RECENT PROGRESS IN RELATION TO THE THEORY OF HEAT. 243 



M. Poiiillet, we fiud that the sun disengages in a year a qnantit_y of heat capable 

 of melting a covering of ice 1,500 leagues in thicknes^i, whi(;h might envelop 

 a globe one million four hundreil thousand times larger than the earth. 



IIou" arc we to explain this enormous production of heat? Is it the result of 

 a combustion analogous to those which take place on our hearths ? To be con- 

 vinced of the impossibility c»f such an origin, it suffices to know that if the sun 

 were a globe of cliarct)al burning in oxygen, it would be consumed in 5,000 

 years. 



The new theory of heat has led to an hypothesis which satisfies the mind up 

 to a certain point. The universe is filled with bodies called asteroids, which 

 gravitate under the control of imdiscovered laws. It is they which produce the 

 shooting stai's and meteorites. Now, it is easily conceivable that such bodies may 

 fall regularly upon the sun and create heat by the impact. It has been calcu- 

 lated what would be the mass of asteroids capable of thus producing the solar 

 heat, and it has been found that it would form in a year a simple stratum of 20 

 metres (21.872 yards) at the surface of the sun. It would, at this rate, require 

 more than a million five hundred thousand centiu'ies for the diameter of the solar 

 disk to appear doubled. Our instruments of astronomy are not sufficiently sensi- 

 tive to enable us to observe an augmentation so slow ; thus the hypothesis does 

 not stand in opposition to facts. \Vo should not forget, however, that all this is 

 conjecture, nor can we plume ourselves on having discovered the cause of the 

 phenomena which have been observed. 



After the solar heat, it remains to speak of the terrestrial heat, of which we 

 have striking manifestations in volcanic eruptions, in the geysers, tliose gigantic 

 eruptions of boiling water which are met with in Iceland, to say nothing of the 

 tranquil indications of artesian wells. The laws of these phenomena are not in 

 general completely known, though that of the geysers has been artificially repro- 

 duced upon the ingenious theory of Bunsen. What shall it be said is the origin 

 of this terrestrial heat ? Everything would lead us to believe that the earth was 

 primitively an incandescent fluid nuiss, and thus its condition would be analogous 

 to that of the sun. An incessant fall of cosmical matter would maintain its heat 

 .and gradually enlarge its nmss. Some time or other this sup{)ly has failed, and 

 the globe, in cooling, undergone solidification at the surface. Then only did it 

 become the earth. 



Thus it will be seen that the generation of heat by the destruction of move- 

 ment will serve to explain the production of heat in chemical combinations, in 

 the Voltaic circuit, in the organs of living beings — nay, it will furnish no improb- 

 able hypothesis of the origin of solar and terrestrial heat. Art; we not tempted 

 hence to conclude that heat is likewise a movement? We thereby associate the 

 connection we have observed with a great and more general principle than the 

 preceding, that of the conservation of energy. In virtue of this principle, if * 

 movement ceases in one body, it commences in a neighboring l)ody, so that noth- 

 ing is lost ; all the phenomena of the material world result from an exchange of 

 movement between bodies, one gaining what the oiher loses.* There is nothing 

 which seems to oppose itself to tliis generalizaticm ; it oilers us a picture of what 

 we learn by the senses, and by accepting it as a law, we yield to the sentiment 

 of unity which the Creator has implanted in our souls. But we should be cir- 

 ciunspect ; we niust ntjt allow 'ourselves to be swayed by imagination, nor sur- 

 render reason to the seductive creations of our own invention. 



The generation of heat may be a transtbrmation ()f movement, but what is the 

 intermediary of that transformation ? In order to raise the veil which conceals 

 from us the mystery of creation, is it sufficient to say that matter transmits 



* The .statement verjuire.s limit.'ilioii. It cannot Ik; said tlic.t tlie motion ov onertfy of a 

 cannon ball i.s all transfV'ircil to the .side of" the .ship which it pciu'tratcs — a larpe part is 

 expended iu niakiufj the hole, another portion in producing the noise of the percussion, and 

 the remainder in generating heat. — J, H. 



