NATURAL PHILOSOPHY. 145 



Let us now compare this heat with the amount of the same agent 

 generated by the fall of an asteroid into the sun. Without taking 

 into account the low specific heat of such masses when compared with 

 that of water, we find the heat developed by the asteroid to be from 

 7,000 to 11, 000 times greater than that of the oxyhydrogcn mixture. 

 From data like these the extraordinary diathermic energy of the sun's 

 ravs, the immense radiation from his surface, and the high tempera- 

 ture in the focus of the ivlle -tor are easily accounted for. 



The facts above mentioned show that unless we assume on the sun 

 the existence of matter with unheard-of chemical properties as a dcus 

 ex mnc.'tind, no chemical process could maintain the present high radi- 

 ation of the sun ; it also follows from the above results that the chem- 

 ical nature of bodies which fall into the sun does not in the least aifect 

 our conclusions ; the effect produced by the most inflammable sub- 

 stance would not differ by yoVo" part from that resulting from the fall 

 of matter possessing but feeble chemical affinities. As the brightest 

 artificial light appears dark in comparison with the sun's light, so the 

 mechanical processes of the heavens throw into the shade the most 

 powerful chemical actions. 



The quality of the sun's rays, as dependent on his temperature, is 

 of the greatest importance to mankind. If the solar heat were orig- 

 inated by a chemical process, and amounted near its source to a tem- 

 perature of a few thousand degrees, it would be possible for the light 

 to reach us, whilst the greater part of the more important calorific 

 rays would be absorbed by the higher strata of our atmosphere and 

 then returned to the universe. 



In consequence of the high temperature of the sun, however, our 

 atmosphere is highly diathermic to his rays, so that the latter reach 

 the surface of our earth and warm it. The comparatively low tem- 



by the solar rays, but which offers considerable resistance to the radi- 

 ant heat escaping from our earth ; its action resembles that of a valve 

 which allows a liquid to pass freely in one direction, but stops the 

 ilow in the opposite. 



The action of the atmosphere is of the greatest importance as 

 regards climate and meteorological processes. It must raise the mean 

 temperature of the earth's surface. After the setting of the sun, in 

 fact, in all places where his rays do not reach the surface, the tem- 

 perature of the earth would soon be as low as that of the universe if 

 the atmosphere were removed, or if it did not exist. Even the 

 powerful solar rays in the tropics would be unable to preserve water 

 in its liquid state. 



Between the great cold which would reign at all times and in all 

 places, and the moderate warmth which in reality exists on our globe, 

 intermediate temperatures may be imagined ; and it is easily seen that 

 the mean temperature would decrease if the atmosphere were to 

 become more and more raiv. SiK'li a rarefaction of a valve-like act- 

 ing atmosphere actually takes place as we ascend higher and higher 

 above the level of the sea, and it is accordingly and necessarily 

 accompanied by a corresponding diminution of temperature. 

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