WHAT WE OWE TO THE SUN. 45 



every source of light may ultimately be traced back to 

 sunbeams in one form or another. 



Let us take as a splendid example the electric light, 

 which as ordinarily produced is ultimately due to sun- 

 beams. No doubt it is immediately derived from a pair of 

 carbon points, but the current necessary for the purpose is 

 obtained from a dynamo, which must be driven by some 

 source of power, usually a steam-engine. It follows that 

 the power of the steam-engine is the source of the electric 

 light ; but the steam-engine is driven by steam, and the 

 steam is made from water, and the water is heated by 

 coal : thus it is coal which actually generates the electric 

 light the boiler, the water, the steam-engine, the dynamo, 

 the wires, and the carbon points are merely appliances by 

 which something which has been stored in the coal is 

 applied to the particular purpose of generating light. 

 The coal, as we have seen, has derived its potency from 

 the sunbeams which shone on the ancient forests at the 

 time of the formation of the coal measures. Our electric 

 lights to-night may be regarded as a resuscitation on a 

 feeble scale of sunbeams emitted from the orb of day 

 millions of years ago. 



In such a case as that just considered, we seem to be 

 drawing on an accumulated hoard of sunbeams stored 

 away in the earth's interior ; but we can also utilise what 

 we may describe as the present radiation of the sun from 

 day to day for the production of artificial illumination. 

 For the prodigious energy of modern civilisation the Falls 

 of Niagara have to be rendered serviceable, even though 

 the process involves a lamentable sacrifice of their beauty. 

 The power of those Falls suitably applied to water-wheels 



