196 ON THE INTERACTION OF NATURAL FORCES. 



From the same formula we can deduce that a dimimition 

 of ^1^ of the radius of the sun would generate work in a 

 water mass equal to the sun, equivalent to 2,861 degrees 

 Centigrade. And as, according to Pouillet, a quantity of 

 heat corresponding to 1 J degree is lost annually in such a 

 mass, the condensation referred to would cover the loss for 

 2,289 years. 



If the sun, as seems probable, be not everywhere of the 

 same density, but is denser at the centre than near the 

 surface, the potential of its mass and the corresponding 

 quantity of heat will be still greater. 



Of the now remaining mechanical forces, the vu viva of 

 the rotation of the heavenly bodies round their own axes 

 is, in comparison with the other quantities, very small, 

 and may be neglected. The ins viva of the motion of 

 revolution round the sun, if /j, be the mass of a planet, 

 and p its distance from the sun, is 



L = 



grmfifl 



\R 2p 



h\- 



Omitting the quantity -- as very small compared with -— , 

 2p -tv 



and dividing by the above value of V, we obtain 



L 5 ^ 

 V^ M* 



The mass of all the planets together is ,— — of the mass 



738 



of the Sim ; hence the value of L for the entire system is 



