon 

 the wind for their propulsion through the sea, are often becalmed 

 for weeks, and so gradually give place to steam-power on account 

 of its greater certainty. 



Heat ly Radiation. It has been suggested of late years to utilise 

 the heat of the sun by the accumulation of its rays into a focus by 

 means of gigantic lenses, and to establish steam-boilers in such 

 foci. This would be a most direct utilisation of solar energy, but 

 it is a plan which would hardly recommend itself in this country, 

 where the sun is but rarely seen, and which even in a country like 

 Spain would hardly be productive of useful, practical results. 



Tidal Power. There is one more natural source of energy 

 available for our uses, which is rather cosmical than solar viz., 

 the tidal wave. This might also be utilised to a very considerable 

 extent in an island country, facing the Atlantic ocean, like this, 

 but its utilisation on a large scale is connected with great practical 

 difficulty and expenditure, on account of the enormous area of 

 tidal basin that would have to be constructed. 



In passing in review these various sources of energy which are 

 still available to us, after we have run through our accumulated 

 capital of potential energy in the shape of coal, it will have struck 

 you that none of them would at all supply the place of our 

 willing and ever-ready slave the steam engine ; nor would they 

 be applicable to our purposes of locomotion, although means might 

 possibly be invented of storing and carrying potential energy in 

 other forms. But it is not force alone that we require, but heat 

 for smelting our iron and other metals, and the accomplishment 

 of other chemical processes. We also need a large supply for our 

 domestic purposes. It is true that with an abundant supply of 

 mechanical force we could manufacture heat, and thus actually 



